CZ31344U1 - The CCBM type probe for measurement of strain changes in rock masses, especially for long-term measurements - Google Patents

Description

Technical field

The technical solution relates to a CCBM type probe for measuring stress variations in the rock mass, especially for long-term measurements.

BACKGROUND OF THE INVENTION

Measurement and monitoring of rock mass stress in situ represent one of the fundamental tasks of mining geomechanics. For example, stress measurements are needed to classify the rock mass quality using the Q indexing system. Data on the rock mass stress condition are then crucial to addressing the behavior of the rock mass when interacting with underground parts, such as stability and reinforcement, stress, orientation and shape of underground spaces with respect to applied stresses, etc.

Hydrofracturing is often used to measure the rock mass stress, but it is not possible to determine the complete stress tensor, but only the horizontal components of the stress field. The CCBO (Compact Conical-ended Borehole Overcoring) method using a cone probe to measure absolute stress magnitude by the lightweight drill core (CCBM) method and the CCBM (Compact Conical-ended Borehole Monitoring) based on a tapered probe for measuring and long-term change monitoring Tension. The principle of these methods is to measure the deformation of rock on the borehole face in independent directions, caused by its relief (drilling) or long-term monitoring of changes in measured deformations. Deformation is measured using strain gauges glued to the borehole / probe wall, shaped as a conical surface. On the basis of deformations measured in independent directions and deformation properties of rock, magnitude and directions of main stresses of rock mass are calculated. The installation of the CCBO and CCBM measuring probes requires grounding of the measuring bore with a special conical chisel followed by polishing the surface of the conical borehole, or a space at the bottom of the measuring borehole in which the probe is installed can be prepared. rock, respectively. dressing mixture. The object of this technical solution is to design a probe, especially of the CCBM type, for long-term measurement of stress changes in the rock mass, which would allow automatic data collection according to a predetermined time schedule and which would enable sending measured data to the central data collection device. probe systems of this type.

The essence of the technical solution

The above-mentioned task is solved by a CCBM probe for measuring stress changes in the rock mass it contains

- working end, the outer surface of which is frustoconical,

a set of strain gauges spaced apart on the conical surface of the working end, and

an electronic unit in the form of at least one printed circuit board comprising a memory module for storing location information and probe storage conditions, the strain gauges being electrically connected to the electronic unit.

Preferably, the electronic unit is in the form of an array of interconnected printed circuit boards and comprises a control unit and a memory unit for storing the measured data, the control unit and the memory unit being interconnected.

Preferably, the probe comprises an identification chip to uniquely identify the probe.

It is particularly preferred that the electronic unit comprises a real time module that is electrically connected to the control unit.

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In a particularly preferred embodiment, the probe according to the invention comprises a connection end with an input for the power cable and for the communication cable and / or with at least one socket for connection to the power supply and / or to the data storage.

In terms of installation, respectively. in operation of the probe, it is preferred that the probe further comprises a heating wire extending through the working end along its outer surface. The heating wire may be connected to the at least one tube and / or to the power cable inlet to power it.

From the viewpoint of measuring / evaluating the measured values, it is advantageous if the probe further comprises a temperature sensor arranged in the working end at its surface and connected to the electronic unit and / or to the communication cable entry and / or to at least one tube.

From an operational point of view, it is preferred that the probe further comprises an accumulator that is connectable to the electronic unit.

Also, it is preferred that the probe further comprises an intrinsically safe power supply for converting the voltage applied to the probe into a voltage usable in the electronic probe unit.

Preferably, the electronic unit further comprises

- a multiplexer which is connected to strain gauges,

- a programmable signal amplifier connected to said multiplexer,

An A / D converter connected to said programmable signal amplifier, and

a digital signal processor coupled to said A / D converter as well as to the memory unit.

Preferred embodiments are set forth in the description of exemplary embodiments and in the dependent claims.

The probe according to this technical solution is designed for long-term monitoring of tensor changes of local stress state of rock massif, based on measurement of deformations of cone bottom of borehole caused by stress changes in surrounding rock massif. The probe can be equipped with a cable for external power connection and data acquisition.

The CCBM method (CCBM) is derived from the basic CCBO methodology, whereby the drilling phase is omitted and incremental voltage tensors can be monitored.

In order to determine the exact value of stress, it is usually necessary to install the probe at a sufficient distance from the underground works and thus avoid the effects of the deformation of the stress field caused by the mine's existence itself - by changing the geomechanical situation. In the case of an exceptional installation of the probe in the influence area, this must be taken into account and the results corrected by means of a mathematical model.

Clarification of the drawing

The technical solution is further explained in more detail by means of a drawing, in which the construction of the probe according to this technical solution is schematically indicated.

