CN110514342B - Measuring device and method for rapidly measuring ground stress of soft rock stratum - Google Patents
Measuring device and method for rapidly measuring ground stress of soft rock stratum Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 70
- 239000011435 rock Substances 0.000 title claims abstract description 41
- 238000012360 testing method Methods 0.000 claims abstract description 29
- 239000002775 capsule Substances 0.000 claims description 83
- 238000005553 drilling Methods 0.000 claims description 34
- 238000005259 measurement Methods 0.000 claims description 22
- 238000012545 processing Methods 0.000 claims description 22
- 238000004364 calculation method Methods 0.000 claims description 15
- 238000004891 communication Methods 0.000 claims description 15
- 238000004088 simulation Methods 0.000 claims description 14
- 238000011084 recovery Methods 0.000 claims description 12
- 230000005489 elastic deformation Effects 0.000 claims description 9
- 238000000572 ellipsometry Methods 0.000 claims description 9
- 239000011148 porous material Substances 0.000 claims description 5
- 238000003860 storage Methods 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 238000013215 result calculation Methods 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 claims 3
- 238000010586 diagram Methods 0.000 description 3
- 238000010998 test method Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000009662 stress testing Methods 0.000 description 2
- 238000009933 burial Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0004—Force transducers adapted for mounting in a bore of the force receiving structure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
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- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention provides a measuring device and a method for rapidly measuring the ground stress of a soft rock stratum, which are combined with the characteristics of a hydraulic fracturing method and an aperture deformation method, and consist of a closed hydraulic fracturing method pipeline system and an aperture deformation measuring system. The method can rapidly determine the ground stress of the soft rock, the magnitude and the direction of the two-dimensional main stress of the cross section of the drill hole can be obtained by single test, the sleeve drill hole releasing operation is not needed in the measuring process, the measuring time is saved by more than 50% compared with that of the hydraulic fracturing method and the aperture deformation method, and the three-dimensional stress result can be obtained by utilizing three-hole and more intersection hole systems.
Description
Technical Field
The invention relates to the field of rock-soil tests, in particular to a measuring device and a measuring method for rapidly measuring the ground stress of a soft rock stratum.
Background
The ground stress information is basic data of earthquake prediction and underground engineering building design in industries such as water and electricity, traffic, nuclear power, mining and the like, and the in-situ ground stress test is the most accurate method for acquiring the information. Currently, the main methods of the ground stress test include a surface stress measurement method, a trephine Kong Jie division method and a hydraulic fracturing method, wherein the trephine Kong Jie division method is further divided into a hole wall strain method, a hole diameter deformation method and a hole bottom strain method, and the hole wall strain method is further divided into a direct patch type and a hollow ladle type. The most widely used methods at present are the hollow inclusion removal method and the hydraulic fracturing method. Because the soft rock has obvious plastic deformation, the method is based on the elastic theory, and is only suitable for the ground stress test of the hard rock stratum.
In recent years, with the advance of China's engineering to areas with large burial depth and complicated geological conditions, the problem of large deformation of soft rock under high stress brings huge economic loss to the construction of a plurality of water-transfer projects and traffic projects, and the technology for testing the ground stress of the soft rock is also needed in the large-scale engineering construction of the current Tibetan railway and the like. Up to the present, the soft rock ground stress test method only has a 'pressure box three-dimensional stress test method based on the rheological stress recovery theory', but the defect is obvious, and the test period is far longer than 100 days. In a word, the existing soft rock ground stress testing method can not meet engineering requirements far, but other testing methods can not be applied, and the soft rock measurement technology needs to break through.
Disclosure of Invention
Aiming at the defects of the conventional soft rock ground stress testing means, the invention provides a test device and a test method for rapidly testing the soft rock stratum ground stress.
