HK1105675B - An apparatus for use with a penetration assembly for hammering a sampler into ground in a drill hole - Google Patents

Description

apparatus for driving a sampler into the ground in a borehole for use in a penetration assembly

Technical Field

The present invention relates to improved methods of subsurface exploration, and more particularly to an automated apparatus and method for performing a SPT test.

Background

Standard Penetration Testing (SPT) is a field testing technique in which a sampler 20 is driven into the ground 14 at the bottom end 16 of a drill hole (or borehole) 15 during a subterranean exploration. The resistance to penetration of the soil by a free falling hammer from a constant height can be measured by experiment.

The test operation was performed by two operators. As shown in fig. 1 and 2, a first operator uses the power of a wireline 12 on a rig 10 and a rig 11 to lift or lower a hook 13 of an elevator. The second operator couples or decouples the hook of the elevator to the top of the drill rod (fig. 1) or to the steel chain 25 (fig. 2) of the impact hammer apparatus. The impact hammer apparatus comprises a steel chain, an X-clamp 24, a hammer 23 and a guide bar 26. The guide bar has a lower anvil 28 at its bottom, an upper anvil 27 at its top and a steel chain 25. The hammer has a cover 29 which is held by the X-clamp. After the following three processes are performed in real time sequence, the test is performed at the depth of the drill hole.

First, a sampler coupled in series to a drill pipe must be inserted into the borehole (fig. 1). The sampler must reach the bottom of the drill hole. If the length of the drill rod 22 with its bottom end 16 coupled to the sampler 21 is such that the sampler 20 tip does not reach the drill hole bottom, a second drill rod is added to the top of the first drill rod to bring the sampler tip to the drill hole bottom. Similarly, if the sampler tip still cannot reach the bottom of the drill hole, a third drill rod will be added and coupled. This addition, coupling and insertion process is repeated until the sampler tip reaches the bottom of the drill hole. This process is the first process of sampler insertion.

Next, once the sampler is placed at the test depth, a strike hammer apparatus will be added to the top of the coupled drill rod and sampler system. The hammer impact device will be used to penetrate the sampler into the ground at the bottom of the drill hole (fig. 2). The hook of the elevator will lift the X-clamp upwards via the steel chain. The X-clamp will grip the cap of the hammer and transport the hammer up the guide rod. Once the X-clamp strikes the upper anvil, the clamping device at the cap of the hammer will be forced to automatically open and release the hammer. The hammer will fall freely along the guide rod. The flat bottom surface of the hammer will strike the flat top surface of the lower anvil. The bottom of the lower anvil is coupled to the drill rod. The resulting impact force in the drill rod will cause the sampler to penetrate into the ground below the bottom of the drill hole. Once the hammer is stabilized on the lower anvil, the first operator will drop the elevator hook so that the X-clamp falls along the guide rod onto the cap of the hammer. Subsequently, the operator will tighten the steel chain to re-couple the X-clamp with the cap of the hammer. The operator will then quickly lift the hammer. Once the X-clamp strikes the upper anvil, the hammer will again fall freely. The hammer will hit the lower anvil so that the sampler penetrates the soil again. Repeating the above operation process for multiple times until the test standard is met. This process is the second process of hammer impact and sampler penetration.

Again, once the penetration phase is completed, the operator will remove the hammer impact device from the drill rod. The operator will then retrieve the drill rods from the drill hole one by one (fig. 1). The drill pipe and sampler will be lifted. The top drill rod will then be uncoupled from the remaining drill rods in the drill hole and it will be placed on the adjacent ground. The remaining drill pipe will then be removed from the drill hole. The second top drill rod will be uncoupled and placed on the adjacent ground. This lifting, uncoupling and setting process will be repeated until the first drill rod and sampler are retrieved from the drill hole. This process is the third process of sampler retrieval. Further drilling operations will then be performed until the bottom end of the drilled hole reaches the subsequent test depth. Subsequently, after the above three processes are performed, the subsequent tests will be performed.

The hammer is made of steel and weighs 63.5 kg. The free fall height was 760 mm. The number of hammering impacts on the anvil per 75mm penetration between 0 and 450mm was recorded. The first penetration 150mm is regarded as a stationary drive. The number of blows required to drive the sampler to penetrate 300mm into the ground is known as the penetration resistance or N value. The official body often adopts technical specifications how to determine the N value to determine the soil shear strength and bearing capacity. Hammer efficiency can be further defined as the percentage of the total potential energy (473 joules) of the rod kinetic energy to the hammer drop height. The kinetic energy of the rod is calculated from the axial impact force generated in the drill rod due to hammering according to a specific formula, such as the formula in ASTM (1995).

