US20150233230A1

US20150233230A1 - Borehole inspecting and testing device and method of using the same

Info

Publication number: US20150233230A1
Application number: US14/560,879
Authority: US
Inventors: Garland E. Likins, Jr.; George R. Piscsalko; Frank Frank Rausche; Dean A. Cotton
Original assignee: Pile Dynamics Inc
Current assignee: Pile Dynamics Inc
Priority date: 2013-12-05
Filing date: 2014-12-04
Publication date: 2015-08-20

Abstract

A borehole inspection device and method of using the same to measure the condition of the bottom extent of a borehole, the system having a head unit assembly with top and bottom sides and including at least one downwardly extending force sensor configured to measure a reaction force applied to the at least one sensor as it engages a bottom extent of the borehole, the inspection device being configured to be lowered into a borehole and to bring the sensor(s) into contact with the bottom extent wherein continued downward movement of the head unit creates the reaction force on the sensor(s) to determine at least one of a location of an associated debris layer, a bearing capacity of the associated debris layer, the thickness of the associated debris layer, the location of an associated bearing layer and/or the bearing capacity of the associated bearing layer.

Description

This application claims priority in provisional patent applications Ser. No. 61/912,206 that was filed on Dec. 5, 2013, which is incorporated by reference herein.
The invention of this application relates to a borehole measuring device. More particularly, the invention of this application relates to a measuring device that can be deployed in a borehole to inspect the borehole, in particular, to inspect the shaft bottom and/or side walls of the borehole and provide fast and reliable information about the quality and bearing capacity of the soils in the borehole.

INCORPORATION BY REFERENCE

McVay et al.—U.S. Pat. No. 6,533,502 discloses a wireless apparatus and method for analysis of piles which is incorporated by reference herein for showing the same. In addition, Mullins et al.—U.S. Pat. No. 6,783,273 discloses a method for testing integrity of concrete shafts which is also incorporated by reference in this application for showing the same. Piscsalko et al.—U.S. Pat. No. 6,301,551 discloses a remote pile driving analyzer and is incorporated by reference in this application for showing the same. Likins Jr. et al.—U.S. Pat. No. 5,978,749 discloses a pile installation recording system and is incorporated by reference in this application for showing the same. Piscsalko et al.—U.S. Pat. No. 8,382,369 discloses a pile sensing device and method of using the same and is incorporated by reference in this application for showing the same. Dalton et al.—Publ. No. 2012/0203462 discloses a pile installation and monitoring system and method of using the same and is incorporated by reference in this application for showing the same.
Ding—U.S. Pat. No. 8,151,658 discloses an inspection device for the inspection of an interior bottom of a borehole which is incorporated by reference herein for showing the same. Tawfiq et al. U.S. Pat. No. 7,187,784 discloses a borescope for drilled shaft inspection and is incorporated by reference herein for showing the same. In addition, Tawfiq et al. U.S. Pat. No. 8,169,477 discloses a digital video borescope for drilled shaft inspection and is incorporated by reference herein for showing the same.

