A coring drill for geostress measurement

Abstract

The present application relates to the technical field of rock mechanics experiment, and more particularly to a coring drilling tool for in-situ stress measurement, a drill bit assembly, an outer pipe assembly, a stress detection assembly and an inner pipe assembly. The outer pipe assembly, the stress detection assembly and the inner pipe assembly are coaxially arranged in sequence from outside to inside. The inner pipe assembly comprises a first end and a second end. The second end extends to the outside of the outer pipe assembly along the axial direction of the outer pipe assembly, and the inner pipe assembly is detachably connected to one end of the stress detection assembly. The stress detection assembly is used for detecting the stress of a rock layer to be detected. The drill bit assembly is arranged at one end of the outer pipe assembly, and the drill bit assembly is detachably connected to the side of the stress detection assembly away from the second end of the inner pipe assembly. The strain change value is obtained through the stress detection assembly, so as to obtain the stress condition of the rock mass. Compared with the casing stress relief method, the present application does not need to separately pull out the drill, replace the drill bit to drill the measurement hole, and does not need to replace the equipment device. The process is simple, the operation is convenient, a large amount of process is saved, and the measurement efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rock mechanics experiment, and particularly relates to a coring drilling tool for in-situ stress measurement. BACKGROUND

[0002] The main task of geological exploration drilling is to obtain real geological cores so as to understand the real situation of the geological rock stratum to be explored; rock mechanics experiment is to determine the mechanical properties of engineering rock mass so as to analyze the stability of surrounding rock, and the combination of the two can provide a scientific basis for decision-making for the design of rock and soil engineering excavation. In the stability analysis of geological exploration drilling engineering, the in-situ stress state is one of the most important and fundamental factors.

[0003] The stress relief method is currently the most widely used in-situ stress measurement method with the longest development time and relatively mature technology at home and abroad, which mainly separates the rock sample from the surrounding rock mass or part of it, monitors the strain or displacement response of the relieved part, and then determines the in-situ stress tensor of the measurement point according to the relationship between the measured strain or displacement and the far-field stress of the surrounding rock. A typical way is the casing stress relief method.

[0004] The casing stress relief method is to realize the complete stress relief of the casing core by using the casing drilling method, so that the measurement point rock mass is separated from the in-situ stress, and thus the in-situ stress size and direction are determined. For details, see Chinese patent CN215292335U, which comprises a drill pipe outer tube and a strain sensor arranged at the center of the bottom of the drill hole. The drill pipe outer tube is internally provided with a drill pipe inner tube. A transmission pipe connected with the drilling machine is arranged between the drill pipe outer tube and the drill pipe inner tube. A connecting device is arranged between the outer side of the transmission pipe and the inner side of the drill pipe outer tube, and a centering device is arranged between the inner side of the transmission pipe and the drill pipe inner tube. The drilling structure composed of the drill pipe outer tube and the drill pipe inner tube, the connecting device comprises a rotatable bolt and a metal lock, and the centering device comprises a universal ball arranged between the outer side of the drill pipe inner tube and the inner side of the transmission pipe. The main measurement process is as follows: a measurement hole with composite conditions is obtained by drilling, after the drilling of the measurement hole is completed, the drill pipe inner tube is separated from the transmission pipe, then the strain sensor is placed in the measurement hole by using a long rod, and finally the data is read.

[0005] However, in the process of geological exploration with a depth of more than 500 meters, the rope coring drilling tool is mostly used before the two stress detections. The stress test of the existing stress relief method needs to be completed in cooperation with the single-pipe coring drilling tool. That is, under the condition of rope coring, the placement and measurement of the measurement element cannot be realized by single-pipe coring, and the drilling needs to be carried out separately. Then, the drill pipe is pulled out, and the stress detection is carried out by the stress measurement device. Therefore, it is difficult to carry out the in-situ stress test by the stress relief method in the deep hole with a depth of more than 500 meters, the process is complex and tedious, and the construction period is too long. SUMMARY

[0006] (I) Technical problems to be solved

[0007] In view of the above-mentioned defects and deficiencies of the prior art, the present application provides a coring drilling tool for ground stress measurement, which solves the technical problems that it is difficult to perform stress relief method ground stress test in a deep hole with a depth exceeding meters, the process is complex and tedious, and the construction period is too long.