The measuring device comprises a pressing deformation subsystem and a data measuring subsystem, wherein the pressing deformation subsystem is used for carrying out full-section internal pressing on a drill hole in a special loading mode to enable an aperture to be expanded and deformed, the data measuring subsystem is used for collecting deformation data, azimuth data and pressure data of the pressing deformation subsystem in the aperture expansion and deformation, determining a ground stress state by utilizing the ground stress, the applied stress and deformation characteristics of a rock mass, carrying out ovalization simulation of aperture deformation according to the deformation data, calculating the pressure and deformation relation between the major axis direction and the minor axis direction of the deformation by combining the pressure data and the azimuth data, determining the main stress direction and the main stress magnitude of a cross section of the drill hole, and the main stress direction of the cross section of the drill hole is obtained by ovalization simulation and azimuth data of the deformation data of the drill hole in the measuring process, wherein the direction of the minimum deformation is the maximum main stress direction of the cross section; the main stress value is determined by elastic recovery deformation, elastic modulus and applied stress in the major axis direction and the minor axis direction of the deformed ellipse obtained in a special loading mode.
Further, the pressure applying deformation subsystem comprises a pressure pump, a pressure pipeline and a telescopic capsule, wherein the telescopic capsule is arranged in a measuring borehole formed by hole forming at an engineering key position, the pressure pump is connected with the telescopic capsule through the pressure pipeline, when the telescopic capsule is filled with a medium and is tightly attached to the hole wall, the telescopic capsule is radially expanded when the pressure conducting medium is pumped into the telescopic capsule through the pressure pump continuously, so that the aperture of the measuring borehole is deformed, and when the pressure pump is closed for medium backflow, the telescopic capsule is contracted;
The data measurement subsystem comprises a pressure sensor, a pressure gauge, a data acquisition instrument, a signal bin, a computer, a ranging element circumferentially arranged in the telescopic capsule and a three-dimensional electronic compass connected with the telescopic capsule, wherein the pressure sensor is used for acquiring pressure data of the telescopic capsule, the ranging element is used for detecting deformation data of a position of the ranging element in a pressurizing process, the three-dimensional electronic compass is used for detecting azimuth data beta of an X axis of the telescopic capsule, the ranging element and the three-dimensional electronic compass are connected with the data acquisition instrument through the signal bin, a signal output end of the data acquisition instrument is connected with the computer, the signal bin has data acquisition, processing and communication functions, the signal bin is connected with a first signal receiving end of the data acquisition instrument, the pressure sensor is connected with a second signal receiving end of the data acquisition instrument, and a signal output end of the data acquisition instrument is connected with the computer.
Further, a three-dimensional electronic compass, a signal processing circuit and a communication circuit are packaged in the signal bin, the ranging element and the three-dimensional electronic compass are connected with the signal processing circuit, the signal processing circuit is connected with the communication circuit, and the communication circuit is connected with a first signal receiving end of the data acquisition instrument through a signal wire; the three-dimensional electronic compass is used for providing an included angle between the measurement reference N and the X axis of the telescopic capsule, namely azimuth data beta; the signal processing circuit transmits the azimuth data and the deformation data to the acquisition instrument through the signal line by the communication circuit.
Further, the main stress direction of the cross section of the drill hole is obtained by ellipsometry simulation of drill hole deformation data and azimuth data in the measuring process, the included angle between the long axis direction and the X axis of the ellipsometry result of the aperture deformation is alpha, and the maximum main stress direction of the cross section is perpendicular to the long axis direction and is theta+/-90 degrees.
Furthermore, the special loading mode is a mode that pressurization and pressure release are in the same pressure interval, and elastic deformation is separated to calculate the main stress value.
Further, the principal stress magnitude of the borehole cross section is calculated by equation (1):
Wherein: sigma 1 is the plane maximum principal stress, sigma 2 is the plane minimum principal stress, u ae is elastic recovery deformation in the long axis direction from C 2 to C 3, u be is elastic recovery deformation in the short axis direction, and the calculation formula is shown in formula (2):
In the formula (2), u 2a and u 2b are respectively the deformation of the C 3 state to the I state in the long axis direction and the short axis direction; u a and u b are pore diameter deformations in the major and minor axis directions from the I state to the C 2 state, respectively;
μ is the poisson ratio of the rock mass, which can be estimated or obtained by auxiliary tests; r is the radius of a test drilling hole, p is the pressure difference between the state of C 1 and the state of C 2, a calculation formula is (p 2-p1), the pressure of the telescopic capsule can be set when p 1＝(pI+1)MPa,pI is in the state of I, the state of I is the initial state of the capsule tightly attached to the hole wall, and p 2 is the maximum value of the stress applied in the calculation and loading process; e is the elastic modulus of the rock mass.