BACKGROUND OF THE INVENTION

Applicant has found that the invention of this application works particularly well with the drilling and inspection of drilled pile shafts wherein this reference is being used throughout this application. However, this application is not to be limited to drilled pile shafts wherein reference to piles in this application is not to limit the scope of this application. “Piles” can equally refer to drilled shafts or other deep foundation elements. Application to shallow foundations is also useful.
Sensing apparatuses have been used in the building and construction industry for a number of years. These sensing apparatuses include a wide range of devices used for a wide range of reasons in the field. These devices include sensing devices that are used in connection with the installation and use of supporting elements such as piles that are used to support the weight of superstructures such as but not limited to supporting the weight of buildings and bridges. As can be appreciated, it is important to both ensure that a supporting foundation element, such as a pile, has been properly formed and installed and that structurally it is in proper condition throughout its use in the field. It must also have sufficient geotechnical bearing capacity to support the applied load without excessive settlement.
With respect to the installation of piles, it is important that these structures be properly constructed so that the pile can support the weight of a building or superstructure. Thus, over the years, systems have been designed to work in connection with the installation of a pile to ensure that this pile meets the building requirements for the structure. These include sensing devices that work in connection with the driving of a pile as is shown in Piscsalko et al., U.S. Pat. No. 6,301,551. Again, the Piscsalko patent is incorporated by reference herein as background material relating to the sensing and driving of structural piles. These devices help the workers driving these piles to determine that the pile has been properly driven within the soil without over stressing the pile during the driving process, and assure the supervising engineer that the pile meets all design requirements including adequate geotechnical bearing capacity.
Similarly, devices are known which are used to monitor the pile after it is driven. This includes the Piscsalko patents which include devices that can be used to monitor the pile even after the driving process. Further, Mcvay, et al., U.S. Pat. No. 6,533,502 also discloses a device used to monitor a pile during or after the driving process is completed. The information produced by the systems can be used to determine the current state of the pile, including the geotechnical bearing capacity, and for determining a defect and/or damage, such as structural damage, that may or may not have incurred in response to any one of a number of events including natural disasters.
In addition, it is known in the art that devices can be used to help determine the structural integrity of a poured pile wherein the pouring of the pile and the quality of this pouring can determine the structural integrity of the pile once a poured material like concrete has cured. Mullins, et al., U.S. Pat. No. 6,783,273 attempts to measure this integrity of a poured pile by disclosing a system and method for testing the integrity of concrete shafts by moving a single thermal sensor arrangement up and down in a logging tube during the curing cycle of the concrete in the poured pile. Piscsalko U.S. Pat. No. 8,382,369 discloses an alternative to the Mullins device and discloses a thermal pile sensing device that includes one or more sensor strings, each with multiple thermal sensors, that are capable of monitoring the entire pile generally simultaneously and over a period of time and can create two or three dimensional images, in real time, based on the curing of the poured material to assess structural integrity and/or other structural characteristics.
However, while the prior art disclosed above can effectively measure the integrity of the pile and certain aspects of the borehole during or after the pouring of the pile, the bearing capacity of the pile is also and more usually dependent on the condition of the soil around the length of the shaft and below the bottom borehole before the pile is poured. The bearing capacity at the bottom of the borehole relates to condition of the soil at the bottom of the borehole wherein loose soil has less bearing capacity than soils that are undisturbed or dense. Loose soil also contributes to undesirable increased settlement of the supported structure. Thus, it is best to reduce the amount of loose soil at the bottom of the borehole. In view of the difficulties associated with viewing the bottom of a borehole that can be many meters below the ground surface, and frequently in an opaque slurry condition consisting of suspended clay particles mixed in water, or possibly a liquid polymer mixture, it is common practice to employ a so-called “clean-out bucket” to reduce the amount of unsuitable bearing material, such as loose soil, at the shaft bottom. This procedure requires replacing the drilling equipment with the clean-out bucket which is then lowered into the borehole. The success of the bottom cleaning is, however, not assured and several passes or cycles of this effort may be needed. The uncertainty can lead to unnecessary effort and, therefore, cost. Throughout the remaining specification of this application, the terminology “debris layer” and/or “debris” will be used to generally define the unsuitable bearing material above the bearing layer. The unsuitable bearing material includes, but is not limited to, loose soil, loose material, soft material and/or general debris. The debris together forms the debris layer.
The devices disclosed in the Tawfiq patents and the Ding patent attempt to overcome these problems by making it possible to inspect the bottom of the borehole and reduce the number of cycles and therefore the time needed for secondary operations, and/or reduce the required additional capacity above the design load to the minimal sufficient margin. Or, at least to confirm that the secondary cleaning operations were successful. Another such device is the Drilled Shaft Inspection Device (SID) produced by GPE, Inc. More particularly, these systems are configured to only visually inspect the borehole before the pile is poured. None of these systems can be used to estimate the capacity of the bearing layer or assure a satisfactory soil condition at the bottom of the borehole. With respect to the Tawfiq systems, they are complicated and heavy systems that are costly to operate in the field. One such problem is that the weight of Tawfiq's system requires the use of large cranes or pulley systems to lower the Tawfiq's system into the borehole, and further to move and assess multiple locations on the bottom surface. Ding attempts to overcome the heavy system shortcomings in Tawfiq by the use of a simple system that is lighter and purely mechanical in design. In this respect, Ding's system is essentially like a hand tool that must be operated by specially trained operators and operated at or near the borehole by these operators wherein the operator must cautiously work near an open borehole. In operation, these operators must manually and carefully lower the Ding system into a borehole without bumping the side wall since any movement of the bottom plate before it reaches the bottom of the borehole could require the system to be retrieved to the surface and reset. In this respect, Ding utilizes manual plate movements to measure the depth of the debris layer at the bottom of the borehole, and retrieving the device after each measurement to record the result prior to deploying the device again to measure the next bottom location. While Ding overcomes some of the complexity, weight and costs associated with the Tawfiq systems, the Ding system is significantly more labor intensive since each measurement requires the system to be completely removed from the borehole and the displacement of the bottom plate visually determined and manually reset. For larger boreholes, this can be numerous iterations to sufficiently measure the entire bottom of the borehole wherein each iteration requires the device to be completely removed from the hole. For deep shafts, the time to retrieve and redeploy is substantial. Yet further, the Ding system is designed only to measure the height of debris layer at the bottom of the borehole; it is not capable or configured for other measurements. In fact, it is too light and thus incapable of measuring load bearing characteristics of the soil in the bearing layer. While for other reasons, the other systems discussed above are also not capable of measuring load bearing characteristics. As a result, Ding's attempts to simplify his system over the prior art ultimately resulted in greatly increased labor cost to operate his system. In addition, Ding's simplified system also results in a reduced amount of data that can be obtained since his system can only measure the amount of debris. Yet further, Ding's simplified system necessitates highly skilled operators to operate his system and to operate the system near the open borehole. Thus, while Ding overcomes some of the complexity issues relating to the prior art, it creates new and different problems in the art. Most importantly, however, both the Tawfiq and the Ding devices require skilled personnel, not necessarily skilled in safe construction work practices, to approach and work next to a large borehole, either filled with slurry or empty. This is generally not advisable, and in some instances, not permitted on a construction site. Additionally, these systems only attempt to measure the debris layer on the bottom of the borehole, but none of the prior art can give any indication of the capacity of the soil of the bearing layer, or of the condition of the sidewall.
Therefore, there is still a need for a system to inspect and test a borehole's soil strength before a pile is poured that reduces the complexity and cost of the system without adversely increasing labor costs by requiring highly skilled operators at the jobsite for long periods of time and working near the borehole. Yet further, there is a need for a system that makes it less costly to inspect and test the borehole bottom and/or sides and reduces the need for, or time required by, the secondary excavating system to clean up the debris on the bottom of the borehole.

SUMMARY OF THE INVENTION

The invention of this application relates to a borehole inspection device; and more particularly, to a borehole or shaft hole inspection device and system.
More particularly, the invention of this application relates to a borehole inspection that can quickly and accurately measure the debris layer in a borehole.
According to one aspect of the present invention, provided is a device which produces load-set curves or load versus displacement curves for one or more locations of the shaft bottom and/or sides to give the construction professional quick and reliable information about the quality and bearing capacity of the soils underneath the shaft bottom and/or the condition of the side walls of the shaft. Due to uncertainty in the bottom of shaft condition, a designer often ignores end bearing and relies only on resistance along the side of the shaft when assessing the bearing capacity of the shaft. By using the device of this application, designers can with more confidence include end bearing in their design and thus potentially save significant amounts of money in the overall cost of the pile. This is particularly important when the shaft has to carry end bearing.
More particularly, in one set of embodiments, the device can measure soil resistance by utilizing a reaction load and this reaction load can be a substantial reaction load produced by the weight of the already present and massive drilling equipment.
According to yet another aspect of the invention of this application, this device can measure a reaction load to both determine the depth of the debris layer on the surface of the bottom of the borehole bottom and measure the load capacity of the bearing layer of the borehole below the debris layer.
According to a further aspect of the invention of this application, the device can measure one or more conditions of the side of the borehole wherein the designer can with more confidence design for bearing capacities and thus potentially save more money by justifiably reducing the safety margin (by either decreasing the assumed ultimate bearing capacity or increasing the design load since in either case the actual capacity is then better known).
According to even yet another aspect of the invention of this application, the device can use the weight of the drilling equipment as a reaction load. In fact, the device is conceived in such a way that it allows quick connection to the drilling equipment, which is already present on site to drill the foundation hole, and in that way it eliminates the need for setting up cumbersome additional equipment and reduces to a minimum any time delays between the end of the drilling process and the beginning of concrete casting. Yet further, the device of this application is therefore built such that it can be handled by the contractors' skilled personnel who are trained to be around a borehole and allow the analyzers of the data to supervise the operation and analyze the data without ever going near the borehole, may be as far away as in their office.
According to a further aspect of the invention of this application, the device can include multiple sensors and these multiple sensors can detect and test more than one characteristic of the borehole.
According to another aspect of the invention of this application, this device can be configured to quickly connect to the drilling equipment wherein separate and independent lowering systems are not required thereby eliminating the need for setting up cumbersome additional equipment and reducing to a minimum any time delays between the end of the drilling process and the beginning of concrete casting.
According to yet another aspect of the invention of this application, the device can include both force and displacement sensors thereby measuring both the amount of debris and/or the bearing capacity of the bearing layer of the borehole bottom and/or sides.
According to yet other aspects of the present invention, the device can include the sensing on a device head that is lowered into the borehole and a readout system spaced from the head that can be in communication with the device head (by wired, wireless, and/or underwater wireless systems) that can display real time data viewable by the operator of the device, personnel on site and/or personnel off site thereby preventing the system from being removed from the borehole for each location tested on the borehole bottom, thus improving efficiency and reducing the time required for testing.
According to even yet other aspects of the invention, the testing device can be joined relative to a cleanout bucket thereby creating a combination debris cleaning and layer testing device.
According to yet a further aspect of the invention, provided is a device that can measure and determine at one or more points simultaneously:

The thickness of the debris layer and its strength
The strength of the bearing layer below the debris layer
The elastic modulus of the bearing layer
The uniformity of the debris layer and/or the bearing layer
The strength and/or condition of the sides of the borehole

These and other objects, aspects, features, advantages and developments of the invention will become apparent to those skilled in the art upon a reading of the Detailed Description of the invention set forth below taken together with the drawings which will be described in the next section.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which form a part hereof and wherein:

FIG. 1 is a perspective view a prior art cleanout bucket utilized to clean the bottom surface of a borehole;

FIG. 2 is a side elevational view the prior art cleanout bucket shown in FIG. 1;

FIG. 3 is an elevational view taken at the bottom of a borehole and which shows an embodiment of the invention of this application at a set or initial engagement point;

FIG. 3A is an elevational view taken at the bottom of a borehole and which shows an embodiment of the invention of this application at the bottom of the borehole as sensors begin to engage the bearing layer;

FIG. 3B is an elevational view taken at the bottom of a borehole and which shows an embodiment of the invention of this application at the bottom of the borehole as sensors fully engage the bearing layer;

FIG. 4 is a graph showing displacement and force relationship for a sensor of the device of this application;

FIG. 5 is an elevational view taken at the bottom of a borehole and which shows another embodiment of the invention of this application;

FIG. 6 is an elevational view which shows yet another embodiment of the invention of this application;

FIG. 7 is an elevational view which shows a further embodiment of the invention of this application;

FIG. 8 is an elevational view which shows yet a further embodiment of the invention of this application;

FIG. 9 is a bottom view of a plate that can be used with embodiments of this application;

FIG. 10 is an elevational view of yet another embodiment of this application configured to also measure the side walls before the pile is poured;

FIG. 11 shows an elevational view of yet a further embodiment of this application including a lateral bearing measurement feature to produce a load versus displacement curve for the borehole side wall;

FIG. 12 shows an elevational view, partially sectioned, of yet a further set of embodiments of this application including a borehole inspecting and testing device joined relative to a cleanout bucket shown in a retracted condition;

FIG. 13 shows an elevational view, partially sectioned, of the borehole inspecting and testing device shown in FIG. 12 in a measurement condition; and,

