Fractured rock mass crustal stress measurement method and device based on wave velocity and stress correlation

Abstract

The invention provides a fractured rock mass crustal stress measurement method and device based on wave velocity and stress correlation, and relates to the technical field of crustal stress measurement. The method comprises the following steps: acquiring rock mass wave velocity data of protolith under a crustal stress field in different drill hole directions; based on the relation between the wave velocity and the stress in the acoustic elasticity theory, unknown parameters in the wave velocity and stress relational expression of the fractured rock mass are reversely deduced, and the wave velocity and stress relational expression of the fractured rock mass is constructed; and calculating the crustal stress value in the x direction, the crustal stress value in the y direction and the crustal stress value in the z direction of the measurement area through a borehole stress state inversion method according to the rock mass wave velocity data of the original rock and the wave velocity and stress relational expression of the fractured rock mass. According to the invention, the crustal stress measurement precision based on the wave velocity can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ground stress measurement, and in particular to a method and device for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation. Background Art

[0002] In-situ stress is the natural stress present in the ground, undisturbed by engineering. It is the fundamental force causing deformation and failure in underground rock excavation projects. Measuring in-situ stress is the only way to understand the in-situ stress state of an area and is an essential prerequisite for conducting surrounding rock stability analysis, rock excavation design, and scientific decision-making. Decades of development have led to the development of hydraulic fracturing, acoustic emission, casing stress relief, and stress recovery methods. Stress relief and hydraulic fracturing are currently the most widely used methods for in-situ stress measurement. The core technology of the stress relief method involves drilling a large hole downhole, four to six times the width of the tunnel and with a diameter of 100 mm. A small hole is drilled at the bottom of the hole and pre-embedded with strain gauges. After drilling, the rock mass is freed from constraints, and the strain gauges record the strain changes. The initial in-situ stress state is then restored through theoretical calculations. This method offers high measurement accuracy, but it also requires a long measurement cycle and high drilling costs. Furthermore, the subsequent stress relief process requires sophisticated drilling techniques, is prone to equipment damage, and has a high failure rate. The basic principle of hydraulic fracturing is to apply pressure through high-pressure fluid in a borehole, causing cracks to expand in the rock mass. The pressure data generated by the cracks is measured and combined with rock mechanical parameters to calculate the magnitude of the in-situ stress. However, one direction of the in-situ stress tensor must be consistent with the direction of the borehole axis. Engineering is limited to in-situ stress measurement in a two-dimensional state, and the direction of the original rock stress cannot be identified. In addition, natural rock masses contain cracks and joints with a certain orientation and density. Existing in-situ stress measurement methods have high requirements for rock mass integrity, and the measurement accuracy is affected by the orientation and density of the rock mass cracks. Ultrasonic technology, as one of the modern detection technologies, is widely used in the fields of non-destructive testing, physical property measurement, and calibration measurement in industry and scientific research. Metal component stress measurement technology based on ultrasonic and elastic wave detection has gradually matured, but most of it is aimed at small metal components. However, there are few reports on rock mass stress measurement technology.

[0003] Patent document CN119469542A proposes the use of distributed probes on components to detect the stress state of workpieces through phased array signal transmission and reception, but it is only applicable to small metal components and cannot be used for in-situ rock stress detection; Patent document CN222028212U proposes a coal rock ultrasonic measurement method with adjustable prestress, but this method can only realize the stress state measurement of small rock specimens and cannot be used for engineering rock stress detection; Patent document CN105136362A proposes a measurement device and method for determining the direction of ground stress based on the anisotropy of rock wave velocity. The measurement device can control the rotating table to drive the core to rotate 360 degrees, the acoustic wave device to move up and down, and the pressure exerted by the acoustic wave device and the rock core by rotating different hand wheels, thereby accurately measuring the acoustic wave data at different heights in all directions of the rock core. Patent document CN105804731B proposes a rock in-situ stress detection method and system, which uses a distributed acoustic wave probe to measure the wave velocity in all directions of a cylindrical rock specimen, assuming that "the maximum compressive strength of the drilled rock sample is the maximum horizontal in-situ stress and the minimum horizontal in-situ stress of the rock", and calculates the in-situ stress through the wave velocity and propagation path; Patent document CN118937491A proposes a rock three-dimensional spatial stress direction measurement method and system, prepares a spherical core sample, and conducts a wave velocity anisotropy test, assuming that "the angle corresponding to the maximum wave velocity position is determined as the direction of the minimum horizontal principal stress relative to the core, and the angle corresponding to the minimum wave velocity position is determined as the direction of the minimum horizontal principal stress relative to the core. The angle corresponding to the medium wave velocity position is determined as the direction of the maximum horizontal principal stress relative to the core, and the angle corresponding to the medium wave velocity position is determined as the direction of the vertical stress relative to the core. The measurement objects of the above-mentioned devices and methods are all rock specimens, and the relevant measurements are limited to the laboratory. At the same time, each method proposes certain assumptions, and the measurement results are limited to calculations obtained under the assumptions. Like the stress relief method and hydraulic fracturing method, ground stress measurement is mainly based on in-situ measurement, supplemented by indoor test calibration, but there is still a lack of specific ground stress ultrasonic measurement methods. In summary, the current ground stress ultrasonic measurement is still in the initial exploratory stage, limited to the stress measurement of small indoor specimens, and lacks a detailed and specific engineering size rock ground stress ultrasonic velocity measurement method. Summary of the Invention