Further, the elastic modulus E of the rock mass is obtained by the pressure change and elastic deformation in the states of C 2 to C 3, and can be calculated by the formula (3):
Wherein A is a coefficient related to the measuring device; u 2a and u 2b are the deformations of the C 3 state relative to the I state in the major and minor axis directions, respectively; u a and u b are deformations in the major and minor axis directions from the I state to the C 2 state, respectively.
Further, the pressure-conducting medium is a gas or a liquid.
The method for rapidly measuring the ground stress of the soft rock stratum is characterized by comprising the following steps of:
firstly, forming a measuring drilling hole at a key position of engineering, wherein the hole diameter is matched with the diameter of a telescopic capsule;
step two, after hole forming is completed, connecting a pressure applying deformation pipeline and a data measuring pipeline, and selecting to determine the hole depth to put into a telescopic capsule and a signal bin, wherein the telescopic capsule is connected with a pressure pump through a pressure pipeline, and a pressure sensor and a pressure gauge are arranged on the pressure pipeline; the three-dimensional electronic compass is used for detecting the azimuth data beta of the X-axis direction of the telescopic capsule;
pumping a medium into a pressure pipeline by a pressure pump to enable the telescopic capsule to expand and deform until the telescopic capsule completely fits the wall of a measuring borehole, then carrying out a loading test of a calculation process, acquiring and recording pressure data, deformation data and azimuth data in the whole process, and transmitting the pressure data, the deformation data and the azimuth data to a computer for storage, processing and display by a data acquisition instrument;
and fourthly, calculating results by test data, namely, obtaining the main stress direction of the cross section of the drilling hole by ellipsometry simulation of deformation data and azimuth data of the drilling hole in the measuring process, wherein the main stress magnitude is determined by elastic recovery deformation, elastic modulus, applied stress and the like in the long axis direction and the short axis direction which are obtained in a special loading mode.
According to the invention, the characteristics of the hydraulic fracturing method and the aperture deformation method are combined, the ground stress of the soft rock is measured according to the ground stress, the applied stress and the deformation characteristics of the rock, the aperture deformation is caused by adopting a special loading mode, the maximum main stress direction is obtained by carrying out ovalization simulation on the aperture deformation, the elastic deformation is separated to carry out ground stress value calculation, the two-dimensional stress value and direction of the cross section of the drill hole can be obtained by single test, the sleeve drilling release operation is not needed in the measuring process, the measuring time can be saved by more than 50 percent compared with the hydraulic fracturing method and the aperture deformation method, and the three-dimensional stress result can be obtained by utilizing three holes and more than intersection hole systems.
Drawings
FIG. 1 is a schematic diagram of a device for rapidly measuring the ground stress of a soft rock stratum according to the invention;
FIG. 2 is a schematic structural view of the telescopic capsule of the present invention;
FIG. 3 is a schematic diagram showing the variation of the cross section of the capsule and the aperture in the pressurizing process, wherein the state 0 is the cross section of the capsule in the unexpanded state, and the states I and E are the cross section of the drilling hole in the pressurizing state and the maximum pressurizing state when the pressurizing state is close to the hole wall; the o-xy is a coordinate system of a drilling hole and a telescopic capsule, the x-axis is a measurement target of the three-dimensional electronic compass, the N is a measurement reference of the three-dimensional electronic compass, the vertical hole is generally taken as the northbound direction, and the horizontal drilling hole is taken as the horizontal direction;
FIG. 4 is a schematic diagram showing the relationship between the states of the measuring process according to the present invention, wherein I and E are the borehole cross-sectional shapes of the state of pressing against the hole wall and the state of extreme pressing, and C 1、C2 and C 3 are the borehole cross-sectional shapes of the initial state, the state of maximum pressing and the state of recovery to the pressure p 1 during the measuring and calculating process;
FIG. 5 is a graph of capsule pressure versus pore size deformation in the major and minor axes directions of the present invention.