FIG. 14 shows a bottom view of the borehole inspecting and testing device shown in FIG. 12.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting the same, FIGS. 1 and 2 show a prior art clean out bucket CB which includes a mounting arrangement AR configured to selectively secure the bucket to a drilling mast, drillstem or Kelly bar (not shown in these figures). These masts have a square cross-sectional configuration wherein the mounting arrangement can be sized to slide over the mast and includes a locking features LF to secure the bucket relative to the mast. However, any attachment configuration could be used without detracting from the invention of this application. By including a square configuration, the mast can impart a rotational force on the bucket. The bucket further includes one or more side walls BW and a bottom B having a blade and a blade opening (both not shown). In operation the bucket is rotated such that the blade directs debris (which includes the unsuitable bearing material including, but is not limited to, loose soil, loose material, soft material and/or general debris) through the blade opening into the interior of the bucket. The bucket's function is to remove any debris on the bottom of the borehole to provide a clean bearing layer surface in the borehole. If the borehole is substantially larger than the diameter of the bucket, the operator can move the bucket about the borehole bottom to clean all or most of the borehole bottom. Removing the “debris” contributes to increased end bearing and reduced settlement of the supported structure.
With reference to FIG. 3, shown is a borehole inspection and testing device 10 in a borehole BH. Borehole BH has a side wall SW extending between a top opening O in a ground layer G and a bottom extent BE. Bottom extent BE defines the borehole bottom referenced above and includes both a debris layer DL and a bearing layer BL. As can be appreciated, both layers in the bottom extent can be much thicker than shown wherein this drawing is only intended to be a general representation of these layers for the purpose of describing the invention of this application. Yet further, the bearing layer can extend essentially indefinitely into the ground. As discussed more above, due to its loose conditions, the debris layer has much less load bearing capacity and contributes to undesirable excessive settlement of the supported structure, wherein it is desired to minimize this layer and remove or eliminate as much debris as possible. Conversely, the bearing layer has a much greater bearing capacity; however, there are still many factors that impact the bearing capacity of the bearing layer. Accordingly, even though it is known that the bearing capacity of the bearing layer is greater than that of the debris layer, the exact bearing capacity is not known and cannot be determined by prior art systems.
FIG. 3 further shows inspection and testing device 10 in borehole BH. Device 10 includes a downhole testing head unit or head assembly 12 along with one or more surface control and/or display unit(s) 14 that can be in direct communication with testing unit 12 by way of one or more communication lines that will be discussed more below. Yet further, control and/or display unit 14 could be an integral part of the overall device which is lowered into the borehole as part of the entire system, preprogrammed to perform the required testing, and guided by electronic sensors. Testing unit 12 includes a head plate or assembly 16 having a top 20 and a bottom 22. Plate 16 further includes sides 30-33 (33 not shown). However, the configuration shown in these drawings is not intended to limit the invention of this application wherein plate 16 can be a wide range of shapes and sizes; including a device having a cylindrical configuration. In one embodiment, plate 16 is about 18 inches in diameter and would be operated to take several readings around the borehole bottom for larger boreholes.
Extending from top side 20 is a mounting arrangement 40 that is shaped to receive a Kelly bar KB or drillstem. Mounting arrangement 40 includes a locking bar 42 to lock unit 12 relative to the bar KB and maintain the engagement between the bar and the device. Plate or assembly 16 can include one or more holes or openings 46 that can allow unit 12 to more freely descend through standing water in the borehole. However, it must be understood that the invention of this application is not to be limited to the support structures shown and described in this application wherein any type of support structure could be used without detracting from the invention of this application including, but is not limited to, round drill stems, with or without a Kelly bar, and/or dedicated support structures.
Unit 12 can include one or more force sensors, shown in this embodiment are two force sensors 50 and 52 extending out of bottom 22. Force sensors 50 and 52 can include any mechanism or system known in the art or the sensor art to determine an applied load. This can include, but is not limited to, strain sensors or gauges, pressure sensors or gauges, such as gauges 54 and 56, respectively, for sensors 50 and 52. These sensors are configured to measure, force or strain on the sensors that can be used to determine layer depth locations, bearing capacity of the debris layer, the thickness of the debris layer, depth location of the bearing layer and/or the bearing capacity of the bearing layer, which will be disclosed more below. While sensors, such as sensors 50 and 52, are shown and described as “cone sensors,” these sensors can have a wide range of configurations without detracting from the invention of this application including, but not limited to, cone shapes, conical shapes, semi-conical shapes, flat bottomed shapes, spherical bottom shapes and others. In addition, these various shapes can have different cross-sectional sizes and/or configurations including different lengths without detracting from the invention of this application.
Unit 12 can further include one or more displacement sensors, such as the two sensors 60 and 62 shown, which will also be discussed more below. As will be discussed more below, the displacement sensors can work in combination with the force sensors to measure the physical characteristics of the borehole bottom. In this set of embodiments, sensors 60 and 62 are configured to move relative to plate 16 through openings 64-65, respectively. Unit 12 and/or sensors 60 and 62 can include a displacement sensor that can measure the movement of sensors 60 and 62 relative to head unit 12 and/or any other components of the system. Further, sensors 60 and 62 are biased downwardly and can be biased by any mechanical system known in the art. The biasing can include, but is not limited to weights 66, springs (not shown), fluids and the like for the biasing of these sensors downwardly. In order to help prevent sensors 60 and 62 from penetrating the debris layer, these sensors can include bottom plate units 68 and 69, respectively.
In operation, head unit 12 and/or system 10 can be lowered into borehole BH. The unit and/or system can be lowered by way of any system or device known in the art including, but not limited to, the borehole drilling equipment by way of Kelley bar KB and/or a dedicated lifting device, which will be discussed more below. Further, the lowering of the system can be monitored by a depth measuring system 63. Depth measuring system 63 can be any depth measuring system known in the art to measure downward displacement. The system can then be lowered until a reaction force is measured on the one or more of the sensors. This can be displacement of one or more of the displacement sensors and/or a force reading on one or more of the force sensors of the system. The force sensors are configured to relatively easily penetrate through the debris layer, the displacement sensors are configured to rest on top of the debris layer. Thus, the force sensor will penetrate the debris layer and the displacement sensors will not. In one set of embodiments, the displacement of the displacement sensors can be used to measure the depth of the debris layers. Further, the reaction force on the force sensors can be utilized to determine the bearing capacity, or lack thereof, of the debris layer. The downward movement is continued until the force sensors engage the bearing layer. As will be discussed more below, the change in force readings on the force sensors can be used to determine the location of the bearing layer. In this respect, the force reading(s) on the force sensors will change significantly when the force sensors transition into the bearing layer. This, in combination with the displacement sensors, can measure the thickness and/or depth of the debris layer. In accordance with another embodiment, the force sensors alone can measure debris layer depth by monitoring force readings in combination depth measuring system 63.
In one embodiment, the one or more force sensors can be three or more force sensors. The penetration force can be measured in any way including, but not limited to, electronically, hydraulically and/or pneumatically, which includes, but is not limited to, by strain sensors. The hydraulic or pneumatic pressure can be configured to be sensed at the surface which would improve the ruggedness of the device, but could be sensed anywhere along the hydraulic supply lines, including within the borehole at or near plate 16. Semiconductor strain gages can also be used, providing reliable strain measurements even if the strains are small (allowing for large range of load measurements). Calibrated force sensors could also be used and/or one or more sensors having different configurations could be used. For example, one set of force sensors could be configured to measure the lower forces of the debris layer while another set could be configured to measure the larger loads of the bearing layer. For the displacement sensors and/or depth measurement system, the displacement could be measured by any way known in the art including, but not limited to, hydraulically, LVDT, potentiometer, ultrasonic, radar, laser, RF, wirelessly by either sonic waves or laser technology relative to the top of the borehole or otherwise. The displacement could be measured as the distance between the plate 16 and bottom plates 68 and 69. Sensors 60 and 62 also can be weighted and/or spring loaded wherein, in a preferred embodiment, they are lightly weighted with weights 66 so as to keep the bottom plates in contact with the top of the debris of debris layer DL, but allow resistance, but free movement.
All load measurements (from direct force measurements, hydraulic pressure, pneumatic pressure and/or strain measurements converted to force) could be displayed against this displacement measurement, in real time. Ideally one would pair one load transducer display with a nearby displacement measurement, although the average load and average displacement would also provide a meaningful result. Individual measurements would provide information about the variability of the bottom and/or bottom surface angles. However, the measurements could be easily repeated at various locations around the bottom of the sometimes very large shaft diameter. Yet further, other sensors, such as one or more accelerometers or tilt sensors (not shown) could be utilized to measure surface angles.
