While-drilling ground stress testing device and method

Abstract

The invention relates to the technical field of stress testing, in particular to a while-drilling ground stress testing device and method.The while-drilling ground stress testing device comprises an outer-layer sleeve rod and an inner-layer sleeve rod coaxially arranged on the inner side of the outer-layer sleeve rod in a sleeving mode, and a plurality of inclined grooves are formed in the outer wall of the inner-layer sleeve rod in the axial direction at equal intervals; stress measuring points are arranged in the inclined grooves, and openings are formed in the positions, corresponding to the inclined grooves, of the outer wall of the outer-layer loop bar. Through relative axial movement of the inner-layer loop bar and the outer-layer loop bar, a stress measuring point can be safely contained in the outer-layer loop bar, and damage caused by friction and collision between the measuring point and a hole wall in the advancing process of a drill rod is effectively avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of stress testing, and in particular to a device and method for testing ground stress while drilling. Background Art

[0002] Engineering projects involving geotechnical materials typically involve excavation. Therefore, a stability analysis of the geotechnical materials is necessary before excavation begins to ensure construction safety. The distribution of initial geostress is a key factor in rock mass engineering design and stability analysis. Therefore, geostress testing of the geotechnical areas to be excavated is essential before construction officially begins.

[0003] At present, the distribution of geostress in rock and soil is mainly obtained by two technologies: hydraulic fracturing and stress relief. However, the measurement devices required by these two technologies are complex to operate, costly, and difficult to implement. Therefore, there is an urgent need to develop a geostress testing device that is easy to operate and low in cost. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a device and method for testing ground stress while drilling.

[0005] The present invention adopts the following technical solution: a stress-while-drilling testing device, comprising an outer sleeve and an inner sleeve coaxially sleeved inside the outer sleeve, wherein the inner sleeve can move axially along the length direction of the outer sleeve;

[0006] The outer wall of the inner sleeve is provided with a plurality of inclined grooves at equal intervals along the axial direction, each inclined groove is provided with a stress measuring point, and the outer wall of the outer sleeve is provided with openings at positions corresponding to the inclined grooves;

[0007] When the inner sleeve rod is driven to move axially within the outer sleeve rod, the stress measuring point can be synchronously driven to extend outward through the opening for stress monitoring. When the stress measuring point moves outward along the inclined groove on the surface of the inner sleeve rod, the edge of the opening on the outer sleeve rod constrains it, so that the stress measuring point finally extending from the opening can face the rock wall surface.

[0008] As a further description of the above technical solution: the inner sleeve rod is a tubular structure with a strip hole provided at the center, and a wire is arranged in the strip hole.

[0009] As a further description of the above technical solution: the stress measuring point is composed of a stress sensor, a connecting rod and a hook. The stress sensor is arranged in the inclined slide groove, and a bevel is preset on the side opposite to the inclined slide groove, so that the stress sensor and the side opposite to the inclined slide groove fit each other.

[0010] As a further description of the above technical solution: one end of the connecting rod is fixed on the outer wall of the stress sensor, the other end of the connecting rod passes through the inner sleeve rod and extends into the strip hole, and the outer sleeve rod is provided with an inclined sliding groove for use with the connecting rod.

[0011] As a further description of the above technical solution: a drill bit connecting device is fixed to one end of the outer sleeve along the length direction.

[0012] As a further description of the above technical solution: nuts are fixed on the outer wall of the outer sleeve rod and the inner wall of the inner sleeve rod, and bolts are threadedly connected between the two nuts to achieve relative fixation of the outer sleeve rod and the inner sleeve rod by the bolts and nuts.

[0013] A method for testing ground stress while drilling is implemented based on the above-mentioned ground stress testing device, comprising the following steps:

[0014] S1: When conducting a geostress test, the drill bit is connected to the geostress test device through the drill bit connection device. The drill bit is used to drill a hole in soft rock. The geostress test device is continuously advanced in the hole along with the drill bit in the drill pipe. At this time, the inner and outer casing rods remain relatively stationary, so that the stress measuring point is at the bottom position of the inclined groove on the surface of the inner casing rod. The outer casing rod can better protect the stress measuring point during the drilling process of the drill bit.