In the figure: 1-computer, 1-2-data acquisition instrument, 1-3-pressure meter, 1-4-pressure sensor and 1-5-booster pump; 2-1-pressure pipeline and 2-signal line; 3-1-telescopic capsule, 3-2-distance measuring element, 3-signal bin, 3-4-skeleton, 4-measuring drilling.
Detailed Description
The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings.
Referring to fig. 1 and 2, the measuring device for rapidly measuring the ground stress of a soft rock stratum of the invention comprises a closed hydraulic fracturing method pipeline system and an aperture deformation measuring system, in particular a pressure applying deformation subsystem and a data measuring subsystem, wherein the pressure applying deformation subsystem comprises a pressure pump 1-5, a pressure pipeline 2-1 and a telescopic capsule 3-1, the telescopic capsule 3-1 is arranged in a measuring drilling hole 4 formed by hole forming at an engineering key position, and the diameter of the measuring drilling hole 4 is matched with that of the telescopic capsule 3-1; the pressure pump 1-5 is connected with the telescopic capsule 3-1 through a pressure pipeline 2-1. When the telescopic capsule 3-1 is filled with medium, liquid or gas, the telescopic capsule 3-1 expands radially when the medium is pumped continuously through the pressure pump 1-5, the deformation of the bore diameter of the measuring drill is forced, the medium reflux of the pressure pump 1-5 is closed, and the telescopic capsule 3-1 contracts.
The data measurement subsystem comprises a pressure sensor 1-4, a pressure gauge 1-3, a data acquisition instrument 1-2, a computer 1-1, a distance measuring element 3-2 arranged in a telescopic capsule 3-1 and a signal bin 3-3 connected with the telescopic capsule 3-1, wherein a three-dimensional electronic compass, a signal processing circuit, a communication circuit and the like are packaged in the signal bin 3-3. The ranging element 3-2 and the three-dimensional electronic compass are connected with a signal processing circuit in the signal bin, the signal processing circuit is connected with a communication circuit, and the communication circuit is connected with a first signal receiving end of the data acquisition instrument 1-2 through a signal wire 2-2; the pressure sensor 1-4 and the pressure gauge 1-3 are arranged on the pressure pipeline 2-1, the pressure sensor 1-4 is connected with a second signal receiving end of the data acquisition instrument 1-2, and a signal output end of the data acquisition instrument 1-2 is connected with the computer 1-1.
The three-dimensional electronic compass can give out the spatial position of the telescopic capsule, and the measuring standard N in the drilling section of the three-dimensional electronic compass can give out the azimuth data of the X axis of the telescopic capsule 3-1. The ranging elements 3-2 can adopt a measuring mode of various principles such as a linear displacement meter, a laser range finder and the like, are circumferentially arranged in the telescopic capsule 3-1, the more and the better the number, the more the ranging elements 3-2 are used for detecting deformation data of the part of the telescopic capsule 3-1 where the ranging elements 3-2 are located in the pressurizing process, and the deformation data and the circumferentially arranged data of all the ranging elements 3-2 are utilized for carrying out ovalization processing on aperture deformation, so that the deformation data of the telescopic capsule 3-1 relative to an X axis can be obtained and are equivalent to the aperture deformation data. The pressure sensor 1-4 is used for collecting pressure data of the telescopic capsule 3-1.
The signal bin 3-3 has the functions of collecting, processing information such as the orientation and deformation signals of the telescopic capsule 3-1, communicating with the ground computer 1-1 and the like. The azimuth data of the telescopic capsule 3-1X axis provided by the three-dimensional electronic compass and the deformation data acquired by the ranging element 3-2 are processed by a signal processing circuit of the signal bin 3-3, then transmitted to the acquisition instrument 1-2 by the signal wire 2-2, and then transmitted to the computer 1-1 for storage, processing and display, and the pressure data acquired by the pressure sensor 1-4 is also transmitted to the computer 1-1. The computer 1-1 is used for storing the measurement data, and application software is installed in the computer 1-1 to perform aperture deformation ellipsometry simulation, calculate the pressure and deformation relation of the major axis and the minor axis of the ellipse and calculate the main stress direction and the main stress magnitude according to the pressure data, the deformation data and the azimuth data.