These sensors, and others, can be in communication with workers on the surface operating the equipment by one or more communication lines between head unit 12 and control unit 14. These communication lines can utilize any technology known in the art and new technology to communicate data to the surface. This can include, but is not limited to, hydraulic lines, electrical lines, data lines, fiber optics, coax cable, USB, HDMI, Ethernet, CAT 5, CAT 5e, CAT 6, serial cables, parallel cables, wireless technology, radio frequency communication, sonar, and/or optical communication. The control system can alternatively be located at or near plate/assembly 16 and operate from within the borehole. As can be appreciated, by utilizing a communication system to transfer data to the surface allows the data to be quickly accessed by the workers and prevents the need to retrieve the system from the borehole after each reading. Yet further, the control unit 14 can be a computing system and can be coupled to one or more other computing systems that can be used, for example, to control the testing operations, track data, store data, analyze data and/or transmit data including transmissions to off-site remote locations. Yet further, the computing system can include one or more local computing systems at the jobsite or borehole, including within the borehole, such as unit 14, and one or more computing systems that are off site (not shown), but in communication with unit 14. Even yet further, a wide range of operating systems can be used by workers and/or engineers and these systems can be any system known in the art including, local systems, network systems, application software, cloud based system and/or a blend of these systems. By using systems, such as a cloud based system, many individuals can monitor and/or evaluate data in real time. As a result, engineers can monitor more than one testing operation and can do so either at the jobsite and/or at a remote location. Further, the operation unit can be separate from the data collection unit. Yet further, this can allow the contractor to operate the system while allowing an engineer to monitor the operation at any desired location. In the embodiment shown in FIG. 3, communication lines 70-73 are used to transfer signals and/or data to unit 14. These lines can be the same lines and/or different lines. For example, one or more lines could be electrical lines to transfer data and other lines could be hydraulic lines to transfer pressure and/or pulses. In the embodiments shown in these figures, line 70 is joined between sensor 50 and control unit 14, line 71 is joined between sensor 60 and control unit 14, line 72 is joined between sensor 52 and control unit 14, and line 73 is joined between sensor 62 and control unit 14. Unit 14 can be any computing system known in the art and can include a data storage and/or a display device, potentially monitored remotely will allow the engineer to make an immediate decision as any necessary cleaning or additional drilling necessary to completing the shaft. Unit 14 can also serve as a data collector to supplement field installation logs and for production documentation.
In operation, the drillstem or Kelly bar KB can be used to lower unit 12 into borehole BH and to direct the device into engagement with bottom extent BE. Further, Kelly bar KB, can be used to provide the application load to unit 12 and/or can be used to determine head depth. As the device approaches bottom BE, sensors 60 and 62 can be used to detect an engagement with debris layer DL, as is shown in FIG. 3. This detection can be used to mark the location or depth of the top surface of the debris layer and, therefore, provide a reference for the measurement of the thickness of any debris. At the same time it can also create a base or reference point for the remaining data readings. As the device is urged further downwardly, as is shown in FIG. 3A, sensors 60 and 62 will remain on top of the debris layer while sensors 50 and 52 will penetrate the debris layer. As a result, in at least one embodiment, sensors 60 and 62 can measure displacement while sensors 50 and 52 measure the force or load applied in any layer on the bottom of the borehole. This can be used to create a displacement and force relationship and/or load versus displacement curves and the basis for the calculation of the soil's elastic modulus. Bottom plates 68 and 69 help maintain sensors 60 and 62 on the top of the debris layer and further downward movement results in sensors 60 and 62 moving relative to head plate 16 wherein this displacement can be measured. Even though force sensors 50 and 52 are moving through the debris layer, they can still measure the resistance, load, force or strain in this movement to generate a load bearing data curve of force versus displacement for this layer. As unit 12 is moved further into the borehole, as is shown in FIG. 3B, sensors 50 and 52 will e engage bearing layer BL as is shown in FIG. 3B. When this occurs, the load applied to sensors 50 and 52 will markedly increase wherein these sensors can be used to determine when these sensors engage the bearing layer and the bearing location or depth of the bearing layer can be calculated or determined. See FIG. 4. In this respect, the load on these sensors will increase in the bearing layer as they encounter denser materials of increased bearing capacity. Thus, when they encounter the bearing layer, the readings of force and/or strain on sensors 50 and 52 will increase. At this point, the displacement of the sensors 60 and 62 between the set point (FIG. 3) (or initial top of debris layer) and the bearing point (FIG. 3B) can be used to determine the thickness and/or depth of the debris layer. Again, as stated above, while only two sets of two sensors are shown in the figures, more or less sensors could be used without detracting from the invention of this application.
In greater detail and with special reference to FIG. 4, as the unit 12 is lowered into the borehole, the force on sensors 50 and 52 is zero and remains zero until unit 12 reaches depth 80 as is shown in FIG. 3. Then, continued downward movement will increase the force on force sensors 50 and 52 wherein sensors 50 and 52 can be used, in some embodiments, to determine the position of debris layer DL and/or bearing layer BL. The forces on sensors 50 and 52 remain low as sensors 50 and 52 move through the debris layer, but could fluctuate based on the debris that is on the bottom of the borehole. Continued downward movement will continue to read lower force levels until 12 reaches depth 82 as is shown in FIG. 3A. At this point, the forces on sensors 50 and 52 will begin to rise rapidly as they engage bottom layer BL in view of the greater density of bearing layer BL. Again, reaching this depth, which can be at least in part recorded by sensors 60 and 62, will cause the sharp increase in forces on sensors 50 and 52 and this sharp increase also could be used to determine the depth and/or thickness of the debris layer along with the location of the bearing layer. However, as is discussed above (and will be discussed more below), separate sensing systems could be used for determining the location of the layers. It should be appreciated that sensors 50 and 52 should be sufficiently long to penetrate into the bearing layer BL prior to the unit 12 bottom reaching the top of the debris layer DL. Then, downward movement of unit 12 can be continued until the forces stabilize, shown as depth 84 in FIG. 3B. When this occurs, the bearing capacity of the bearing layer can be determined. Thus, system 10 can accurately measure the depth location of the top of the debris layer, the thickness of the debris layer, the bearing capacity of the debris layer, the depth location of the top of the bearing layer and the capacity of the bearing layer. In accordance with one set of embodiments, sensors 60 and 62 can be configured to determine both the top extent of the debris layer and the thickness of the debris layer while force sensors 50 and 52 measure the bearing capacity of the debris layer, the bearing capacity of the bearing layer and the top extent of the bearing layer.
Yet further, the measurements can be made at multiple locations around the bottom of the borehole with simple lateral repositioning of unit 12 and without removing unit 12 from the borehole. In addition, these measurements can be analyzed by any operator either at the jobsite or at a remote location. Further yet, this data can be analyzed and stored for operational uses, quality assurance uses and other uses. These movements can be guided by electronic sensors such as gyros, GPS, etc. Additionally, the control system may be part of the mechanical system and operate automatically from within the borehole. This automatic system could include sensors to guide the positioning and movement within the borehole as well as automatically perform the desired test and store all relevant data for later analysis.
With reference to FIGS. 5-14, examples of yet other embodiments are shown. In these figures, like reference numbers are utilized for similar structures in the interest of brevity and system already discussed above are not discussed in reference to these figures in the interest of brevity. These figures are merely intended to show examples are alternative embodiments and can include any feature, function, system, structure and/or component discussed above. Thus, this is not to be interpreted to limit these embodiments.
FIG. 5 shows a head unit 100 that includes a two piece plate design. This design includes a head plate/assembly 112 and secondary plate or assembly 120. In this embodiment, secondary plate 120 can be configured to both determine the location of the debris and bearing layers and also determine capacities. Secondary plate 120 is configured to move relative to plate 112 and this relative movement can be tracked by sensor 60 such it can also be used to measure the location of the debris layer and the depth and/or thickness of the debris layer. In addition, plate 120 can include sensors 130 and 132 to help determine the consistency of the debris layer or confirm the readings of sensors 50, 52 (only one shown in this figure) that can operate as described above.
FIG. 6 shows a head unit 200 that includes a different two piece design. This design includes a head plate/assembly 212 and a secondary plate or assembly 220. In this embodiment, secondary plate 220 is configured to both determine the depth location of the layers and also determine capacities. Yet further, this embodiment, and the other embodiments of this application, can be configured such that the system operates by way of its own weight W. Weight W can be produced by any mechanism including, but not limited to, the weight of the head assembly itself, a secondary weight 222 and/or a secondary spring arrangement 224. Secondary plate 220 can be configured to move relative to plate 212 such that it can operate based on its own weight W and wherein it can also be used to measure the location of the debris layer and the depth and/or thickness of the debris layer. As a result, the system could be lowered by the Kelly Bar or could be lowered by any other means, including but not limited to, a cable connected to a crane, crane-like system or pulley system. In one embodiment, weight W is greater than approximately 50 pounds. In another embodiment, the weight is between approximately 100 and 300 pounds. In a preferred format weight W is approximately 150 pounds. However, it should be noted that while these weights (and ranges of weights) may be preferred, the invention of this application is not limited to these weights and/or ranges. Thus, when the probes penetrate, and in view of the known weight W, this data can be used to determine bearing capacity, or at least to determine the depth and/or thickness of the debris layer. In addition, plate 220 includes one or more sensors 230 and 232 to determine both the consistency of the debris layer and the bearing capacities as discussed above in greater detail in view of the know weight W. The movement of secondary plate 220 relative to primary plate 212 can be tracked for layer location and/or thickness. In addition, further downward movement of the unit forces the plates 212 and 220 together (not shown) to allow additional readings, such as the use of sensors 230 and 232 to determine the bearing capacity of the bearing layer.