[0015] S2: When the drill bit reaches the specified depth and the in-situ stress test device reaches the predetermined in-situ stress test position, the in-situ stress test begins. The inner casing rod is pushed forward inside the outer casing rod. At this time, the stress measuring point moves outward along the inclined groove on the surface of the inner casing rod. The opening on the outer casing rod constrains the stress sensor, so that the contact surface between the stress sensor and the rock mass always remains parallel to the rock wall surface.

[0016] S3: When the inner rod is advanced to the stress measuring point and is in full contact with the rock mass, the advancement is stopped, the outer rod and the inner rod are fixed, the ground stress is tested through the stress measuring point, and the stress measuring point is connected to the data acquisition instrument through a wire to collect the ground stress data of the soft rock;

[0017] S4: After the test is completed, release the fixing of the sleeve rod, pull the inner sleeve rod back to the initial state, and retract the stress measuring point to the bottom position of the inclined groove on the surface of the inner sleeve rod to avoid damage to the stress measuring point during the process of pulling the device out of the borehole.

[0018] Beneficial effects:

[0019] The present invention provides a device for testing in-situ stress while drilling. The device can safely house a stress measuring point inside the outer casing rod through relative axial movement of inner and outer casing rods. This effectively prevents the measuring point from being damaged by friction and collision with the hole wall during the advancement of the drill rod. When the drill rod reaches a predetermined depth in the borehole, the inner casing rod is driven to move, allowing the stress measuring point to be precisely extended through the opening to the testing position. Once the device reaches the predetermined position, the stress measuring point can be directly extended and contact the surface of the soft rock hole wall, enabling direct, real-time measurement of in-situ in-situ stress. This avoids the core disturbance or installation delays that may be associated with traditional methods.

[0020] Furthermore, the in-situ stress testing device is particularly suitable for soft rock environments. By arranging multiple stress measuring points along the axial direction, continuous or selected point measurements can be performed at different depths during a single drilling process, effectively obtaining the in-situ stress distribution on the axial section of the soft rock borehole. The extension and retraction of the measuring points can be completed by utilizing the movement of the drill rod itself, without the need for additional complex operations or auxiliary tools, significantly improving the testing efficiency and convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further explained below in conjunction with the accompanying drawings and examples:

[0022] Figure 1 A schematic cross-sectional view of a device for testing ground stress while drilling provided in Example 1 of the present invention;

[0023] Figure 2 Provided in Example 1 of the present invention Figure 1 A magnified view of area A in ;

[0024] Figure 3 This is a flow chart of a method for testing ground stress while drilling provided in Example 2 of the present invention.

[0025] Figure numerals: 1. bolt; 2. nut; 3. outer sleeve; 31. opening; 32. strip hole; 4. inner sleeve; 41. inclined groove; 5. wire; 6. stress measuring point; 7. hook; 8. drill bit connecting device; 9. stress sensor; 10. connecting rod; 11. inclined slide. DETAILED DESCRIPTION

[0026] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific diagrams. It should be noted that the embodiments and features in the embodiments of this application can be combined with each other unless they conflict.

[0027] Example 1

[0028] See also Figure 1-Figure 2The embodiment of the present invention provides a technical solution: a device for testing ground stress while drilling, comprising an outer sleeve rod 3 and an inner sleeve rod 4 coaxially sleeved inside the outer sleeve rod 3, wherein the inner sleeve rod 4 can move axially along the length direction of the outer sleeve rod 3;

[0029] It should be noted that the outer sleeve 3 needs to be in direct contact with the rock wall, so it is made of hard materials such as steel pipes to prevent the outer sleeve 3 from rubbing against the rock wall during the drilling process and causing deformation, which may damage the stress measuring point 6.