[0004] To address the technical issues of existing ultrasonic velocity measurement methods for rock mass in-situ stress, which are limited to stress measurement on small indoor specimens and lack detailed and specific engineering dimensions, the present invention provides a method and device for measuring in-situ stress in fractured rock masses based on the correlation between wave velocity and stress. The technical solution is as follows:

[0005] In one aspect, a method for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation is provided. The method is implemented by a fractured rock mass ground stress measuring device based on wave velocity and stress correlation. The method comprises:

[0006] S1. Obtaining wave velocity data of in-situ rock mass under the ground stress field of different drilling directions;

[0007] S2. Based on the relationship between wave velocity and stress in the acoustoelasticity theory, the unknown parameters in the relationship between wave velocity and stress of fractured rock mass are reversed to construct the relationship between wave velocity and stress of fractured rock mass;

[0008] S3. Calculate the in-situ stress values in the x-direction, the y-direction, and the z-direction in the measurement area based on the original rock mass velocity data and the relationship between the fractured rock mass velocity and stress by using a borehole stress state inversion method.

[0009] Optionally, before the step of obtaining the wave velocity data of the original rock mass under the ground stress field of different drilling directions in S1, the method further includes:

[0010] In three or more underground excavation spaces of different depths, vertical fan-shaped drilling and horizontal fan-shaped drilling of specific depths are carried out in the tunnels least disturbed by mining. The diameter of the drilling holes is 50 mm, and in-situ rock coring is carried out in the in-situ rock measurement area through the excavation of the stress disturbance zone.

[0011] Optionally, the specific depth refers to dividing the drilling depth into two parts according to the drilling position of the borehole, one part is from the tunnel section to more than 4 times the excavation diameter, recorded as D1 or above, and is the disturbance stress area recorded as D2; the other part is located at 4 to 7 times the excavation diameter, located in the original rock area, and is the measurement area recorded as D0.

[0012] Optionally, the vertical fan-shaped arrangement refers to drilling holes perpendicular to the direction of the tunnel, with the center of the tunnel section as the center of the circle, towards the top, bottom and horizontal of the tunnel, and drilling a hole every 15° between the horizontal and top holes with the center of the tunnel section as the center of the circle;

[0013] Among them, the horizontal fan-shaped arrangement refers to the arrangement of drilling holes in a vertical fan-shaped manner, in which the level of the horizontal drilling hole is the horizontal plane of the tunnel, the horizontal drilling hole is the initial drilling hole, the center of the tunnel section is the center of the circle, and a hole is drilled every 15° clockwise on the horizontal plane of the tunnel, and 3 to 4 holes are drilled.

[0014] Optionally, obtaining the original rock mass wave velocity data under the ground stress field of different drilling directions includes:

[0015] Ultrasonic in-situ rock velocity measurement is performed in the measurement area to obtain in-situ rock velocity data under the ground stress field of different borehole directions. The ultrasonic in-situ rock velocity measurement refers to the use of a three-transmitter and three-receiver linear array probe to measure a set of velocity data at intervals I1. The measurement interval I1 satisfies 10 I1= D3. D3 represents the effective length of the measurement area for velocity measurement.

[0016] Optionally, the relationship between the wave velocity and stress of the fractured rock mass is expressed by the following formula (1):

[0017] V P 2 =(V p0 ) 2 +Aσ+Bσcos 2 β(1)

[0018] Among them, V p0 It represents the wave velocity of rock material under stress-free load; A is the first-order derivative of the wave velocity with stress; B is the second-order derivative of the wave velocity with stress; σ represents the compressive stress; β represents the angle between the compressive stress direction and the axis of the specimen, which is generally taken as 0°.

[0019] On the other hand, a device for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation is provided. The device is applied to a method for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation. The device comprises:

[0020] An acquisition unit is used to obtain wave velocity data of the original rock mass under the ground stress field of different drilling directions;

[0021] A construction unit is used to reversely infer the unknown parameters in the wave velocity and stress relationship of fractured rock mass based on the relationship between wave velocity and stress in the acoustoelasticity theory, and to construct the wave velocity and stress relationship of fractured rock mass;

[0022] The calculation unit is used to calculate the ground stress value in the x direction, the ground stress value in the y direction and the ground stress value in the z direction of the measurement area according to the wave velocity data of the original rock mass and the relationship between the wave velocity and stress of the fractured rock mass through the borehole stress state inversion method.