The SPT is widely used and is the tool of choice in hong Kong housing and infrastructure development and landslide prevention programs. The SPT is included in most land survey contracts. The SPT has the following advantages: a) the test equipment is simple and firm; b) tests can be carried out in a variety of different types of soil; c) this test is widely used worldwide as a routine field test method; and d) a great deal of experience and empirical relationships have been accumulated with respect to geotechnical design and construction.

However, the results of the SPT, and more specifically the N-value and the test depth, were obtained entirely by manual measurement. Typically, manual measurements are performed by two contractors. For most experiments, there is insufficient time for independent supervision or inspection. Furthermore, testing and drilling are destructive, non-repeatable and time consuming. More importantly, in hong Kong, tests are usually performed in collapsed layers and weathered rock soils. Gravel, cobbles and pebbles having high strength and hardness may be randomly present in the soil. They may significantly change the value of N. As a result, the N value may vary over a wide range at the construction site of hong kong.

Therefore, the accuracy and quality of the manual test results has always been a major concern for many geotechnical engineers and contractors in hong Kong. Currently, there is no tool to independently check and verify the accuracy and quality of manual test results. Thus, it is believed that automating the monitoring and recording of SPT measurements solves the pressing problem and provides additional data for independently checking and validating manual test results.

Disclosure of Invention

The problems of field observation and manual operation and measurement from conventional SPT have led to the present invention being made to automate the measurement of tests. The insertion process, the impact hammer and sampler penetration process, and the withdrawal process are performed in time series order. It is a first object of the present invention to provide an automated digital SPT monitor that records and evaluates the insertion process of a rod and sampler into a drill hole in real time, which enables the evaluation and verification of the test depth and its start time. A second object of the present invention is to provide an automated digital penetration test monitor for recording and evaluating in real time the penetration process of impact hammers and samplers, which enables the evaluation of soil resistance and more particularly the evaluation of N-value and related hammer efficiency according to the technical specification (which in this configuration is the hong kong house official specification). A third object of the present invention is to provide an automatic digital SPT monitor that records and evaluates the process of retrieving a rod and sampler from a drill hole in real time, which enables the evaluation and verification of the test depth and its completion time.

To achieve the above objects, the present invention provides a digital SPT monitor for field testing of SPTs associated with existing SPT equipment and processes. The digital SPT monitor includes a tip depth transducer, an impact force transducer, an impact penetration transducer, and a microprocessor controller for data acquisition and processing. The microprocessor controller includes a notebook computer, a data logger, and a battery. The data recorder is connected with the tip depth transducer, the impact force transducer and the impact penetration transducer through a first signal cable, a second signal cable and a third signal cable to respectively transmit a first electric signal, a second electric signal and a third electric signal. The first electrical signal and the third electrical signal are digital signals. The second electrical signal is an analog signal.

The tip depth transducer is mounted on top of the drill hole casing and unlocked just prior to the insertion process. The tip depth transducer senses vertical movement (or lack thereof) of the sampler and each of the associated drill rods relative to a fixed position on the earth (i.e., the casing) during insertion and passes the first electrical signal into the micro-process controller for storage and display in real time at a first pre-selected sampling rate. At the completion of the insertion process, the tip depth transducer is locked and removed from the casing and placed on the adjacent ground. The locking is such that the first electrical signal does not change over time.

Subsequently, the impact hammer apparatus is sequentially mounted on the top of the drill rod together with the impact force transducer and the impact penetration transducer to perform the second process of impact hammer and sampler penetration. The shock force transducer senses the axial force in the rod and the shock penetration transducer senses the displacement of the rod relative to a fixed location on the ground. They transmit the second electrical signal and the third electrical signal to the microprocessor controller via the second cable and the third cable simultaneously and in real time. Data is acquired and stored in the microprocessor controller for a preselected duration at a second preselected sampling rate using a triggering method. The triggering criteria is that the impact force is equal to or greater than a preselected magnitude of compression. The preselected data acquisition interval is less than the time interval for hammer lift and drop and greater than the time interval for hammer rebound. At the same time, the micro-process controller counts the blows and records a blow. This automatic monitoring and data acquisition process is repeated for each hammer blow until the microprocessor controller finds that the test has reached a predetermined criterion for the value of N. At this point, the computer of the micro-process controller alerts the operator. After completion of the second process, removing the impact hammer apparatus, the impact force transducer and the impact penetration transducer from the drill rod.