[0030] The outer wall of the inner sleeve rod 4 is provided with a plurality of inclined grooves 41 at equal intervals in the axial direction. A stress measuring point 6 is provided in each inclined groove 41. The outer wall of the outer sleeve rod 3 is provided with openings 31 at positions corresponding to the inclined grooves 41.

[0031] When the inner sleeve rod 4 is driven to move axially within the outer sleeve rod 3, the stress measuring point 6 can be synchronously driven to extend outward through the opening 31 for stress monitoring. When the stress measuring point 6 moves outward along the inclined groove 41 on the surface of the inner sleeve rod 4, the edge of the opening 31 on the outer sleeve rod 3 constrains it, so that the stress measuring point 6 finally extending from the opening 31 can face the rock wall surface.

[0032] It should be noted that the driving mechanism that drives the inner sleeve rod 4 to move axially within the outer sleeve rod 3 is an electric telescopic rod or a hydraulic telescopic rod. The electric telescopic rod or the hydraulic telescopic rod is fixedly mounted on the inner wall of the outer sleeve rod 3, and its movable end is connected to the outer wall of one end of the inner sleeve rod 4. When in use, the electric telescopic rod or the hydraulic telescopic rod is controlled to extend and retract to drive the inner sleeve rod 4 to move axially within the outer sleeve rod 3.

[0033] The inner sleeve rod 4 is a tubular structure with a strip hole 32 provided at the center. A conductor 5 is arranged in the strip hole 32 .

[0034] Specifically, the ground stress is tested through the stress measuring point 6, and the stress measuring point 6 is connected to a data acquisition instrument through a wire 5, so as to collect the measured ground stress data.

[0035] The stress measuring point 6 consists of a stress sensor 9, a connecting rod 10 and a hook 7. The stress sensor 9 is arranged in an inclined chute 11, and a bevel is preset on the side opposite to the inclined chute 11, so that the stress sensor 9 and the side opposite to the inclined chute 11 fit together.

[0036] One end of the connecting rod 10 is fixed to the outer wall of the stress sensor 9 , and the other end of the connecting rod 10 passes through the inner sleeve rod 4 and extends into the strip hole 32 . The outer sleeve rod 3 is provided with an inclined slot 11 used to cooperate with the connecting rod 10 .

[0037] Specifically, through the inner opening of the inclined slide 11, the stress sensor 9 is connected to the hook 7 through the connecting rod 10, so that the stress measuring point 6 is always fixed inside the inclined slide 11, preventing the stress sensor 9 from falling off from the inclined groove 41. The wire 5 also passes through the hole into the hollow part in the middle of the inner sleeve rod 4 and is connected to the data acquisition instrument outside the device.

[0038] A drill bit connection device 8 is fixed to one end of the outer sleeve rod 3 along the length direction.

[0039] Specifically, the drill bit connecting device 8 is an internal threaded tube, which is connected to the drill bit by a threaded connection;

[0040] Specifically, the drill bit connecting device 8 is a three-jaw chuck, which is connected to the drill bit in a clamping manner.

[0041] Nuts 2 are fixed on the outer wall of the outer sleeve rod 3 and the inner wall of the inner sleeve rod 4. Bolts 1 are threadedly connected between the two nuts 2. The outer sleeve rod 3 and the inner sleeve rod 4 are relatively fixed by the bolts 1 and nuts 2.

[0042] In this embodiment, the stress measuring point 6 can be safely accommodated within the outer casing rod 3 through the relative axial movement of the inner casing rod 4 and the outer casing rod 3. This effectively prevents the measuring point from being damaged by friction and collision with the hole wall during the movement of the drill rod. When the drill rod reaches a predetermined depth in the borehole, the inner casing rod 4 is driven to move, allowing the stress measuring point 6 to be accurately extended through the opening 31 to the test position. After the device reaches the predetermined position, the stress measuring point 6 can be directly extended and contact the surface of the soft rock hole wall, thereby achieving direct and real-time measurement of in-situ stress, avoiding the core disturbance or installation delay problems that may be caused by traditional methods.