Example of technical solution implementation

The rock mass measurement probe according to the present invention comprises a connection end with an input 1 for a power cable and a communication cable. Input i may be in the form of a common connector, or two connectors may be provided, one for the power cable and one for the communication cable. Power cable is given for powering the electrical components of the probe, communication cable is given for entering the program modes and transmitting data from the probe, respectively. from its electronic unit to a central data acquisition device.

Preferably, the power and communication cable input 1 is seated in a carrier plate 20, on which an intrinsically safe power supply for converting the probe voltage to the voltage usable in the electronic probe unit and intrinsically safe separation can also advantageously be provided. RS485 communication bus. Via this intrinsically safe power supply and communication bus separator, input I is connected to at least one component of the electronic unit in the probe, i.e. to at least one circuit board 10, 1T, 12, 13,14,15,16.

Preferably, the probe comprises an identification chip that allows the data to be clearly associated with the respective probe data when sending data from the probe to the central data acquisition device. to its location.

Furthermore, the probe has a working end whose outer surface is in the form of a truncated cone corresponding to the conical surface of the borehole in which the measurement is made.

On the conical surface of the working end is mounted a system of strain gauges 6 arranged with a uniform mutual spacing, in particular angular spacing. The strain gauges 6 are preferably in the form of a foil strain gauge glued to the surface of the working end of the probe.

In addition, a plurality of interconnected printed circuit boards 10, 11, 12, 11, 14, 15, 16 are arranged in the probe, forming an electronic unit comprising a control unit, a memory unit for storing measured data, a real time module and a memory module for storing location information and probe storage conditions. The electronic unit enables data acquisition from strain gauges 6 and from temperature sensor 3 and control of the operation of these elements. Due to the presence of a real-time module, the electronic unit can, in the prescribed and / or non-prescribed time limits, be able to operate the unit. at regular intervals to initiate data acquisition from strain gauges 6 and / or from temperature sensor 3 and / or initiate recording of the detected data to the memory unit, and then, based on the detected data, possibly sending data to the central data acquisition device and the like.

Preferably, the printed circuit boards 10, 11, 12, 13, 14, 15, 16 are arranged parallel to each other, extending perpendicular to the longitudinal axis of the probe and additionally spaced apart.

Preferably, the electronic unit comprises a multiplexer, a programmable signal amplifier from strain gauges 6, an A / D converter, and a digital signal processor coupled to each other in the order indicated, wherein the amplifier is also connected to the control unit. Thanks to such a configuration, it is possible to realize the choice of gain and consequently the choice of measuring range.

Further, a heating wire 7 extends along the working end along its conical surface. This heating wire 2 is connected to at least one of the tubes 25 at the connecting end and / or to the input for the power and communication cable so that it can be connected to the power cable. In addition, it is preferably connected to at least one printed circuit board 16.

Preferably, one printed circuit board 16 is disposed substantially in the narrow region of the working end perpendicular to the longitudinal axis of the probe, and the closest printed circuit board 15 is disposed parallel thereto and over a wide working end region or near the interface between the working end and the cylindrical probe body. forming the connecting end. Then, it is preferred that the heating wire 7 is guided so that it passes sequentially from the first plate 15 to the second plate 16 and back to the first plate 15 and again to the second, etc., wherein the individual attachment points to the first plate 15 are equally spaced from each other. are arranged at the periphery of the first plate 15, just as the individual attachment points to the second plate 16 are arranged with a uniform spacing at the periphery of the second plate 16.

At its working end, a temperature sensor 3 is arranged at its surface, which is connected to at least one printed circuit board 10, 11, 12, 12, 14, 15, 16, possibly with an input for a power and communication cable, and / or The temperature sensor 3 makes it possible to take into account the actual temperature during the concrete voltage measurement by means of strain gauges 6.

In the embodiment shown in the drawing, the probe also comprises an accumulator 8 whose positive pole is connected to at least one printed circuit board, preferably to the printed circuit board 13. Several of the printed circuit boards 12, 13, 14, 15 have a central opening through which the accumulator 8 passes. However, it is obvious that other arrangements can be used.

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The accumulator 8 is adapted to supply all elements of the probe. Thus, in the event of a power supply failure, the probe can switch to autonomous mode with battery power 8 and storing data in its own memory unit. When the standard mode is restored, the data from the probe memory unit is transferred via the communication cable to the central data acquisition device. This can be both an automatic distributed metering system and an operator's handheld device.

The accumulator 8 is also usable in case of using the probe in off-line mode, when the probe independently measures values at specified time intervals (eg after 15 minutes) and reading all autonomously measured data is done manually at longer time intervals (eg 1x in 14 days).