At the beginning of the retraction process, the tip depth transducer is reinstalled on the casing and unlocked. The tip depth transducer senses vertical movement or non-movement of the sampler and each of the coupled drill rods relative to a fixed position on the ground (i.e., the casing) during the retrieval and continues to transmit the first electrical signal into the microprocessor controller for storage and display in real time at the first pre-selected sampling rate. Upon completion of the retraction process, the tip depth transducer is again locked and removed from the casing and placed on the adjacent ground.

In this configuration, the preselected first sampling rate of the first electrical signal is 100Hz and the preselected second sampling rates of the second and third electrical signals is 50 kHz; the preselected magnitude of the triggering axial force is 50 kN; and the preselected duration of data acquisition for the second electrical signal and the third electrical signal is 1 second.

The present invention is portable and is suitable for use with any existing SPT equipment. The invention monitors three test processes in real time. The invention further evaluates SPT measurements in real-time order and reports summary test results on monitored digital data. The invention is applicable to any of a variety of land conditions including extremely hard (N > 200), normal (1 < N < 200) and extremely soft (e.g., N < 1) land conditions.

Drawings

The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a prior art manual apparatus for a first process of inserting a sample coupled in series with a drill pipe into a drilled hole (or a third process of retrieving a sample from the drilled hole) to perform a SPT at a given test depth in the field;

FIG. 2 shows a prior art apparatus for hammer and sampler penetration at the bottom of a drill hole to determine soil N-values in situ;

FIG. 3 is a general schematic view of the measurement, automation and recording of the first process of sampler insertion or the third process of sample retrieval of the present invention;

FIG. 4 is a general schematic view of a measuring, automation and recording apparatus of a second process of impact hammer and sample penetration according to the present invention;

FIG. 5 is a detailed schematic view of the measurement, automation and recording of the first process of sampler insertion or the third process of sample retrieval of the present invention;

FIG. 6 is a detailed schematic diagram of the tip depth transducer of the present invention;

FIG. 7 is an example of actual measurements made by the tip depth transducer of the present invention in real time sequence during a first pass of sample insertion and a third pass of sample retraction;

FIG. 8 is a detailed schematic of the measurement, automation and recording of the second process of impact hammer and sample penetration of the present invention;

FIG. 9 is the axial impact force in the drill rod due to impact of the hammer drop measured in situ by the impact transducer over a 1 second period;

FIG. 10 is a detailed view of the impact force results shown in FIG. 9 during its initial 0.05 second duration;

FIG. 11 is a detailed schematic view of a shock penetration transducer of the present invention;

FIG. 12 is a detailed schematic view of the gear box on the rack and along two guide rods of the shock penetration transducer of the present invention;

FIG. 13 is a graph of the change in position of the gear box on the rack sensed by the shock penetration transducer concurrently with the impact force graph shown in FIG. 9;

FIG. 14 is a detailed view of typical results of the shock penetration transducer shown in FIG. 13 during its initial 0.05 second duration; and

fig. 15 is a summary report of the measurement automation of the second process of hammer impact and sample penetration performed at the test depth shown in fig. 7.

Detailed Description

The invention will be described in further detail by way of example with reference to the accompanying drawings. As shown in fig. 3 to 8, the digital SPT monitor 10 for automating SPT measurements according to the present invention includes a microprocessor controller 30, a tip depth transducer 40, an impact force transducer 60, and an impact penetration transducer 70. The microprocessor controller 30 includes a data logger 32, a battery 33 and a notebook computer 31. The data logger 32 is attached with a power cable 34 to the battery 33 and communicates with the computer 31 with a firewall cable 35. The battery 33 is used to supply the small amount of power required by the data logger 32 and the notebook computer 31. The micro-process controller 30 further communicates with the tip depth transducer 40 using a first signal cable 36, with the shock force transducer 70 using a second signal cable 37, and with the shock penetration transducer 60 using a third signal cable 38.