[0008] (II) Technical solutions

[0009] In order to achieve the above-mentioned purpose, the main technical solutions adopted by the present application include:

[0010] The present application provides a coring drilling tool for ground stress measurement, a drill bit assembly, an outer pipe assembly, a stress detection assembly and an inner pipe assembly, the outer pipe assembly, the stress detection assembly and the inner pipe assembly are coaxially arranged in sequence from the outside to the inside;

[0011] The inner pipe assembly includes a first end close to the drill bit assembly and a second end arranged opposite to the first end;

[0012] The second end of the inner pipe assembly extends to the outside of the outer pipe assembly along the axial direction of the outer pipe assembly, and the inner pipe assembly is detachably connected to one end of the stress detection assembly, and the stress detection assembly is used for detecting the stress of the rock layer to be detected;

[0013] The drill bit assembly is fixedly arranged at one end of the outer pipe assembly, and the drill bit assembly is detachably connected to the side of the stress detection assembly away from the second end of the inner pipe assembly.

[0014] Optionally, the stress detection assembly includes a slotted joint unit and a sensor unit connected in the axial direction, and the slotted joint unit and the sensor unit form a stress detection cylinder after being connected, and a mud flow channel is formed between the inner side wall of the stress detection cylinder and the outer side wall of the inner pipe assembly for the mud to enter;

[0015] One end of the slotted joint unit is connected to the drill bit assembly, and one end of the sensor unit is connected to the inner side wall of the inner pipe assembly;

[0016] The sensor unit can protrude or retract through the outer pipe assembly along the radial direction of the stress detection cylinder, and the slotted joint unit can protrude or retract through the outer pipe assembly along the radial direction of the stress detection cylinder.

[0017] Optionally, a connecting pipe is further arranged between the slotted joint unit and the sensor unit;

[0018] The two ends of the connecting pipe are detachably connected to the slotted joint unit and the sensor unit, respectively.

[0019] Optionally, the slitting unit comprises a drill bit connecting pipe, a slitting elastic piece, a first valve, a blade and two first mounting joints;

[0020] A slitting connecting pipe is arranged between the drill bit connecting pipe and the connecting pipe, and the two ends of the slitting connecting pipe respectively abut against the side surfaces of the drill bit connecting pipe and the connecting pipe, the slitting connecting pipe and the inner pipe assembly form part of the mud flow channel, and the slitting elastic piece is sleeved outside the slitting connecting pipe and abuts against the outer sidewall of the slitting connecting pipe;

[0021] One end of the drill bit connecting pipe is detachably connected with the drill bit assembly, the other end of the drill bit connecting pipe is detachably connected with one of the first mounting joints, the first annular groove is formed between the drill bit connecting pipe and one of the first mounting joints to place one end of the slitting elastic piece, and the other end of the slitting elastic piece is placed between the connecting pipe and the other of the first mounting joints to form the other end of the second annular groove;

[0022] A first through hole for placing the first valve is arranged in the bottom of the slitting connecting pipe, and the maximum pressure that the first valve can withstand is P2;

[0023] The bottom end surface of the blade abuts against the top outer sidewall of the slitting elastic piece.

[0024] Optionally, the blade comprises a circular-arc-shaped blade body and a vertical cutter;

[0025] The inner arc surface of the blade body abuts against the slitting elastic piece, and the outer arc surface of the blade body is fixedly connected with the cutter.

[0026] Optionally, the sensor unit comprises a mounting pipe, a sensing rubber, a second valve, a sensor body and two second mounting joints;

[0027] A sensing connecting pipe is arranged between the mounting pipe and the connecting pipe, and the two ends of the sensing connecting pipe respectively abut against the side surfaces of the mounting pipe and the connecting pipe, the sensing connecting pipe and the inner pipe assembly form part of the mud flow channel, and the sensing rubber is sleeved outside the sensing connecting pipe and abuts against the outer sidewall of the sensing connecting pipe;

[0028] One end of the mounting pipe is detachably connected with the inner pipe assembly, the other end of the mounting pipe is detachably connected with one of the second mounting joints, the third annular groove is formed between the mounting pipe and one of the second mounting joints to place one end of the sensing rubber, and the other end of the sensing rubber is placed between the connecting pipe and the other of the second mounting joints to form the other end of the fourth annular groove;

[0029] The bottom of the sensing pipe is provided with a second through hole for placing the second valve, the maximum pressure that the second valve can withstand is P1, and P2 is greater than P1;

[0030] The bottom end surface of the sensor body is in abutment with the top outer sidewall of the sensing rubber.