[0043] Furthermore, the in-situ stress testing device is particularly suitable for soft rock environments. By arranging multiple stress measuring points 6 along the axial direction, continuous or selected point measurements can be performed at different depths during a drilling process, and the in-situ stress distribution on the axial section of the soft rock borehole can be efficiently obtained. The extension and retraction of the measuring points can be completed by using the movement of the drill rod itself, without the need for additional complex operations or auxiliary tools, which significantly improves the testing efficiency and convenience.

[0044] The ground stress in the soft rock borehole is tested by a testing device located in the drill pipe, avoiding the tedious steps and complex instruments required for ground stress testing using traditional hydraulic fracturing and other technologies. This effectively fills the current gap in my country's soft rock ground stress testing devices. Through in-depth research on the ground stress distribution law of soft rocks, the stability of geotechnical engineering can be analyzed more accurately to ensure the safety of construction.

[0045] Example 2

[0046] See also Figure 1-Figure 3 The embodiment of the present invention provides a technical solution: a method for testing ground stress while drilling, which is implemented based on a ground stress testing device while drilling, and includes the following steps:

[0047] S1: When performing a geostress test, the drill bit is connected to the geostress testing device through the drill bit connection device 8, and a hole is drilled in soft rock using the drill bit. The geostress testing device is continuously advanced in the hole along with the drill bit in the drill rod. At this time, the inner casing rod 4 and the outer casing rod 3 remain relatively stationary, so that the stress measuring point 6 is at the bottom position of the inclined groove 41 on the surface of the inner casing rod 4. The outer casing rod 3 can better protect the stress measuring point 6 during the drilling process of the drill bit.

[0048] S2: When the drill bit reaches the specified depth and the in-situ stress testing device reaches the predetermined in-situ stress testing position, the in-situ stress test begins. The inner casing rod 4 is pushed forward inside the outer casing rod 3. At this time, the stress measuring point 6 moves outward along the inclined groove 41 on the surface of the inner casing rod 4. The opening 31 on the outer casing rod 3 constrains the stress sensor 9, so that the contact surface between the stress sensor 9 and the rock mass always remains parallel to the rock wall surface.

[0049] S3: When the inner casing rod 4 is advanced to the stress measuring point 6 and is in complete contact with the rock mass, the advancement is stopped, the outer casing rod 3 and the inner casing rod 4 are fixed, the ground stress is tested through the stress measuring point 6, and the stress measuring point 6 is connected to the data acquisition instrument through the wire 5 to collect the measured ground stress data of the soft rock;

[0050] S4: After the test is completed, the fixing of the sleeve rod is released, and the inner sleeve rod 4 is pulled back to the initial state, so that the stress measuring point 6 is retracted to the bottom position of the inclined groove 41 on the surface of the inner sleeve rod 4, avoiding damage to the stress measuring point 6 during the process of pulling the device out of the drill hole.

[0051] In this embodiment, after the stress measuring point 6 is retracted to the bottom position of the inclined slide 11, the outer sleeve rod 3 and the inner sleeve rod 4 are simultaneously pulled out of the borehole, and the drill bit is pulled out of the borehole under the action of the drill bit connecting device 8. Therefore, the device can repeatedly perform ground stress tests, and is easy to operate, greatly saving the cost of testing.