[0023] Optionally, before the step of obtaining the wave velocity data of the original rock mass under the ground stress field of different drilling directions, the method further includes:

[0024] In three or more underground excavation spaces of different depths, vertical fan-shaped drilling and horizontal fan-shaped drilling of specific depths are carried out in the tunnels least disturbed by mining. The diameter of the drilling holes is 50 mm, and in-situ rock coring is carried out in the in-situ rock measurement area through the excavation of the stress disturbance zone.

[0025] Optionally, the specific depth refers to dividing the drilling depth into two parts according to the drilling position of the borehole, one part is from the tunnel section to more than 4 times the excavation diameter, recorded as D1 or above, and is the disturbance stress area recorded as D2; the other part is located at 4 to 7 times the excavation diameter, located in the original rock area, and is the measurement area recorded as D0.

[0026] Optionally, the vertical fan-shaped arrangement refers to drilling holes perpendicular to the direction of the tunnel, with the center of the tunnel section as the center of the circle, towards the top, bottom and horizontal of the tunnel, and drilling a hole every 15° between the horizontal and top holes with the center of the tunnel section as the center of the circle;

[0027] Among them, the horizontal fan-shaped arrangement refers to the arrangement of drilling holes in a vertical fan-shaped manner, in which the level of the horizontal drilling hole is the horizontal plane of the tunnel, the horizontal drilling hole is the initial drilling hole, the center of the tunnel section is the center of the circle, and a hole is drilled every 15° clockwise on the horizontal plane of the tunnel, and 3 to 4 holes are drilled.

[0028] Optionally, obtaining the original rock mass wave velocity data under the ground stress field of different drilling directions includes:

[0029] Ultrasonic in-situ rock velocity measurement is performed in the measurement area to obtain in-situ rock velocity data under the ground stress field of different borehole directions. The ultrasonic in-situ rock velocity measurement refers to the use of a three-transmitter and three-receiver linear array probe to measure a set of velocity data at intervals I1. The measurement interval I1 satisfies 10 I1= D3. D3 represents the effective length of the measurement area for velocity measurement.

[0030] Optionally, the relationship between the wave velocity and stress of the fractured rock mass is expressed by the following formula (1):

[0031] V P 2 =(V p0 ) 2 +Aσ+Bσcos 2 β(1)

[0032] Among them, V p0 It represents the wave velocity of rock material under stress-free load; A is the first-order derivative of the wave velocity with stress; B is the second-order derivative of the wave velocity with stress; σ represents the compressive stress; β represents the angle between the compressive stress direction and the axis of the specimen, which is generally taken as 0°.

[0033] On the other hand, a device for measuring ground stress in a fractured rock mass based on the correlation between wave velocity and stress is provided. The device for measuring ground stress in a fractured rock mass based on the correlation between wave velocity and stress comprises: a processor; and a memory, wherein computer-readable instructions are stored on the memory. When the computer-readable instructions are executed by the processor, any one of the above-mentioned methods for measuring ground stress in a fractured rock mass based on the correlation between wave velocity and stress is implemented.

[0034] On the other hand, a computer-readable storage medium is provided, in which at least one instruction is stored. The at least one instruction is loaded and executed by a processor to implement any of the above-mentioned methods for measuring ground stress in fractured rock mass based on wave velocity and stress correlation.

[0035] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0036] The embodiment of the present invention first obtains the wave velocity data of the original rock mass under the ground stress field of different drilling directions; secondly, based on the relationship between wave velocity and stress in the acoustic elasticity theory, the unknown parameters in the wave velocity and stress relationship of the fractured rock mass are reversed to construct the wave velocity and stress relationship of the fractured rock mass; finally, based on the wave velocity data of the original rock mass and the wave velocity and stress relationship of the fractured rock mass, the ground stress value in the x direction, the ground stress value in the y direction, and the ground stress value in the z direction of the measurement area are calculated through the borehole stress state inversion method.

[0037] The embodiment of the present invention can be performed in an underground excavation space and is suitable for in-situ geostress measurement of engineering rock masses. The wave velocity measurement borehole diameter is set to 50 mm, and the in-situ wave velocity measurement and subsequent calibration test are simple, easy to understand, and low-cost. The embodiment of the present invention combines the rock mass geostress measurement method calibrated by indoor wave velocity tests. Through fan-shaped drilling and wave velocity measurement, wave velocity-based stress inversion is directly performed on the original rock, and the measurement accuracy is higher than that of indoor tests. The wave velocity stress calibration also takes into account the distribution of fracture occurrence, reducing the influence of the direction and density of fracture joints on the measurement accuracy. The embodiment of the present invention is suitable for geostress measurement of all natural rock masses. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 This is a flow chart of a method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation provided by an embodiment of the present invention;

[0040] Figure 2 This is a structural diagram of a vertical fan-shaped drilling arrangement provided by an embodiment of the present invention;