[0031] Optionally, the first mounting joint is a cylindrical structure;

[0032] The first mounting joint has a threaded hole, a first mounting hole, an inclined hole and a second mounting hole connected in sequence;

[0033] The threaded hole can be respectively matched with the threaded connection of the drill bit connecting pipe, the connecting pipe and the end of the rear end;

[0034] The diameter of the first mounting hole is greater than the diameter of the second mounting hole, and the diameter of the second mounting hole is the same as the diameter of the slitting pipe or the sensing pipe;

[0035] The second mounting joint has the same structure as the first mounting joint.

[0036] Optionally, the outer wall of the first connecting mounting head and the end close to the threaded hole are provided with a sealing annular groove.

[0037] Optionally, the sensor unit further comprises a power module, a signal acquisition module and a sound wave emission module;

[0038] The sensor body is connected to the power module, the signal acquisition module and the sound wave emission module in sequence through wires, and the strain change value measured by the sensor body is sent to the ground through the drill pipe through the sound wave emission module.

[0039] Optionally, the outer pipe assembly comprises a first outer pipe and a second outer pipe;

[0040] The first outer pipe and the second outer pipe are detachably connected at the end, the first outer pipe is arranged on the side close to the drill bit assembly, and the first outer pipe is provided with a first window and a second window for the slitting unit and the sensor unit to extend out, respectively.

[0041] (Three) beneficial effects

[0042] The core drilling tool for ground stress measurement has the advantages that in the process of normal rope core drilling, the stress detection assembly is used to obtain the strain change value, so that the rock mass stress condition is obtained, compared with the casing stress relief method, the core drilling tool does not need to be pulled out separately, a drill bit is replaced to drill a measuring hole, equipment devices do not need to be replaced, the process is simple, operation is convenient, a large amount of process is saved, and the measuring efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is the overall structure diagram of the core drilling tool for ground stress measurement of the present application;

[0044] Figure 2 is Figure 1 the enlarged schematic view of the internal structure;

[0045] Figure 3 is the structural schematic view of the slit unit;

[0046] Figure 4 is the side view of the slit unit;

[0047] Figure 5 is the structural schematic view of the first mounting joint;

[0048] Figure 6 is the structural schematic view of the sensor unit;

[0049] Figure 7 is the partial structural schematic view of the mounting pipe;

[0050] Figure 8 is the partial structural schematic view of the outer pipe assembly.

[0051]

BRIEF DESCRIPTION OF DRAWINGS

[0052] 1: Drill bit assembly; 2: Outer tube assembly; 21: First outer tube; 211: First window; 212: Second window; 213: External connecting pipe thread; 214: Rib groove; 22: Second outer tube; 3: Stress detection assembly; 31: Cutting unit; 311: Drill bit connecting pipe; 312: Cutting elastic element; 313: First valve; 314: Blade; 3141: Blade body; 3142: Cutting blade; 315: First mounting joint; 3151: Threaded hole; 3152: First mounting hole; 3153: Angled hole; 3154: Second mounting hole; 3155 316: Rounded corner; 32: Slit connector; 32: Sensor unit; 321: Mounting tube; 3211: Cylindrical outer hole; 3212: Connecting thread; 3213: First platform hole; 3214: Third platform hole; 3216: Second platform hole; 3215: Connecting internal thread; 322: Sensing rubber; 323: Second valve; 324: Sensor body; 325: Second mounting connector; 326: Sensing connector; 33: Connecting tube; 4: Inner tube assembly; 5: Power module; 6: Signal acquisition module; 7: Acoustic wave emission module; 8: Wire; 9: Spring-loaded chamber. Detailed Implementation

[0053] To better explain and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. In this document, directional terms such as "upper," "lower," "inner," "outer," "front," and "rear" are used interchangeably with other directional terms. Figure 1 The orientation is used as a reference. Figure 1 The direction of the drilling of the middle drill bit assembly 1 is defined as "forward"; the direction of the outer tube assembly 2 relative to the inner tube assembly 4 is defined as "outer"; and the position of the second window 212 relative to the first outer tube 21 is defined as "upper".