FIG. 7 shows a head unit 300 that includes a single plate design. This design includes a head plate/assembly 312 that includes one or more sensors 50, 52 that can operate as described above. However, in this embodiment, location and/or depth can be determined by one or more electronic sensors in sensor unit 320. Sensor unit 320 can work in connection with other systems described in this invention (including, but not limited to sensors 60/62) and can be used to help determine the location of the bottom of the borehole. Sensor unit 320 can be any sensor capable of detecting an object, surface or plane including, but not limited to sonar, radar, lasers and/or optical technologies. Yet further, these sensors alone, or along with others could be utilized to determine if the borehole is vertical. Even yet further, depth could be measured using a sensor detecting the pressure of the fluid, and small changes of fluid pressure then converted to relative displacements. Yet even further, sensor unit 320 could include multiple sensors to help account for differences in fluid densities at different depths for boreholes that are filled with a borehole fluid to help maintain the integrity of the borehole between drilling and filling.
FIG. 8 shows a head unit 400 that is being used to illustrate that the probes or sensors can include different configurations. In this respect, unit 400 includes a head plate 412 with both probes 50, 52 described in greater detail above and one or more flat bottomed probe(s) 420. This embodiment can include other sensor configuration described in this application and can further improve the measuring accuracies of the device. More particularly, one or more sensors of this application can be configured for a single function wherein multiple sensors are used for all needed functions. In this embodiment, probes 420 can be configured to only determine the bearing capacities of the layers in that the flat bottom will reduce penetration and can make it easier to calculate bearing forces. Unit 400 can further include one or more displacement sensors, such as sensors 60 and 62, described above in greater detail.
With reference to FIG. 9, shown is a displacement plate 460 that can be used to replace bottom plate units 68 and 69 of sensors 60 and 62, respectively of any embodiment of this application. Replacing plate units 68 and 69 with one or more movement plates 460 can increase the surface area for the base of the displacement sensors to help prevent the penetration of sensors into the debris layer. This can provide for more accurate depth measurement, or at least can be used to average the depth measurement of the thickness of the debris layer. In that plate 460 moves with the depth sensors, the plate can include openings 470 and 472 to allow sensors 50 and 52 to pass therethrough so that plate 460 can move relative to sensors 50 and 52. Plate 460, along with plate units 68/69 described above, can include one or more holes or openings 480 of any size to help lower the plate and the overall unit into standing water and/or borehole fluids in the borehole. Plate 460 can include one or more attachment arrangements 482 to secure plate 460 relative to the displacement sensors, such as displacement sensors 60 and 62. However, while two attachment locations are shown, this is not required.
With reference to FIGS. 10 and 11, the devices and systems of this application can further include a wide range of other sensors. These other sensor(s) can be configured to measure the layers discussed above and/or other characteristics of the borehole. As is shown in FIG. 10, a borehole measuring device 500 can include a plate unit assembly 510 that also includes one or more side sensor(s) 520. Essentially, side sensors can be spaced circumferentially about the plate to measure the condition of side wall SW and/or the location of the side wall. The number of side sensors can be based on the “resolution” that is desired. In this respect, the more sensors circumferentially positioned about plate 510 can increase the amount of side wall that can be accurately measured. Yet further, any number of sensor(s) 520 could be positioned centrally and could be configured to scan 360 degrees and/or rotate 360 degrees to scan side wall SW. In one embodiment, there are between about 6 and 8 sensors 520 spaced about the plate, preferably equidistantly about the central axis of the plate. Again these additional sensors can be used in combination with any embodiment of this application and, for example, device 500 can include one or more laterally facing pressure sensors 50, 52 that can operate as described above. As discussed above, sensors 520 could include multiple sensors at each location (or at least at one of the locations) to help account for, or calculate for, differences in fluid densities at different depths for boreholes that are filled with a borehole fluid to help maintain the integrity of the borehole between drilling and filling. While all of the sensors could have this feature, one embodiment includes at least one sensor with the dual sensor feature that can be used to determine the fluid density and the remaining sensor can utilize this data.
With special reference to FIG. 11, plate or unit 510 discussed above can also include one or more different types of sensors that are laterally positioned including, but not limited to, laterally facing sensors 50 x and 52 x that are actuateable laterally so that they can be forced either against or into the side wall to determine one or more physical characteristics of the side wall(s). These sensors can be pushed against the side wall to determine location and/or bearing capacity. Further, this embodiment, and others can utilize downward electronic sensor(s) 320, discussed above, for depth measurement. As a result, sensors 320 and 520 discussed above in relation to FIG. 10 can be used to measure the shape, condition and locations of the layers and side walls, while sensors 50 and 52 can measure bearing capacities of the bottom layers and sensors 50 x and 52 x can measure bearing capacities of the side wall. As with sensors 320, sensors 520 can be any sensors configured to determine surface geometries including, but not limited to sonar, radar, lasers and/or optical technologies.
Yet further, the force sensors 50, 52, 50 x and/or 52 x could be replaced by a plate which measures an average soil resistance over a wider area. Further, the device can also record a dynamic load test at varying impact speeds, by using an impact weight against a bearing plate on the drillstem. Yet further, the units of this application can include an inclinometer, accelerometer(s), and/or tilt meter to determine the angle or pitch of the bottom of the borehole. This can include, but is not limited to, the use of sensors 50, 52, 60 and/or 62 operated independently of one another to determine displacement or pressure differences that can be used to calculate pitch. As mentioned above, the number of sensors can depend on many factors including desired accuracies, costs and the use of the sensors wherein determination of characteristics, such as pitch, could necessitate more sensors. Accordingly, while it may be preferred that three sensors be used, it is not required. Yet further, the system can utilize other technologies, such as GPS, that can be used to locate and mark which hole in the construction site is being tested. This data can be utilized to organize test data for future use or review. The GPS can be any position locating system such as satellite based positioning systems and jobsite based location systems. These other sensors, such as the side sensors noted above, can also be used to determine the position of the unit within the boreholes, such as whether the device is centered within the one borehole. Yet further, gyroscopic and/or geomagnetic based systems can be utilized to track movement of the systems within the borehole.
Yet further, as is noted above, the borehole inspection and testing devices of this application could be joined to a wide range of support structures and these even include a dedicated support system wherein the inspection and testing device could be left in place for permanent pressure monitoring, which is particularly useful in conjunction with hydraulic pressure measurement systems which have the ability of accurately sensing the pressures applied by a structure to the foundation. In addition, the inspection and testing devices of this application could be used without a Kelly bar or drill stems without detracting from the invention of this application. Yet further, the inspection and testing device can also be configured to extract samples of the debris/bearing layer. This can be done with a wide range of systems including, but not limited to, one or more hollow penetrometers (not shown).
With reference to FIGS. 12-14, shown is a borehole inspection and testing device 600 having a head unit 610 that is joined relative to a cleanout bucket 612. This particular embodiment allows a single device to both remove debris from the bottom of the borehole and test the layers at bottom of the borehole as are discussed in greater detail above. As can be appreciated, this can further streamline the process of preparing and testing the borehole bottom by eliminating change over times between the use of the cleanout bucket and the inspection and testing devices of this application.
In greater detail, system 600 can include an annular extension ring 620 that can move relative to cleanout bucket 612. Ring 620 can include one or more sensor similar to one or more of the sensors discussed in greater detail above with respect to any of the disclosed embodiments. In the particular example shown, head unit 610 can include one or more force sensors 650 and 652 that can be similar to force sensors 50 and 52 discussed in greater detail above and/or one or more displacement sensors 660 and 662 that can be similar to displacement sensors 60 and 62 also discussed in greater detail above. While this example includes a four sensor arrangement, any number of sensors could be used without detracting from the invention of this application. Yet further, even side wall sensors could be utilized in this embodiment. And, the side wall sensors could be separate from extension ring 620.
Head unit 610 can further include a support ring 630 that can be joined to extension ring 620 by one or more actuation devices 632 that allow ring 620 and sensors 650, 652, 660, 662 to move relative to support ring 630 and bucket 612 along axis 636. Actuation devices 632 can be any actuation devices including, but not limited to, hydraulic and/or pneumatic cylinders. System 600 can further include a shielding apparatus 638 to protect head unit 610. This is particularly important when device 600 is lowered into borehole O and during the operation of the cleanout bucket. The shielding apparatus can include an upper shield 640 that can be formed by a top wall 642 and a side wall 644. In the embodiment shown, the side wall is a single cylindrical side wall, but this is not required. In addition, shielding apparatus can further include a bottom protective ring 646. Bottom protection ring 646 can be joined to side wall 644 or to the head unit. Further, ring 646 can include ring openings 648 that allow the sensors to retract into shielding apparatus 638 when the testing unit is not in use there by further protecting the equipment of the testing unit.
In operation, head unit can moves between a retracted position 668 as is shown in FIG. 12, wherein head unit 610 and the sensors are spaced from a working end 670 of bucket 612. This allows bucket 612 to be utilized to remove debris from the borehole without damaging the head unit.
FIG. 13 shows system 600 in an extended position 669 wherein system 600 can measure the bottom layers of the boreholes as is discussed in greater detail above. Further, actuators 632 can be utilized to produce the downward force and/or movement of the sensors for the testing of the borehole layers.
The exemplary embodiment has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