[0041] Figure 3 This is a schematic structural diagram of a horizontal fan-shaped drilling arrangement provided by an embodiment of the present invention;

[0042] Figure 4 This is a schematic structural diagram of the arrangement of measurement points in an in-situ rock measurement area provided by an embodiment of the present invention;

[0043] Figure 5 This is a schematic structural diagram of a wave velocity measurement in an in-situ rock measurement area provided by an embodiment of the present invention;

[0044] Figure 6This is a block diagram of a device for measuring ground stress in fractured rock mass based on wave velocity and stress correlation provided by an embodiment of the present invention;

[0045] Figure 7 The diagram is a schematic structural diagram of a device for measuring ground stress in fractured rock mass based on the correlation between wave velocity and stress, provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0047] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as an "exemplary" in the present invention should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. Furthermore, in the embodiments of the present invention, "and / or" can mean both or either of the two.

[0048] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, when the distinction is not emphasized, the meanings they convey are the same. The terms "of," "corresponding," and "corresponding" may sometimes be used interchangeably. It should be noted that, when the distinction is not emphasized, the meanings they convey are the same.

[0049] In the embodiments of the present invention, sometimes a subscript such as W1 may be written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are the same.

[0050] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0051] The embodiment of the present invention provides a method for measuring ground stress in a fractured rock mass based on the correlation between wave velocity and stress. The method can be implemented by a device for measuring ground stress in a fractured rock mass based on the correlation between wave velocity and stress. The device for measuring ground stress in a fractured rock mass based on the correlation between wave velocity and stress can be a terminal or a server. Figure 1 The flowchart of the method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation is shown. The processing flow of the method may include the following steps:

[0052] S1. Obtain the wave velocity data of the original rock mass under the ground stress field of different drilling directions.

[0053] Optionally, before the step of obtaining the original rock mass wave velocity data under the ground stress field of different drilling directions in S1, the step further includes:

[0054] In three or more underground excavation spaces of different depths, vertical fan-shaped drilling and horizontal fan-shaped drilling of specific depths are carried out in the tunnels least disturbed by mining. The diameter of the drilling holes is 50 mm, and in-situ rock coring is carried out in the in-situ rock measurement area through the excavation of the stress disturbance zone.

[0055] Among them, in-situ coring means that the coring position during drilling is within the measurement area, and the advancement speed is reduced as much as possible during drilling to ensure the integrity of the core.

[0056] Optionally, the specific depth refers to dividing the borehole depth into two parts according to the drilling position of the borehole, one part is from the tunnel section to more than 4 times the excavation diameter, recorded as above D1, and is the disturbance stress area recorded as D2; the other part is located at 4 to 7 times the excavation diameter, located in the original rock area, and is the measurement area recorded as D0.

[0057] Among them, the distance between the disturbance stress zone and the center of the tunnel is D2; the distance between the measurement area and the center of the tunnel is D3; the requirements for each area are 4D1<D2, 5D1<D0<7D1, and the depth of all boreholes reaches or exceeds the measurement area; D1 represents the excavation diameter; D0 represents the length of the original rock stress zone.

[0058] Among them, Figure 2 The figure shows a structural schematic diagram of a vertical fan-shaped drilling arrangement provided by an embodiment of the present invention; wherein 1 is a tunnel, 2 is a borehole, 3 is a stress disturbance area, and 4 is an in-situ rock measurement area.

[0059] Optionally, the vertical fan-shaped arrangement refers to drilling holes perpendicular to the direction of the tunnel, with the center of the tunnel section as the center of the circle, towards the top, bottom and horizontal of the tunnel, and drilling a hole every 15° between the horizontal and top holes with the center of the tunnel section as the center of the circle;

[0060] Among them, according to the vertical fan-shaped drilling method, drilling at a specified angle can be further performed between the horizontal drilling and the bottom drilling, thereby increasing the experimental amount of measurement data.

[0061] Among them, Figure 3 The figure shows a schematic diagram of a horizontal fan-shaped drilling arrangement according to an embodiment of the present invention; 1 represents a roadway, 2 represents a borehole, 3 represents a stress disturbance zone, and 4 represents an in-situ rock measurement zone. A horizontal fan-shaped arrangement refers to a vertical fan-shaped arrangement of drill holes, where the horizontal drill hole is located at the roadway level, the horizontal drill hole is the initial drill hole, and 3 to 4 holes are drilled clockwise every 15° in the roadway level, with the center of the roadway cross section as the center of the circle.

[0062] Among them, according to the drilling method of horizontal fan-shaped arrangement, drilling at a specified angle can be further performed counterclockwise to increase the experimental amount of measurement data.