[0052] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for testing ground stress while drilling, characterized in that: It comprises an outer sleeve rod (3) and an inner sleeve rod (4) coaxially sleeved inside the outer sleeve rod (3), wherein the inner sleeve rod (4) is capable of axially moving along the length direction of the outer sleeve rod (3); A plurality of inclined grooves (41) are provided on the outer wall of the inner sleeve rod (4) at equal intervals along the axial direction, and a stress measuring point (6) is provided in each inclined groove (41); and an opening (31) is provided on the outer wall of the outer sleeve rod (3) at a position corresponding to each inclined groove (41); When the inner sleeve rod (4) is driven to move axially within the outer sleeve rod (3), the stress measuring point (6) can be synchronously driven to extend outward through the opening (31) for stress monitoring. When the stress measuring point (6) moves outward along the inclined groove (41) on the surface of the inner sleeve rod (4), the edge of the opening (31) on the outer sleeve rod (3) constrains it, so that the stress measuring point (6) finally extending from the opening (31) can face the rock wall surface.

2. The device for testing ground stress while drilling according to claim 1, characterized in that: The inner sleeve rod (4) is a tubular structure, with a strip hole (32) provided at the center, and a conductor (5) is arranged in the strip hole (32).

3. The device for testing ground stress while drilling according to claim 2, characterized in that: The stress measuring point (6) is composed of a stress sensor (9), a connecting rod (10) and a hook (7); the stress sensor (9) is arranged in the inclined chute (11); a side thereof opposite to the inclined chute (11) is preset with an oblique cut surface, so that the stress sensor (9) and the side opposite to the inclined chute (11) are in contact with each other.

4. The in-situ stress testing device according to claim 3, characterized in that: One end of the connecting rod (10) is fixed on the outer wall of the stress sensor (9), and the other end of the connecting rod (10) passes through the inner sleeve rod (4) and extends into the strip-shaped hole (32). The outer sleeve rod (3) is provided with an inclined sliding groove (11) used in conjunction with the connecting rod (10).

5. The device for testing ground stress while drilling according to claim 2, characterized in that: A drill bit connection device (8) is fixed to one end of the outer sleeve rod (3) along the length direction.

6. The in-situ stress testing device according to claim 1, characterized in that: Nuts (2) are fixed on the outer wall of the outer sleeve rod (3) and the inner wall of the inner sleeve rod (4), and a bolt (1) is threadedly connected between the two nuts (2). The outer sleeve rod (3) and the inner sleeve rod (4) are relatively fixed by the bolt (1) and the nut (2).

7. A method for testing ground stress while drilling, implemented based on a ground stress testing device while drilling according to any one of claims 4 to 6, characterized in that: The following steps are involved: S1: When performing a ground stress test, the drill bit is connected to the ground stress test device through the drill bit connection device (8), and a hole is drilled in soft rock using the drill bit. The ground stress test device is continuously advanced in the hole along with the drill bit in the drill rod. At this time, the inner casing rod (4) and the outer casing rod (3) remain relatively stationary, so that the stress measuring point (6) is located at the bottom position of the inclined groove (41) on the surface of the inner casing rod (4); S2: When the drill bit excavates to a specified depth and the in-situ stress test device reaches a predetermined in-situ stress test position, the in-situ stress test is started, and the inner casing rod (4) is pushed forward continuously inside the outer casing rod (3). At this time, the stress measuring point (6) moves outward along the inclined groove (41) on the surface of the inner casing rod (4), and the opening (31) on the outer casing rod (3) constrains the stress sensor (9), so that the contact surface between the stress sensor (9) and the rock mass is always kept parallel to the rock wall surface; S3: When the inner sleeve rod (4) is advanced to the stress measuring point (6) and is in complete contact with the rock mass, the advancement is stopped, the outer sleeve rod (3) and the inner sleeve rod (4) are fixed, the ground stress is tested through the stress measuring point (6), and the stress measuring point (6) is connected to the data acquisition instrument through the wire (5), thereby collecting the ground stress data of the soft rock; S4: After the test is completed, the fixing of the sleeve rod is released, and the inner sleeve rod (4) is pulled back to the initial state, so that the stress measuring point (6) is retracted to the bottom position of the inclined groove (41) on the surface of the inner sleeve rod (4), thereby avoiding damage to the stress measuring point (6) during the process of withdrawing the device from the drill hole.

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