Referring to fig. 5 and 6, the tip depth transducer 40 has the following components: a first circular wheel 41 with a first rotation sensor 42 and a locking device, a second circular wheel (not shown) and a third circular wheel 41 ", a hollow cylinder 43, a bottom plate 44 with a circular hole in the center, four bolts 45, four pillars 46, an inner cylinder 47, a base plate 48 with a circular hole, two springs 49 and a travel shaft 50. The first, second and third wheels 41 ", 41" are placed vertically on the base plate 48 and are spaced 120 ° apart around a common center in a horizontal plane. The legs of the travel shaft 50 are also welded to the base plate 48. The bottom surface of the shoe plate 48 is welded to the underlying hollow cylinder 43. The base of the hollow cylinder 43 is welded to the base plate 44. The upper face of the base plate 44 is welded and is welded with an inner cylinder 47 and four struts 46. The diameter of the circular holes in the bed plate and the bottom plate is larger than the diameter of the drill rod 22 and the sampler. The inner diameter of the hollow cylinder 43 is larger than the diameter of the casing. The inner diameter of the inner cylinder 47 is larger than the diameter of the drill rod and the sampler and smaller than the diameter of the casing.

The tip depth transducer 40 is placed on the casing with a bottom plate 44 and four posts are clamped to the casing with four bolts 45. Thus, the tip depth transducer 40 may be securely mounted to the top of the casing in the drill hole or may be completely removed from the top. The coupled sampler and drill rod may be inserted into or withdrawn from the tip depth transducer 40, as shown in fig. 5 and 6. In this configuration, the casing is used to support the tip depth transducer. Other means of supporting the tip depth transducer 40 may also be developed.

During insertion or retraction, the sampler or drill rod 22 makes frictional contact with the three wheels and causes them to rotate about their rotational axis. The rotational shaft of the first wheel 41 is bolted to the travel shaft 50. The first wheel 41 together with the travelling shaft 50 are horizontally movable above the bed plate. Two springs 49 force the travel shaft and first wheel against the drill stem 22 or sample. When the first wheel is turned off, the locking device stops the first wheel 41 from rotating around its axis. When the first wheel is opened, the first wheel is free to rotate about its axis.

The first electrical signal measures the degree of rotation of the first wheel 41 about its axis. The first rotation sensor 42 captures a first electrical signal and passes it into the microprocessor controller in real time through the first signal cable 36 at a first preselected sampling frequency. The micro-process controller 30 further converts the first electrical signal in real time to an amount of length of the sampler associated with the rod through the first wheel position and displays the amount of length on the notebook screen.

Fig. 7 shows a first graph of the practical results of the present invention from a first digital signal, wherein the first pre-selected sampling frequency is 100 Hz. The first graph represents the first process of sampler insertion and the third process of sampler retrieval. The test was performed between 15:14 and 15:29 pm on 29 th pm of 6/2005. The first process is between 15:14 and 15: 17. The graph shows a downward step shape over time, indicating that 4 rods are associated with the sampler to insert the sampler one by one into the borehole. The total length of the four rods and the sampler inserted through the tip depth transducer was 10.625 m. Between 15:17 and 15:25, the graph is a horizontal line, indicating that the first electrical signal does not change during the second process when the first wheel of the tip depth transducer is locked. The third process is performed between 15:25 and 15: 29. The graph shows an upward step over time, indicating that the four rods and the sampler are lifted and decoupled one by one from the drill hole. The total length of the four rods and the sampler lifted through the tip depth transducer was 11.033 m.

Referring to fig. 4 and 8, the impact force transducer 60 is connected to the lower anvil 28 by an upper coupling 52 and to the drill rod 22 at a carrier arm 81 by a lower coupling 51. The shock force transducer 60 captures the second electrical signal and transmits the second electrical signal into the micro-process controller in real time at a second pre-selected sampling frequency via the second signal cable 37. The second electrical signal is a voltage output. The micro-process controller 30 further converts the second electrical signal into the amount of axial force generated in the drill rod 22 due to hammer impact and displays the amount of axial force in real time on the screen of the personal computer 31.

Fig. 9 shows a second graph of the practical results of the present invention from a second digital signal with a second preselected sampling frequency of 50kHz and a total sampling period of 1 second. The second graph represents the time variation of the impact force in the drill rod immediately after the hammer impacts on the lower anvil. The third graph in fig. 10 shows in detail the axial impact force in the first 0.05 seconds of the second graph shown in fig. 9. From the second and third graphs of fig. 9 and 10, the following can be observed: (a) the axial impact force increases rapidly at the beginning and reaches a maximum at a time of less than 0.001 second; (b) the axial impact force vanished to zero at about 0.05 seconds; and (c) the axial impact force has a maximum value.