[0063] Optionally, obtain the original rock mass wave velocity data under the ground stress field of different drilling directions, including:

[0064] Ultrasonic in-situ rock velocity measurement is performed in the measurement area to obtain in-situ rock velocity data under the ground stress field of different borehole directions. The ultrasonic in-situ rock velocity measurement refers to the use of a three-transmitter and three-receiver linear array probe to measure a set of velocity data at every distance I1. The measurement interval I1 satisfies 10I1= D3. D3 represents the effective length of the measurement area for velocity measurement.

[0065] Among them, Figure 4 The figure shows a schematic structural diagram of the arrangement of measurement points in an in-situ rock measurement area provided by an embodiment of the present invention; wherein 2 is a borehole and 5 is a measurement point.

[0066] Among them, Figure 5 The figure shows a structural schematic diagram of wave velocity measurement in an in-situ rock measurement area provided by an embodiment of the present invention; wherein 2 is a borehole, 3 is a stress disturbance area, 4 is an in-situ rock measurement area, 5 is a measurement point, 6 is a push rod, 7 is a probe, and 8 is a connecting line.

[0067] Among them, the linear array probe consists of a push rod, a Shange transceiver-in-one drilling probe and a connecting line; among them, the three probes are linearly arranged on the top of the push rod, the distance between probe No. 1 and probe No. 2 is L1, and the distance between probe No. 2 and probe No. 3 is L2.

[0068] Among them, the ultrasonic probe is driven by a conventional velocimeter to receive and save signals, and the sound wave data is identified by wave velocity acquisition equipment to identify parameters such as wave velocity and amplitude.

[0069] S2. Based on the relationship between wave velocity and stress in the acoustoelasticity theory, the unknown parameters in the relationship between wave velocity and stress of fractured rock mass are inferred, and the relationship between wave velocity and stress of fractured rock mass is constructed.

[0070] In a feasible implementation method, the occurrence of core joints is identified based on a borehole television probe, the inclination, strike and crack aperture characteristics of the full-length joints are determined by wave velocity measurement, axial compression tests are carried out based on fractured core sampling, the wave velocity characteristics of different stress loading levels are determined, and the stress-wave velocity relationship curve is calibrated. Through wave velocity stress tests on cores under different loads, based on the relationship between wave velocity and stress in the acoustic elasticity theory and according to a large number of core test results, the unknown parameters in the wave velocity and stress relationship of the fractured rock mass are inferred, and the wave velocity and stress relationship of the fractured rock mass is constructed.

[0071] Among them, the calibration of the stress-wave velocity relationship of fractured rock cores refers to testing the core wave velocity under different stress conditions, establishing the relationship between joint occurrence, stress and wave velocity according to the joint direction; and inferring the unknown parameters in the relationship between wave velocity and stress of fractured rock mass based on the wave velocity and stress test data.

[0072] S3. Based on the wave velocity data of the original rock mass and the relationship between the wave velocity and stress of the fractured rock mass, the ground stress values in the x direction, the ground stress values in the y direction, and the ground stress values in the z direction of the measurement area are calculated by the borehole stress state inversion method.

[0073] In a feasible implementation manner, the borehole stress state inversion method is a technology that infers the ground stress distribution by analyzing the deformation or other relevant data around the borehole. This is a method mastered by those skilled in the art and will not be further elaborated in this embodiment of the present invention.

[0074] Alternatively, the relationship between wave velocity and stress in fractured rock mass can be expressed by the following formula (1):

[0075] V P 2 =(V p0 ) 2 +Aσ+Bσcos 2 β(1)

[0076] Among them, V p0 It represents the wave velocity of rock material under stress-free load; A is the first-order derivative of the wave velocity with stress; B is the second-order derivative of the wave velocity with stress; σ represents the compressive stress; β represents the angle between the compressive stress direction and the axis of the specimen, which is generally taken as 0°.

[0077] The embodiment of the present invention first obtains the wave velocity data of the original rock mass under the ground stress field of different drilling directions; secondly, based on the relationship between wave velocity and stress in the acoustic elasticity theory, the unknown parameters in the wave velocity and stress relationship of the fractured rock mass are reversed to construct the wave velocity and stress relationship of the fractured rock mass; finally, based on the wave velocity data of the original rock mass and the wave velocity and stress relationship of the fractured rock mass, the ground stress value in the x direction, the ground stress value in the y direction, and the ground stress value in the z direction of the measurement area are calculated through the borehole stress state inversion method.

[0078] The embodiment of the present invention can be performed in an underground excavation space and is suitable for in-situ geostress measurement of engineering rock masses. The wave velocity measurement borehole diameter is set to 50 mm, and the in-situ wave velocity measurement and subsequent calibration test are simple, easy to understand, and low-cost. The embodiment of the present invention combines the rock mass geostress measurement method calibrated by indoor wave velocity tests. Through fan-shaped drilling and wave velocity measurement, wave velocity-based stress inversion is directly performed on the original rock, and the measurement accuracy is higher than that of indoor tests. The wave velocity stress calibration also takes into account the distribution of fracture occurrence, reducing the influence of the direction and density of fracture joints on the measurement accuracy. The embodiment of the present invention is suitable for geostress measurement of all natural rock masses.