After assembling the printed circuit boards 10, 11, 12, 13,14, 15, 16 and connecting them and positioning them, for example, using a supporting structure comprising a triple column 2 and a supporting plate 20, connecting the input I for communication and power cable, mounting of the accumulator 8, the alignment of the temperature sensor 3 and the threading and connection of the heating wire 7, this assembly is placed in the jig and embedded with a sealing compound, eg silicone, epoxy or polyurethane. In particular, a conical end and, optionally, a cylindrical probe body extending from the conical end to the connecting end are formed. Preferably, the working end is first formed, which is embedded in the fixture of the desired shape with potting compound, then the remainder of the probe is assembled and in another fixture is cast to form a cylindrical probe body with a connector.

Advantageously, the sleeves 25 at the connection end may also allow interconnection with the electronic unit and the external electronic device or the external device. with data storage. Preferably, the tubes 25 are intended to feed the heating wire 7 and the temperature sensor 3 at the time of installation of the probe and the curing of the adhesive after the installation of the probe. In another measurement process, it is advantageous to use an external power supply connected to the input i or an accumulator 8 to power these components. One of the tubes 25 may advantageously be usable for data transmission during and shortly after installation, for example reading data from the identification chip. a memory module for storing the location and installation conditions of the probe and temperature sensor 3, and for transferring this data to an external device. An assembly of a pair of power supply tubes 25 and one data transmission tube 25 is also useful for mechanically attaching the probe to the insertion rod when introducing the probe into a well.

The posts 2 are preferably divided, i.e. formed of several sub-posts, each having a plug-in pin at one end and a complementary cavity at the other end for receiving the plug-in pin of another sub-pin. A printed circuit board is threaded through a hole between a pair of interconnected sub-pillars and is thus mounted between the pair of sub-pillars.

For the installation of the probe according to this technical solution, a tapered borehole is first prepared. The conical surface of the working end is coated with a suitable adhesive, for example epoxy adhesive, and seated in the prepared well. Alternatively, a grout mixture, for example of the type described in Utility Model No. 30103, is poured into a tapered borehole, and the probe is positioned therein. Subsequently, the heating is switched on with a heating wire 7 which enables / facilitates the curing of the adhesive or the grout mixture.

After curing, the heating wire 7 is switched off and the measurement itself can be started.

The operation of each of the probe components described above is controlled by software stored in the electrical unit and / or by software stored on an external device that is connected or connectable (wired or wireless) to the electronic unit.

Although a particularly advantageous exemplary embodiment and a number of possible modifications and changes thereof have been described, it is obvious that one skilled in the art will easily find other possible alternatives to these embodiments. Therefore, the scope of protection is not limited to these exemplary embodiments, but rather is given by the definition of the enclosed protection claims.

Claims (11)

PROTECTION REQUIREMENTS 1. A CCBM probe for measuring stress variations in a rock mass, in particular for long-term measurements, comprising: - working end, the outer surface of which is frustoconical, a set of strain gauges (6) spaced apart on the conical surface of the working end, and - an electronic unit in the form of at least one printed circuit board (11, 12, 13, 14, 15, 16) comprising a memory module for storing location information and probe storage conditions, the strain gauges (6) being electrically connected to the electronic unit. Probe according to claim 1, characterized in that the electronic unit is in the form of a system of interconnected printed circuit boards (11, 12, 13, 14, 15, 16) and comprises a control unit and a memory unit for storing the measured data, the unit and the memory unit are interconnected. A probe according to claim 1 or 2, characterized in that it comprises an identification chip for unique probe identification. The probe of claim 2 or 3, wherein the electronic unit comprises a real time module that is electrically connected to the control unit. Probe according to any one of the preceding claims, characterized in that it comprises a connection end with an input (1) for the power cable and for the communication cable and / or with at least one socket (25) for connection to the power supply and / or data storage. The probe of any of the preceding claims, further comprising a heating wire (7) extending through the working end along its outer surface. Probe according to claim 6, characterized in that the heating wire (7) is connected to at least one tube (25) and / or to the power cable inlet (1) for feeding it. The probe according to any one of the preceding claims, characterized in that it further comprises a temperature sensor (3) arranged at the working end at its surface and connected to the electronic unit and / or to the communication cable inlet (1) and / or at least one. a tube (25). The probe of any of the preceding claims, further comprising an accumulator (8) that is connectable to the electronic unit. The probe of any preceding claim, further comprising an intrinsically safe power supply for converting the voltage applied to the probe into a voltage usable in the electronic probe unit. The probe of any preceding claim in combination with claim 2, wherein the electronic unit further comprises - a multiplexer which is connected to strain gauges, - a programmable signal amplifier connected to said multiplexer, J, An A / D converter connected to said programmable signal amplifier, and a digital signal processor coupled to said A / D converter as well as to the memory unit.