According to the method, the drilling rock mass is deformed in an active pressurizing and pressure releasing mode, and the maximum main stress, the minimum main stress and the main stress direction of the drilling section are obtained by measuring drilling deformation data and test pressure and combining the deformation characteristics of the rock mass. The embodiment of the invention provides a measuring method for rapidly measuring the ground stress of a soft rock stratum, which comprises the following steps:
firstly, forming a measuring drilling hole 4 by drilling holes in key parts of engineering, wherein the hole diameter is matched with the diameter 3-1 of the telescopic capsule;
secondly, after hole forming is completed, selecting a determined hole depth, putting the determined hole depth into a telescopic capsule 3-1 and a signal bin 3-3, connecting the telescopic capsule 3-1 with a pressure pump 1-5 through a pressure pipeline 2-1, and arranging a pressure sensor 1-4 and a pressure gauge 1-3 on the pressure pipeline 2-1; the three-dimensional electronic compass, the signal processing circuit and the communication circuit are packaged in the signal bin (3-3), the signal bin (3-3) is connected with the signal line (2-2) through the signal line (2-2), the other end of the signal bin is communicated with the data acquisition instrument (1-2) and is connected with the data acquisition instrument (1-2) and the computer (1-1), the pressure sensor (1-4) is used for acquiring pressure data of the telescopic capsule (3-1), the ranging element (3-2) is used for detecting deformation data of a position of the ranging element of the telescopic capsule (3-1) in the pressurizing process, and the three-dimensional electronic compass is used for detecting azimuth data of an X axis of the telescopic capsule (3-1); thirdly, pumping a medium into the pressure pipeline 2-1 by the pressure pump 1-5 to enable the telescopic capsule 3-1 to expand and deform until the telescopic capsule is completely attached to the wall of the measuring borehole 4, and then carrying out a loading test according to a specific pressurizing mode, wherein in the process, pressure data, ranging signals and azimuth data are acquired and recorded in the whole process, and the data are transmitted to the computer 1-1 for storage, processing and display by the data acquisition instrument 1-2. Optionally, carrying out auxiliary tests such as a uniaxial loading test and the like on the collected drill core to obtain the relation between rock pressure loading and deformation, and the elastic modulus E and the Poisson ratio mu.
And fourthly, carrying out result calculation by test data, namely obtaining the main stress direction of the cross section of the drilling hole by ellipsometry simulation of deformation data of the drilling hole in the measuring process and azimuth data, wherein the main stress magnitude is determined by elastic deformation, elastic modulus, applied stress and the like in the major axis direction and the minor axis direction obtained in a special loading mode.
The single test of the invention can give out the two-dimensional ground stress result of the cross section of the drill hole, namely the main stress direction and the main stress magnitude of the cross section of the drill hole. The main stress direction of the cross section of the borehole is obtained by ellipsometry simulation of the deformation of the aperture during the borehole pressing. According to deformation data of the telescopic capsule 3-1, the deformation of the simulated drilling aperture can be calculated and ovalized in real time, the major axis direction of the oval shape is the minimum principal stress direction, the included angle between the major axis direction of the aperture deformation ovalization result and the direction of the X axis of the telescopic capsule 3-1 is alpha, the included angle between the X axis and the reference N of the three-dimensional electronic compass is beta, and when theta=alpha+beta, the angle of the maximum principal stress direction relative to the measurement reference N of the three-dimensional electronic compass is theta+/-90 degrees.