Referring to FIGS. 8, 11 and 12, shock penetration transducer 70 has the following major components: a right angle triangular steel frame 71 with four pulleys 72, 73, 74 and 75, a wire loop 76, a gear box 77 with a second rotation sensor, an inclined rack 78, two inclined guide rods 79, a bearing arm 81 and other accessories. During monitoring, the shock penetration transducer 60 is coupled to the drill pipe 22 by a bearing portion of a bearing arm 81, as shown in fig. 8 and 11. The shock penetration transducer 60 rests on a support beam 82 which is clamped 170 to the two sleepers 17 of the drilling rig, as shown in fig. 4.

Bearing arm 81 is coupled to traveler 76 by bolt 80 and transfers the longitudinal movement of the rod to traveler 76. The traveler 76 is supported by the first pulley 72, the second pulley 73, the third pulley 74, and the fourth pulley 75, and can slide smoothly on the four pulleys. The four pulleys are supported by a right angle triangular steel frame 71. The traveller 76 is also connected to a gear box 77 on a tilting rack 78. The gears of the gear box 77 are engaged with the gears of the rack. Two steel guide rods 79 guide the gear box 77 to move up or down on the rack 78. The rack 78 and two steel guide rods 79 are fixed with the right-angled triangular steel frame 71.

When the carrying arm moves between the first pulley 72 and the fourth pulley 75, the carrying arm 81 causes the gear box 77 to slide correspondingly on the rack between the second pulley 73 and the third pulley 74 by means of the wire loop 76. The upper part of the wire loop 76 on the first pulley 72 and the second pulley 73 between the bearing arm 81 and the gear box 77 is always straight and in tension for the reason of preventing the gear box 77 from sliding downwards on the rack 78 due to the weight of the gear box 77. The gearbox 77 typically weighs 1 to 2 kilograms. The lower portion of the wire loop 76, which is located on the third pulley 74 and the fourth pulley 75 and is interposed between the gear box 77 and the bearing arm 81, is used to quickly damp and eliminate the free vibration of the gear box 77 located on the rack 78 due to the striking action of the hammer.

A second rotation sensor associated with the gear box 77 obtains a third electrical signal and transmits it in real time through the third signal cable 38 into the micro-process controller 30 at a second pre-selected sampling frequency. The third electrical signal is the degree of rotation of the gear of the gearbox 77 on the rack 78. The micro-process controller 30 further converts the third electrical signal into the position of the gear box on the rack and displays the position on the screen of the notebook in real time. The upward movement of the gear box in its steady state is equal to the permanent penetration of the sampler due to one impact from the hammer drop.

Fig. 13 shows a fourth graph of an exemplary result of the present invention from a third digital signal, where the second preselected sampling frequency is 50kHz and the total sampling period is 1 second. This fourth graph represents the amount of time variation in the gear box position on the rack immediately after the hammer blow onto the lower anvil. The fifth graph shown in fig. 14 shows in detail the position of the gearbox within the first 0.05 seconds of the fourth graph of fig. 13. From the fourth graph shown in fig. 13 and the fifth graph shown in fig. 14, the following can be observed: (i) the change in gearbox position due to hammering disappeared within 0.2 seconds; (ii) initially, the gearbox monotonically rose to a maximum value at a time between 0.045 and 0.005 seconds; (iii) subsequently, the gear box makes a first downward movement; (iv) subsequently, the gearbox experiences a slight vibration with an amplitude of less than 2 mm; and (v) after about 0.2 seconds, the position of the gearbox is time invariant and rests at a position 22mm above the initial position.

The time in the second graph shown in fig. 9 is identical to the time in the fourth graph shown in fig. 13. The time in the third graph shown in fig. 10 is identical to the time in the fifth graph shown in fig. 14. The micro-process controller 30 simultaneously collects the second electrical signal and the third electrical signal at a second pre-selected time sampling frequency in real time sequence. The micro-process controller 30 also records the actual start times (i.e., time zero) in the graphs shown in fig. 9, 10, 13, and 14 in the form of years, days, hours, minutes, and seconds, which are omitted in these figures.