[0054] See Figures 1-8 As shown, a coring drill for measuring ground stress includes a drill bit assembly 1, an outer tube assembly 2, a stress detection assembly 3, and an inner tube assembly 4. The outer tube assembly 2, the stress detection assembly 3, and the inner tube assembly 4 are nested sequentially from the outside to the inside and arranged coaxially.

[0055] Further, see Figure 1 and Figure 4 As shown, the outer tube assembly 2 includes a first outer tube 21 and a second outer tube 22 arranged in a front-to-back configuration. The rear end of the first outer tube 21 is detachably connected to the front end of the second outer tube 22 via a geological thread, forming the drill bit outer tube structure. Specifically, the first outer tube 21 is fixedly disposed on one side close to the drill bit assembly 1, and the top sidewall of the first outer tube 21 is provided with a first window 211 and a second window 212 for the cutting unit 31 and the sensor unit 32 to extend out, respectively.

[0056] Further, see Figure 8As shown in the figure, the outer surface of the first outer tube 21 is in close contact with the rock wall. The first outer tube 21 is provided with a rib groove 214 which is in close cooperation with the rib on the signal acquisition module 6 (not shown in the figure) to fix the signal acquisition module 6 so that it moves with the first outer tube 21 and the mounting tube 321, avoiding shaking and interfering with signal acquisition.

[0057] Referring to Figure 1 As shown in the figure, the inner tube assembly 4 includes a first end and a second end arranged opposite to each other. The first end is located close to the drill bit assembly 1 and is provided with a through hole which is in communication with the drill bit assembly 1. It should be noted that the through hole of the first end is in communication with the inner tube to realize coring and directly store the rock core drilled by the drill bit assembly 1 into the inner cavity of the inner tube assembly 4.

[0058] Moreover, the second end (rear end) of the inner tube assembly 4 extends to the outside of the outer tube assembly 2 along the axial direction of the outer tube assembly 2 and is rotatably connected with the snap chamber 9. It should be noted that the connection mode of the snap chamber 9 and the inner tube assembly 4 is the same as that of the conventional wireline coring drill tool, which will not be described in detail here. The inner tube assembly 4 is fixedly connected with the drill rod rig through the snap chamber 9. The inner tube assembly 4 is placed inside the outer tube structure of the drill tool, and its connection structure is similar to the conventional wireline coring structure. Specifically, one end of the snap chamber 9 of the inner tube assembly 4 is connected with the drill rig through the drill rod (not shown in the figure), and the other end of the inner tube assembly 4 extends close to the drill bit assembly 1 and is stationary relative to the outer tube structure of the drill tool. In addition, the stress detection assembly 3 is arranged between the inner tube assembly 4 and the outer tube assembly 1, and the other end of the snap chamber 9 of the inner tube assembly 4 is detachably connected with one end of the stress detection assembly 3. Specifically, one end of the stress detection assembly 3 is connected with the drill bit assembly 1, and the other end is threadedly connected with the other end of the snap chamber 9 of the inner tube assembly 4 through the mounting tube 321, that is, the stress detection assembly 3 rotates relative to the inner tube assembly 4. The inner tube assembly 4, the stress detection assembly 3, the drill bit assembly 1 and the outer tube assembly 2 interact to form a drill tool capable of coring. When the stress of the rock layer needs to be detected, the stress detection assembly 3 can move with the coring drill tool to detect the stress of the rock layer to be detected, without the need to lift the pipe or replace the drill pipe multiple times. The efficiency is improved.

[0059] Referring to Figure 1 and Figure 2 As shown in the figure, the drill bit assembly 1 is fixedly arranged at one end of the outer tube assembly 2, and the rear end of the drill bit assembly 1 is detachably connected with the side away from the second end of the inner tube assembly 4 through a thread. Specifically, when the drill rig rotates and transmits the drilling pressure through the outer tube assembly 2, the drill tool will start to rotate, drill and cut, and core accordingly.