The invention provides a special loading mode for separating out the elastic deformation of soft rock, which is adjustable in order to obtain a high measurement accuracy result. A demonstration of the deformation of the capsule under pressure is shown in figure 3. The state 0 is the initial state that the measuring device is placed in the hole and is not pressurized, the state I is the initial state that the capsule is tightly attached to the hole wall, the state E is the equipment limit loading state, the limit pressure born by the equipment or the use limiting pressure is adopted, and a test interval is arranged between the state I and the state E. The loading mode provided by the invention is as follows: the capsule is continuously pressurized after being tightly adhered to the hole wall, the pressure p 1 is set as a starting point of the calculated pressure, for example, the pressure of the telescopic capsule when p 1＝(pI+1)MPa,pI is in an I state is set as C 1 state, the maximum value of the applied stress in the calculation loading process is set as p 2,p2, the maximum loading pressure of the equipment and the measurement condition of a measurer are determined, the injection medium of the telescopic capsule 3-1 is loaded to the pressure p 2, namely, the pressurizing pump is closed when the pressure is in a C 2 state, the medium is slowly released until the pressure is reduced to p 1, the state is set as C 3, the aperture deformation ellipses of the telescopic capsule in the long axis and the short axis directions are shown in figure 5 in the process.
The magnitude calculation of the invention is related to the loading mode and the value, under the loading mode of the example, the elastic deformation data can be separated by using the measurement process data, the principal stress magnitude of the cross section of the drill hole is calculated by the formula (1), the coordinate systems of the figures 3 and 4 and the measurement data shown in the figure 5 are adopted,
Wherein: σ 1 is the plane maximum principal stress, σ 2 is the plane minimum principal stress, u ae is elastic recovery deformation in the long axis direction of the states from C 2 to C 3, u be is elastic recovery deformation in the short axis direction, and the calculation formula is shown in formula (2) and is obtained from ovalization simulation data of aperture deformation in the states from C 2 to C 3;
Corresponding to the p-u curve shown in FIG. 5, u 2a and u 2b in formula (2) are the deformations of the C 3 state to the I state in the major axis direction and the minor axis direction, respectively; u a and u b are pore diameter deformations in the major and minor axis directions from the I state to the C 2 state, respectively.
Μ is the poisson ratio of the rock mass, which can be estimated or obtained by auxiliary tests;
r is the radius of the test drilling hole, and the drilling tool data can be obtained or adopted by the measurement data of the I state; the pressure difference between the state of p 1 and the state of C 2 is calculated by a formula (p 2-p1), the pressure of the telescopic capsule can be set when p 1＝(pI+1)MPa,pI is in the state of I, the state of I is the initial state of the capsule close to the hole wall, and p 2 is the maximum value of the stress applied in the calculation and loading process; e is the elastic modulus of the rock mass;
e is the elastic modulus of the rock mass, which can be obtained by the pressure and elastic deformation of the states of C 2 to C 3, and an example calculation method is shown in the formula (3),
(3) Wherein A is a coefficient related to the measuring device; u 2a and u 2b are the deformations of the C 3 state relative to the I state in the major and minor axis directions, respectively; u a and u b are deformations in the major and minor axis directions from the I state to the C 2 state, respectively.
The device and the calculation method can be used for rapidly measuring the ground stress of the soft rock, the magnitude and the direction of the two-dimensional main stress of the cross section of the drill hole can be obtained through single test, the sleeve drill hole releasing operation is not needed in the measuring process, the measuring time is saved by more than 50% compared with that of a hydraulic fracturing method and a pore diameter deformation method, and the three-dimensional stress result can be obtained through three-hole and more than intersection hole systems. The measuring step, the loading mode and the calculating method are application examples of the invention, and various loading modes and calculating methods are optional, so that the measurement accuracy can be checked and the method is optimized.
The foregoing is merely illustrative embodiments of the present invention, and the present invention is not limited thereto, and any changes or substitutions that may be easily contemplated by those skilled in the art within the scope of the present invention should be included in the scope of the present invention.