It is claimed:

1. A borehole inspection device to measure the condition of a bottom extent of a borehole including measuring a debris layer depth of a debris layer on a bottom extent of a borehole and/or a bearing layer load capacity of a bearing layer of the material below the debris layer, the inspection device comprising a head unit assembly configured to be operably joined to an associated lowering unit to lower the head unit into an associated borehole, the head unit having a top side and a generally opposite bottom side, the bottom side facing a bottom extent of the associated borehole, the head unit further including at least one downwardly extending force sensor extending downwardly relatively to the bottom side and having a distal end extending toward the associated bottom extent, the at least one downwardly extending force sensor configured to measure a reaction force applied to the at least one sensor as it engages the associated bottom extent of the associated borehole, the inspection device being configured to be lowered into an associated borehole by the associated lowering unit and to bring the at least one downwardly extending sensor into contact with the associated bottom extent of the associated borehole, continued downward movement of the head unit creating the reaction force on the least one downwardly extending force sensor to determine at least one of a location of an associated debris layer, a bearing capacity of the associated debris layer, the thickness of the associated debris layer, the location of an associated bearing layer and/or the bearing capacity of the associated bearing layer.

2. The borehole inspection device of claim 1 wherein the at least one downwardly facing force sensor includes at least one of a strain sensor and a pressure sensor.