[0079] Figure 6This is a block diagram of a device for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation according to an exemplary embodiment. The device is used in a method for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation. Figure 6 The device includes an acquisition unit 610, a construction unit 620, and a calculation unit 630.

[0080] An acquisition unit 610 is used to acquire wave velocity data of the original rock mass under the ground stress field of different drilling directions;

[0081] A construction unit 620 is used to reversely infer unknown parameters in the wave velocity and stress relationship of the fractured rock mass based on the relationship between wave velocity and stress in the acoustoelasticity theory, and to construct the wave velocity and stress relationship of the fractured rock mass;

[0082] The calculation unit 630 is used to calculate the ground stress value in the x direction, the ground stress value in the y direction, and the ground stress value in the z direction of the measurement area based on the original rock mass wave velocity data and the relationship between the wave velocity and stress of the fractured rock mass through the borehole stress state inversion method.

[0083] Optionally, before the step of obtaining the wave velocity data of the original rock mass under the ground stress field of different drilling directions, the method further includes:

[0084] In three or more underground excavation spaces of different depths, vertical fan-shaped drilling and horizontal fan-shaped drilling of specific depths are carried out in the tunnels least disturbed by mining. The diameter of the drilling holes is 50 mm, and in-situ rock coring is carried out in the in-situ rock measurement area through the excavation of the stress disturbance zone.

[0085] Optionally, the specific depth refers to dividing the drilling depth into two parts according to the drilling position of the borehole, one part is from the tunnel section to more than 4 times the excavation diameter, recorded as D1 or above, and is the disturbance stress area recorded as D2; the other part is located at 4 to 7 times the excavation diameter, located in the original rock area, and is the measurement area recorded as D0.

[0086] Optionally, the vertical fan-shaped arrangement refers to drilling holes perpendicular to the direction of the tunnel, with the center of the tunnel section as the center of the circle, towards the top, bottom and horizontal of the tunnel, and drilling a hole every 15° between the horizontal and top holes with the center of the tunnel section as the center of the circle;

[0087] Among them, the horizontal fan-shaped arrangement refers to the arrangement of drilling holes in a vertical fan-shaped manner, in which the level of the horizontal drilling hole is the horizontal plane of the tunnel, the horizontal drilling hole is the initial drilling hole, the center of the tunnel section is the center of the circle, and a hole is drilled every 15° clockwise on the horizontal plane of the tunnel, and 3 to 4 holes are drilled.

[0088] Optionally, obtaining the original rock mass wave velocity data under the ground stress field of different drilling directions includes:

[0089] Ultrasonic in-situ rock velocity measurement is performed in the measurement area to obtain in-situ rock velocity data under the ground stress field of different borehole directions. The ultrasonic in-situ rock velocity measurement refers to the use of a three-transmitter and three-receiver linear array probe to measure a set of velocity data at intervals I1. The measurement interval I1 satisfies 10 I1= D3. D3 represents the effective length of the measurement area for velocity measurement.

[0090] Optionally, the relationship between the wave velocity and stress of the fractured rock mass is expressed by the following formula (1):

[0091] V P 2 =(V p0 ) 2 +Aσ+Bσcos 2 β(1)

[0092] Among them, V p0 It represents the wave velocity of rock material under stress-free load; A is the first-order derivative of the wave velocity with stress; B is the second-order derivative of the wave velocity with stress; σ represents the compressive stress; β represents the angle between the compressive stress direction and the axis of the specimen, which is generally taken as 0°.

[0093] The embodiment of the present invention first obtains the wave velocity data of the original rock mass under the ground stress field of different drilling directions; secondly, based on the relationship between wave velocity and stress in the acoustic elasticity theory, the unknown parameters in the wave velocity and stress relationship of the fractured rock mass are reversed to construct the wave velocity and stress relationship of the fractured rock mass; finally, based on the wave velocity data of the original rock mass and the wave velocity and stress relationship of the fractured rock mass, the ground stress value in the x direction, the ground stress value in the y direction, and the ground stress value in the z direction of the measurement area are calculated through the borehole stress state inversion method.

[0094] The embodiment of the present invention can be performed in an underground excavation space and is suitable for in-situ geostress measurement of engineering rock masses. The wave velocity measurement borehole diameter is set to 50 mm, and the in-situ wave velocity measurement and subsequent calibration test are simple, easy to understand, and low-cost. The embodiment of the present invention combines the rock mass geostress measurement method calibrated by indoor wave velocity tests. Through fan-shaped drilling and wave velocity measurement, wave velocity-based stress inversion is directly performed on the original rock, and the measurement accuracy is higher than that of indoor tests. The wave velocity stress calibration also takes into account the distribution of fracture occurrence, reducing the influence of the direction and density of fracture joints on the measurement accuracy. The embodiment of the present invention is suitable for geostress measurement of all natural rock masses.