Claims (5)
1. The utility model provides a survey device of quick survey soft rock stratum crustal stress which characterized in that: the drilling machine comprises a pressurizing deformation subsystem and a data measurement subsystem, wherein the pressurizing deformation subsystem is used for carrying out full-section internal pressurization on a drilling hole in a special loading mode to enable an aperture to be expanded and deformed, the data measurement subsystem is used for collecting deformation data, azimuth data and pressure data of the pressurizing deformation subsystem in the aperture expansion deformation, determining a ground stress state by utilizing ground stress, applied stress and deformation characteristics of a rock mass, carrying out ovalization simulation of aperture deformation according to the deformation data, calculating pressure and deformation relations in a major axis direction and a minor axis direction of deformation by combining the pressure data and the azimuth data, determining a main stress direction and a main stress magnitude of a drilling hole cross section, wherein the main stress direction of the drilling hole cross section is obtained by ovalization simulation and azimuth data of the deformation data of the drilling hole in a measurement process, and the direction of the minimum deformation is the maximum main stress direction of the cross section; the main stress magnitude is determined by elastic recovery deformation, elastic modulus and applied stress in the major axis direction and the minor axis direction of the deformed ellipse obtained in a special loading mode;
The pressure applying deformation subsystem comprises a pressure pump (1-5), a pressure pipeline (2-1) and a telescopic capsule (3-1), wherein the telescopic capsule (3-1) is arranged in a measuring drilling hole (4) formed by pore-forming of an engineering key position, the pressure pump (1-5) is connected with the telescopic capsule (3-1) through the pressure pipeline (2-1), when the telescopic capsule (3-1) is filled with medium and is tightly adhered to a hole wall, the telescopic capsule (3-1) radially expands when the pressure pump (1-5) continuously pumps in pressure conduction medium, the aperture of the measuring drilling hole (4) is deformed, and the pressure pump (1-5) is closed to enable the medium to flow back, so that the telescopic capsule (3-1) is contracted;
The data measurement subsystem comprises a pressure sensor (1-4), a pressure gauge (1-3), a data acquisition instrument (1-2), a signal bin (3-3), a computer (1-1), a ranging element (3-2) circumferentially arranged in the telescopic capsule (3-1) and a three-dimensional electronic compass connected with the telescopic capsule (3-1), wherein the pressure sensor (1-4) is used for acquiring pressure data of the telescopic capsule (3-1), the ranging element (3-2) is used for detecting deformation data of a position of the telescopic capsule (3-1) where the ranging element is located in the pressurizing process, the three-dimensional electronic compass is used for detecting azimuth data beta of an X axis of the telescopic capsule (3-1), the ranging element (3-2) and the three-dimensional electronic compass are connected with the data acquisition instrument (1-2) through the signal bin (3-3), a signal output end of the data acquisition instrument (1-2) is connected with the computer (1-1), the signal bin (3-3) has data acquisition, processing and communication functions, the signal sensor is connected with a first signal receiving end (1-2) of the data acquisition instrument, and a second signal receiving end (1-4) of the data acquisition instrument is connected with the data acquisition instrument (1-2), the signal output end of the data acquisition instrument (1-2) is connected with the computer (1-1);
The main stress direction of the cross section of the drill hole is obtained by ellipsometry simulation and azimuth data of drill hole deformation data in the measuring process, the angle between the long axis direction and the X axis of the ellipsometry result of the aperture deformation is set to be alpha, and the maximum main stress direction of the cross section is perpendicular to the long axis direction and is known to be theta+/-90 degrees;
the special loading mode is a mode that pressurization and pressure release are in the same pressure interval, elastic deformation is separated, and main stress magnitude calculation is carried out;
The principal stress magnitude of the borehole cross section is calculated by equation (1):
Wherein: Is the maximum principal stress of the plane,/> For the minimum principal stress of the plane, u ae is elastic recovery deformation in the long axis direction of the state from C 2 to C 3, u be is elastic recovery deformation in the short axis direction, and the plane is obtained from elliptical simulation data of aperture deformation in the state from C 2 to C 3, and the calculation formula is shown in formula (2):
In the formula (2), u 2a and u 2b are respectively the deformation of the C 3 state to the I state in the long axis direction and the short axis direction; u a and u b are pore diameter deformations in the major and minor axis directions from the I state to the C 2 state, respectively;
μ is the poisson ratio of the rock mass, estimated or obtained from an auxiliary test; r is the radius of a test drilling hole, p is the pressure difference between the state of C 1 and the state of C 2, a calculation formula is (p 2-p1), the pressure of the telescopic capsule is set when p 1=（pI+1）MPa,pI is in the state of I, the state of I is the initial state of the capsule tightly attached to the hole wall, and p 2 is the maximum value of the stress applied in the process of setting and calculating; e is the elastic modulus of the rock mass.