In addition, the microprocessor controller 30 of the present invention has a triggering mechanism for data acquisition and storage of the second and third electrical signals in real time. The criteria for the triggering mechanism is that the impact force from the impact force transducer 60 is equal to or greater than a preselected magnitude of compression (50 kN in this configuration). Once the impact force reaches a preselected or predetermined level, the microprocessor controller 30 acquires, stores and displays the second and third signals at a second preselected sampling frequency (50 kN in this configuration) for a preselected period of time (1 second in this configuration). At the same time, the micro-process controller 30 records the actual start time of one hammer blow and data acquisition, and checks the accumulated permanent penetration and the accumulated number of hammer blows by a predetermined specification to issue an alarm of completion of the test. This automatic monitoring and data acquisition process is repeated for each hammer blow until the micro-process controller 30 finds that the trial has reached a predetermined specification. At this point, the micro-process controller 30 alerts the operator of the completion of the test.

FIG. 15 shows a summary report of the present invention implementing the measurement automation of the second process of hammer peening and sampler penetration at the test depth shown in FIG. 7. Once the test is complete, the microprocessor controller 30 generates and displays the summary report. In fig. 15, the actual date, start and end times of the second course of the trial are reported. The table shows the number of blows used for a 150mm fixed drive followed by each 75mm active drive. The N value, total number of blows and total penetration depth are listed.

Fig. 15 also shows a sixth graph, a seventh graph and an eighth graph. The results shown in the sixth and seventh graphs are simultaneously obtained from the second and third electrical signals, respectively. The micro-process controller 30 is triggered 27 times to acquire data and evaluate at that test depth. Each time a hammer blow is applied to the lower anvil shown in fig. 4. The total time of data acquisition, which is the abscissa of the sixth graph and the seventh graph, is 27 seconds. Therefore, 27 hammering times are counted in fig. 15.

The actual start time of each 1 second sampling period is recorded but not shown in the sixth and seventh graphs. The portion of the sixth graph shown in fig. 15 between any two adjacent integer seconds in time (i.e., [0, 1] [1, 2], [26, 27]) represents the temporal variation of the axial impact force during a preselected sampling period of 1 second for each of the 27 hammers. Similarly, the portions of the seventh graph shown in fig. 15 between any two adjacent integer seconds of time (i.e., [0, 1] [1, 2], [26, 27]) represent the corresponding temporal change in the position of the gearbox during a preselected sampling period of 1 second for each of the 27 hammers. The temporal changes in axial force during each of the 27 1 second data acquisition cycles can be represented as those shown in the second graph of fig. 9 and the third graph of fig. 10. The time variation of the corresponding gearbox position during each of the 27 1 second data acquisition cycles can also be represented as those variations shown in the fourth graph of fig. 13 and the fifth graph of fig. 14, respectively. All of these graphs may be generated in the microprocessor controller.

The micro-process controller also calculates the energy efficiency (%) of each hammering from the impact force acquired in the sixth graph, and represents and displays the hammering energy efficiency corresponding to the respective number of hammering in the eighth graph on the computer screen.

Reference to the literature

The following references are incorporated herein by reference as illustrative of the present technology:

1.ASTM，1995.Soil and Rock(1)，Vol.04.08:Standard Test Method forPenetration Test and Split-Barrel Sampling of Soils，D 1586-84，1916 RaceStreet，PhiladeIphia，U.S.A.，129-133

2.ASTM，1995.Soil and Rock(1)，Vol.04.08:Standard Test Method for StressWave Energy Measurement for Dynamic Penetrometer Testing Systems，D4633-86，1916 Race Street，Philadelphia，U.S.A.，775-778.

3.GEO，1996.Section 21.2 Standard Penetration Test，in Guide to SiteInvestigation，Geoguide 2，Geotechnical Engineering Office(GEO)CivilEngineering Department，Hong Kong，pp.111-113.

4.HKHA，2003.HKHA General Specifications for Ground InvestigationContracts，2003 Edition (Revision A)，Hong Kong Housing Authority (HKHA)，Hong Kong.p.2.

5.Yue，Z.Q.，Lee，C.F.，Law，K.T.and Tham，L.G.，2004.Automaticmonitoring of rotary-percussive drilling for ground characterization-illustratedby a case example in Hong Kong，lnternational Journal of Rock Mechanics &Mining Science，41:573-612.