3. The borehole inspection device of claim 1 wherein each of the at least one downwardly facing force sensor includes a base end and a downwardly facing distal end, the distal end having a conical end configuration.

4. The borehole inspection device of claim 3 further including at least one displacement sensor, the at least one displacement sensor configured to move relative to the head unit and measure downward displacement of the device after the at least one displacement sensor engages the associated bottom extent of the associated borehole.

5. The borehole inspection device of claim 3 further including at least one displacement sensor, the at least one displacement sensor including an electronic sensor unit including at least one of sonar, radar, lasers and optical technologies to measure distance between the head unit and at least one surface of the associated borehole.

6. The borehole inspection device of claim 5 wherein the at least one displacement sensor includes a downwardly facing displacement sensor to measure distance between the head unit and the associated bottom extent.

7. The borehole inspection device of claim 5 wherein the at least one displacement sensor includes a laterally facing displacement sensor to measure distance between the head unit and a side wall of the associated borehole.

8. The borehole inspection device of claim 1 further including at least one displacement sensor, the at least one displacement sensor configured to move relative to the head unit and measure downward displacement of the device after the at least one displacement sensor engages the associated bottom extent of the associated borehole.

9. The borehole inspection device of claim 1 further including at least one displacement sensor, the at least one displacement sensor including an electronic sensor unit including at least one of sonar, radar, lasers and optical technologies to measure distance between the head unit and at least one surface of the associated borehole.

10. The borehole inspection device of claim 9 wherein the at least one displacement sensor includes a downwardly facing displacement sensor to measure distance between the head unit and the associated bottom extent.

11. The borehole inspection device of claim 9 wherein the at least one displacement sensor includes a laterally facing displacement sensor to measure distance between the head unit and a side wall of the associated borehole.

12. The borehole inspection device of claim 1 wherein the associated lowering unit is an associated Kelley bar and the system further including a selectively securing mounting arrangement to secure the head unit to the associated Kelley bar.

13. The borehole inspection device of claim 1 further including a computer system having a data input, the data input being operably connected to the head unit to collect sensor data produced by the head unit.

14. The borehole inspection device of claim 13 wherein the computer system is spaced from the head unit.

15. The borehole inspection device of claim 13 further including at least one displacement sensor, the at least one displacement sensor configured to measure the distance between the head unit and the associated bottom extent.

16. The borehole inspection device of claim 1 further including at least one laterally facing force sensor that is selectively laterally extendable from the head unit assembly, the at least one laterally extending force sensor configured to measure a reaction force applied to the at least one lateral sensor as it engages an associated side wall of the associated borehole.

17. The borehole inspection device of claim 16 wherein the at least one laterally facing force sensor includes at least one of a strain sensor and a pressure sensor.

18. The borehole inspection device of claim 17 wherein each of the at least one laterally facing force sensor includes a base end and a downwardly facing distal end, the distal end having a conical end configuration.

19. A method of inspecting a condition of a bottom extent of a borehole including measuring a debris layer depth of a debris layer on a bottom extent of a borehole and/or a bearing layer load capacity of a bearing layer of the material below the debris layer, the method including the steps of:

providing an inspection device comprising a head unit assembly configured to be operably joined to an associated lowering unit to lower the head unit into an associated borehole, the head unit having a top side and a generally opposite bottom side, the bottom side facing a bottom extent of the borehole, the head unit further including at least one downwardly extending force sensor extending downwardly relatively to the bottom side and having a distal end extending toward the bottom extent, the at least one downwardly extending force sensor configured to measure a reaction force applied to the at least one force sensor as it engages the associated bottom extent of the associated borehole;

operably joining the head assembly to a lowering device;

lowering the head assembly into the borehole by way of the lowering unit;

continuing the lowering step until the at least one downwardly extending force sensor contacts the bottom extent of the borehole;

continuing the lowering step to force the at least one downwardly extending force sensor into the bottom extent of the borehole;

measuring the reaction load to determine at least one of a location of a borehole debris layer, a bearing capacity of the borehole debris layer, the thickness of the borehole debris layer, the location of a borehole bearing layer and/or the bearing capacity of the borehole bearing layer.

20. The method of inspecting a condition of borehole of claim 16 wherein inspection device further comprises at least one displacement sensor, the method further including the step of measuring the displacement of the at least one displacement sensor to track the penetration of the least one downwardly extending force sensor into the bottom of the borehole,

21. A method of inspecting a condition of a bottom extent of a borehole including measuring a debris layer depth of a debris layer on a bottom extent of a borehole and/or a bearing layer load capacity of a bearing layer of the material below the debris layer, the method including the steps of:

providing an inspection device comprising a head unit assembly configured to be operably joined to an associated lowering unit to lower the head unit into an associated borehole, the head unit having a top side and a generally opposite bottom side, the bottom side facing a bottom extent of the borehole, the head unit further including at least one downwardly extending force sensor extending downwardly relatively to the bottom side and having a distal end extending toward the bottom extent, the at least one downwardly extending force sensor configured to measure a reaction force applied to the at least one force sensor as it engages the associated bottom extent of the associated borehole, the inspection device further including at least one displacement sensor, the at least one displacement sensor configured to measure the distance between the head unit and the associated bottom extent;

operably joining the head assembly to a lowering device;

lowering the head assembly into the borehole by way of the lowering unit;

continuing the lowering step to force the at least one displacement sensor engages the bottom extent of the borehole;

marking the top surface of the bottom extent of the borehole with the at least one displacement sensor;

continuing the lower step to urge the at least one force sensor into the bottom extent; and,

measuring the reaction load on the at least one force sensor to determine at least one of a bearing capacity of the borehole debris layer, the thickness of the borehole debris layer, the location of a borehole bearing layer and/or the bearing capacity of the borehole bearing layer.