2. The measurement device for quick determination of soft rock formation crustal stress according to claim 1, wherein: the three-dimensional electronic compass, the signal processing circuit and the communication circuit are packaged in the signal bin (3-3), the ranging element (3-2) and the three-dimensional electronic compass are connected with the signal processing circuit, the signal processing circuit is connected with the communication circuit, and the communication circuit is connected with a first signal receiving end of the data acquisition instrument (1-2) through the signal wire (2-2); the three-dimensional electronic compass is used for providing an included angle between the measurement reference N and the X axis of the telescopic capsule (3-1), namely azimuth data beta; the signal processing circuit transmits the azimuth data and the deformation data to the acquisition instrument (1-2) through the signal line (2-2) by the communication circuit.
3. The measurement device for quick determination of soft rock formation crustal stress according to claim 1, wherein: the elastic modulus E of the rock mass is obtained by the pressure change and elastic deformation of the states from C 2 to C 3 and is calculated by the formula (3):
；
Wherein A is a coefficient related to the measuring device; u 2a and u 2b are the deformations of the C 3 state relative to the I state in the major and minor axis directions, respectively; u a and u b are deformations in the major and minor axis directions from the I state to the C 2 state, respectively.
4. The measurement device for quick determination of soft rock formation crustal stress according to claim 1, wherein: the pressure-conducting medium is a gas or a liquid.
5. A method for measuring the ground stress of a fast determination soft rock stratum, characterized in that the method is carried out by using the device according to any one of claims 1-4, the method comprising the steps of:
Firstly, forming a measuring drilling hole (4) by drilling holes in key parts of engineering, wherein the hole diameter is matched with the diameter (3-1) of the telescopic capsule;
Step two, after hole forming is completed, connecting a pressure applying deformation pipeline and a data measuring pipeline, and selectively putting a telescopic capsule (3-1) and a signal bin (3-3) into a determined hole depth, wherein the telescopic capsule (3-1) is connected with a pressurizing pump (1-5) through a pressure pipeline (2-1), and a pressure sensor (1-4) and a pressure gauge (1-3) are arranged on the pressure pipeline (2-1); the three-dimensional electronic compass, the signal processing circuit and the communication circuit are packaged in the signal bin (3-3), the signal bin (3-3) is connected through a signal line (2-2) and a signal line (2-2), the other end of the signal bin is communicated with the data acquisition instrument (1-2) and is connected with the data acquisition instrument (1-2) and the computer (1-1), the pressure sensor (1-4) is used for acquiring pressure data of the telescopic capsule (3-1), the ranging element (3-2) is used for detecting deformation data of a position of the ranging element of the telescopic capsule (3-1) in the pressurizing process, and the three-dimensional electronic compass is used for detecting azimuth data beta of the X-axis direction of the telescopic capsule (3-1);
Pumping a medium into the pressure pipeline (2-1) by the pressure pump (1-5) to enable the telescopic capsule (3-1) to expand and deform until the telescopic capsule is completely attached to the wall of the measuring drill hole (4), then carrying out a loading test of a calculation process, acquiring and recording the pressure data, deformation data and azimuth data in the whole process, and transmitting the pressure data, the deformation data and the azimuth data to the computer (1-1) through the data acquisition instrument (1-2) for storage, processing and display;
and fourthly, carrying out result calculation by test data, namely, obtaining the main stress direction of the cross section of the drilling hole by ellipsometry simulation of deformation data and azimuth data of the drilling hole in the measuring process, wherein the main stress magnitude is determined by elastic recovery deformation, elastic modulus and applied stress in the long axis direction and the short axis direction which are obtained in a special loading mode.
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