[0095] Figure 7 FIG. 1 is a schematic diagram of a structural diagram of a fractured rock mass stress measurement device based on wave velocity and stress correlation provided by an embodiment of the present invention. Figure 7 As shown, the fractured rock mass stress measurement equipment based on the wave velocity and stress correlation may include the above Figure 6The device for measuring ground stress in fractured rock mass based on the correlation between wave velocity and stress is shown. Optionally, the device for measuring ground stress in fractured rock mass based on the correlation between wave velocity and stress 710 may include a first processor 2001 .

[0096] Optionally, the fractured rock mass in-situ stress measurement device 710 based on wave velocity and stress correlation may further include a memory 2002 and a transceiver 2003 .

[0097] The first processor 2001, the memory 2002 and the transceiver 2003 may be connected via a communication bus.

[0098] The following combination Figure 7 The components of the fractured rock mass in-situ stress measurement device 710 based on wave velocity and stress correlation are described in detail:

[0099] The first processor 2001 is the control center of the fractured rock mass in-situ stress measurement device 710 based on wave velocity and stress correlation, and can be a single processor or a collective term for multiple processing elements. For example, the first processor 2001 can be one or more central processing units (CPUs), or application-specific integrated circuits (ASICs), or one or more integrated circuits configured to implement embodiments of the present invention, such as one or more digital signal processors (DSPs) or one or more field programmable gate arrays (FPGAs).

[0100] Optionally, the first processor 2001 may execute various functions of the fractured rock mass in-situ stress measurement device 710 based on wave velocity and stress correlation by running or executing a software program stored in the memory 2002 and calling data stored in the memory 2002 .

[0101] In a specific implementation, as an embodiment, the first processor 2001 may include one or more CPUs, such as Figure 7 CPU0 and CPU1 are shown in FIG.

[0102] In a specific implementation, as an embodiment, the fractured rock mass ground stress measurement device 710 based on wave velocity and stress correlation may also include multiple processors, such as Figure 71 and 2. The first processor 2001 and the second processor 2004 are shown in FIG. Each of these processors can be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). A processor herein can refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0103] The memory 2002 is used to store the software program for executing the solution of the present invention, and is controlled by the first processor 2001 for execution. The specific implementation method can refer to the above method embodiment and will not be repeated here.

[0104] Alternatively, the memory 2002 may be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, a random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, an optical disc storage (including a compact disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and capable of being accessed by a computer, but not limited thereto. The memory 2002 may be integrated with the first processor 2001 or exist independently and access the first processor 2001 through the interface circuit ( Figure 7 (not shown) is coupled to the first processor 2001, which is not specifically limited in this embodiment of the present invention.

[0105] The transceiver 2003 is used to communicate with a network device or a terminal device.

[0106] Optionally, the transceiver 2003 may include a receiver and a transmitter ( Figure 7 The receiver is used to implement a receiving function, and the transmitter is used to implement a sending function.

[0107] Optionally, the transceiver 2003 may be integrated with the first processor 2001 or may exist independently and be connected to the first processor 2001 through the interface circuit ( Figure 7(not shown) is coupled to the first processor 2001, which is not specifically limited in this embodiment of the present invention.

[0108] It should be noted that Figure 7 The structure of the fractured rock mass ground stress measurement device 710 based on wave velocity and stress correlation shown in the figure does not constitute a limitation on the router. The actual knowledge structure identification device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0109] In addition, the technical effects of the fractured rock mass ground stress measurement device 710 based on wave velocity and stress correlation can refer to the technical effects of the fractured rock mass ground stress measurement method based on wave velocity and stress correlation described in the above method embodiment, and will not be repeated here.

[0110] It should be understood that the first processor 2001 in the embodiment of the present invention may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc.

[0111] It should also be understood that the memory in the embodiments of the present invention may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory may be random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0112] The above embodiments can be implemented in whole or in part via software, hardware (e.g., circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product comprises one or more computer instructions or computer programs. When loaded or executed on a computer, the processes or functions described in accordance with the embodiments of the present invention are fully or partially performed. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired means (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium accessible by a computer or a data storage device such as a server or data center that contains a collection of one or more available media. The available medium can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media. The semiconductor media can be a solid-state drive.

[0113] It should be understood that the term "and / or" as used herein simply describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. A and B can be singular or plural. Furthermore, the character " / " as used herein generally indicates an "or" relationship between the associated objects, but it may also indicate an "and / or" relationship. For specific understanding, please refer to the context.

[0114] In this disclosure, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or plural.

[0115] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0116] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0117] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment, devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0118] In the several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of the device or unit, which can be electrical, mechanical or other forms.

[0119] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0120] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0121] If the functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or the portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage media include various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical disks.