6.U.S.Patent No.6,637,523 B2 (Lee)

Claims (14)

1. An apparatus for hammering a sampler into a drill hole or into the ground in a borehole for use with a penetration assembly having:

a sampler having a coupler at one end to connect with a rod;

a plurality of rods, each end of the rods having a coupling for connecting itself in series;

a striking hammer apparatus which can be connected to or disconnected from the top ends of a plurality of coupling rods in series and which can be dropped from a constant height to strike the top ends of the coupling rods;

a lifting device for lifting a rod for coupling, decoupling, inserting and retracting or for lifting the impact hammer apparatus to fall down to repeatedly impact the top end of the coupling rod having the sampler at the bottom end;

the apparatus comprises:

a tip depth transducer outputting a first electrical signal that is a function of the total length of the sampler and rod coupled together in series, themselves, through a fixed reference point on top of the drill hole;

an impact force transducer that outputs a second electrical signal that is a function of an impact force in the rod and along an axial direction of the rod;

an impact penetration transducer outputting a third electrical signal that is a function of the penetration depth of the sampler due to the hammering of the impact hammer apparatus falling from a constant height; and

a controller that receives and monitors the first, second, and third electrical signals and generates respective function graph traces of the sampler tip position, the impact force of the rod, and the sampler shock penetration depth.

2. The apparatus of claim 1, wherein the controller monitors, processes, acquires, and stores the first electrical signal at a first preselected sampling frequency and generates a first graphical trace of the position of the sampler tip depth.

3. The apparatus of claim 1, wherein the controller monitors and processes the second and third electrical signals at a second preselected sampling frequency and utilizes the second electrical signal as a triggering criteria for acquiring and storing the second and third electrical signals at the second preselected sampling frequency.

4. The apparatus according to claim 1, wherein the controller evaluates the second and third electrical signals and generates an electrical signal indicative of completion of the impact hammer state.

5. The apparatus of claim 1, wherein said controller generates respective function plot trajectories of the impact force of said rod, penetration depth of said sampler.

6. The apparatus of claim 1, wherein the controller generates a summary report of monitoring results including number of hammering, impact hammer time, hammer efficiency and corresponding sampler penetration depth.

7. The apparatus of claim 1, wherein a device monitors, acquires, and processes the first, second, and third electrical signals and generates the graphical trace in real time during the sampler insertion process, the impact hammer apparatus impact and sampler penetration process, and/or the sampler retrieval process.

8. The apparatus of claim 1, wherein the first electrical signal and the third electrical signal are digital signals.

9. The apparatus of claim 1, wherein the second electrical signal is an analog signal.

10. The apparatus of claim 1, wherein the tip depth transducer comprises:

a first wheel, a second wheel and a third wheel mounted on the movable vertical axis of the casing;

the first, second and third wheels are rotatable about their respective axes;

at least one spring for urging the first wheel against the vertical shaft;

a first rotation sensor operatively connected to the vertical shaft to measure rotation of the first wheel due to upward or downward movement of the vertical shaft;

wherein the first rotation sensor captures the first electrical signal.

11. The apparatus of claim 10, wherein the first, second, and third wheels are vertically and securely placed above the casing and are 120 ° spaced about the vertical axis in a horizontal plane.

12. The apparatus of claim 10, wherein the first wheel carries the first rotation sensor for outputting the first electrical signal as a function of a pass length.

13. The apparatus of claim 1, wherein the shock penetration transducer comprises:

a rigid right-angled triangular metal frame with four pulleys attached, one of the two legs of the frame being securely mounted to a horizontal beam fixed to the ground to vertically erect the second leg;

a wire loop;

a gear case;

a second rotation sensor;

a rack fixed on the oblique side of the right-angled triangular metal frame to make a gear on the rack regularly rotate and make the gear box move;

two guide rods fixed on the oblique sides of the right-angled triangular metal frame to guide the gear box to stably move on the rack; and

a carrying arm;

wherein the wire loop rests on and moves smoothly over the four pulleys of the right triangle metal frame and fastens the gear box in series above and parallel to the rack, pushing the gear box to turn and move on the rack in the direction of the two guide rods.

14. The apparatus of claim 13, wherein the second rotation sensor is coupled to a gear shaft in the gear box and is in communication with rotation of the gear on the rack to output the third electrical signal as a function of the gear box position on the rack.