[0122] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for measuring ground stress in fractured rock mass based on the correlation between wave velocity and stress, characterized in that: The method comprises: S1. Obtaining wave velocity data of in-situ rock mass under the ground stress field of different drilling directions; S2. Based on the relationship between wave velocity and stress in the acoustoelasticity theory, the unknown parameters in the relationship between wave velocity and stress of fractured rock mass are reversed to construct the relationship between wave velocity and stress of fractured rock mass; S3. Calculate the in-situ stress values in the x-direction, the y-direction, and the z-direction in the measurement area based on the original rock mass velocity data and the relationship between the fractured rock mass velocity and stress by using a borehole stress state inversion method.

2. The method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation according to claim 1, characterized in that: Before the step of obtaining the wave velocity data of the original rock mass under the ground stress field of different drilling directions in S1, the method further includes: In three or more underground excavation spaces of different depths, vertical fan-shaped drilling and horizontal fan-shaped drilling of specific depths are carried out in the tunnels least disturbed by mining. The diameter of the drilling holes is 50 mm, and in-situ rock coring is carried out in the in-situ rock measurement area through the excavation of the stress disturbance zone.

3. The method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation according to claim 2, characterized in that: The specific depth refers to dividing the drilling depth into two parts according to the drilling position of the borehole, one part is from the tunnel section to more than 4 times the excavation diameter, recorded as D1 or above, and is the disturbance stress area recorded as D2; the other part is located at 4 to 7 times the excavation diameter, located in the original rock area, and is the measurement area recorded as D0.

4. The method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation according to claim 2, characterized in that: The vertical fan-shaped arrangement refers to drilling holes perpendicular to the direction of the tunnel, with the center of the tunnel section as the center of the circle, towards the top, bottom and horizontal of the tunnel, and drilling a hole every 15° between the horizontal and top holes with the center of the tunnel section as the center of the circle; Among them, the horizontal fan-shaped arrangement refers to the arrangement of drilling holes in a vertical fan-shaped manner, in which the level of the horizontal drilling hole is the horizontal plane of the tunnel, the horizontal drilling hole is the initial drilling hole, the center of the tunnel section is the center of the circle, and a hole is drilled every 15° clockwise on the horizontal plane of the tunnel, and 3 to 4 holes are drilled.

5. The method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation according to claim 1, characterized in that: The method of obtaining the original rock mass wave velocity data under the in-situ stress field of different borehole directions includes: In the measurement area, ultrasonic in-situ measurement of rock velocity is carried out to obtain the original rock velocity data under the ground stress field of different borehole directions; wherein, ultrasonic in-situ measurement of rock velocity refers to the use of three-transmitter and three-receiver linear array probes, with each distance Measure a set of wave velocity data; among them, the measurement spacing satisfy ; Wherein, D3 represents the effective length of the wave velocity measurement in the measurement area.

6. The method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation according to claim 1, characterized in that: The relationship between the wave velocity and stress of the fractured rock mass is expressed by the following formula (1): V P 2 =(V p0 ) 2 +Aσ+Vσcos 2 b(1) in, represents the wave velocity of rock material under no stress load; A is the first-order derivative of the wave velocity with stress; B is the second-order derivative of the wave velocity with stress; σ represents the compressive stress; It represents the angle between the compressive stress direction and the axis of the specimen, and is generally taken as 0°.

7. A device for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation, wherein the device is used to implement the method for measuring ground stress in a fractured rock mass based on wave velocity and stress correlation as claimed in any one of claims 1 to 6, and is characterized in that: The device comprises: An acquisition unit is used to obtain wave velocity data of the original rock mass under the ground stress field of different drilling directions; A construction unit is used to reversely infer the unknown parameters in the wave velocity and stress relationship of fractured rock mass based on the relationship between wave velocity and stress in the acoustoelasticity theory, and to construct the wave velocity and stress relationship of fractured rock mass; The calculation unit is used to calculate the ground stress value in the x direction, the ground stress value in the y direction and the ground stress value in the z direction of the measurement area according to the wave velocity data of the original rock mass and the relationship between the wave velocity and stress of the fractured rock mass through the borehole stress state inversion method.

8. The method for measuring ground stress in fractured rock mass based on wave velocity and stress correlation according to claim 7, characterized in that: Before the step of obtaining the original rock mass wave velocity data under the ground stress field of different drilling directions, the method further includes: In three or more underground excavation spaces of different depths, vertical fan-shaped drilling and horizontal fan-shaped drilling of specific depths are carried out in the tunnels least disturbed by mining. The diameter of the drilling holes is 50 mm, and in-situ rock coring is carried out in the in-situ rock measurement area through the excavation of the stress disturbance zone.

9. A device for measuring ground stress in fractured rock mass based on the correlation between wave velocity and stress, characterized in that: The fractured rock mass ground stress measurement device based on wave velocity and stress correlation includes: processor; A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the method according to any one of claims 1 to 6 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program code, which can be called by a processor to execute the method according to any one of claims 1 to 6.

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