[0060] Further, the stress detection assembly 3 comprises a slit unit 31 and a sensor unit 32 connected in an axial direction. The slit unit 31 and the sensor unit 32 are connected to form a stress detection cylinder, and an annular mud flow channel is formed between the inner side wall of the stress detection cylinder and the outer side wall of the inner pipe assembly 4 to allow mud to enter the drill bit assembly 1 to discharge the core. In addition, the mud is injected by a mud pump on the ground, and the mud pump can adjust the pressure of the mud to match the subsequent stress measurement.

[0061] Further, a connecting pipe 33 is arranged between the slit unit 31 and the sensor unit 32. The two ends of the connecting pipe 33 are respectively detachably connected with the slit unit 31 and the sensor unit 32.

[0062] In the embodiment, one end of the slit unit 31 is fixedly connected with the drill bit assembly 1, and one end of the sensor unit 32 is connected with the elastic clamping chamber 9 of the inner pipe assembly 4.

[0063] Further, the slit unit 31 comprises a drill bit connecting pipe 311, a slit elastic member 312, a first valve 313, two first mounting joints 315, and a plurality of blades 314.

[0064] Specifically, one end of the drill bit connecting pipe 311 is detachably connected with the drill bit assembly 1 by screw threads, and the other end of the drill bit connecting pipe 311 is detachably connected with the front first mounting joint 315 by screw threads. The drill bit connecting pipe 311 and the front first mounting joint 315 form a first annular groove to accommodate one end of the slit elastic member 312, and the other end of the slit elastic member 312 is accommodated in the second annular groove formed between the connecting pipe 33 and the other first mounting joint 315. Preferably, the slit elastic member 312 is a slit rubber ring, which has good elasticity, small wear degree, and low cost.

[0065] Further, a slit connecting pipe 316 is arranged between the drill bit connecting pipe 311 and the connecting pipe 33. The two ends of the slit connecting pipe 316 are thin-walled connecting ears, which are respectively inserted into the first annular groove and the second annular groove, and the two end faces of the slit connecting pipe 316 are respectively abutted and mounted with the side faces of the drill bit connecting pipe 311 and the connecting pipe 33. The slit connecting pipe 316 is part of the mud flow channel between the slit elastic member 312 and the inner pipe assembly 4, and the slit elastic member 312 is sleeved outside the slit connecting pipe 316 and abuts with the outer side wall of the slit connecting pipe 316. Moreover, the two ends of the slit elastic member 312 are also inserted into the first annular groove to press the connecting ears of the slit connecting pipe 316 against the outer side wall of the drill bit connecting pipe 311.

[0066] Specifically, the bottom of the slitting adapter 316 is provided with a first through hole for placing the first valve 313, and the maximum pressure that the first valve 313 can withstand is P1. The slitting adapter 316 is provided to provide a channel for the slurry and to provide the function of supporting and directly transmitting pressure to the slitting elastic member 312.

[0067] Further, the blade 314 includes a circular-arc-shaped blade body 3141 and a vertical cutter 3142. The inner arc surface of the blade body 3141 abuts against the slitting elastic member 312, and the outer arc surface of the blade body 3141 is fixedly connected with the cutter 3142.

[0068] Referring to Figure 3 When the slurry pump controls the pressure of the slurry to reach the opening pressure P1 of the first valve 313, the first valve 313 is opened, the slurry flows into the inside of the slitting adapter 316 through the first valve 313, the slitting elastic member 312 is deformed by the pressure of the slurry and starts to expand, and the blade 314 also moves upward along the radial direction of the slitting elastic member 312 due to the deformation of the slitting elastic member 312. The blade 314 extends out of the first window 211 of the first outer pipe 21 and can cut a 1mm slit on the rock wall. When the slurry pressure is less than the opening pressure P2 of the first valve 313, the slitting elastic member 312 returns to the original position due to the deformation, and the blade 314 also moves downward along the radial direction of the slitting elastic member 312 and returns to the original position from the surface of the rock wall due to the return of the slitting elastic member 312, thereby achieving the effect of releasing the stress. The operation is simple and can be easily realized, and the excessive process is avoided.

[0069] Referring to Figure 5 The first mounting joint 315 is a cylindrical structure. The first mounting joint 315 has a threaded hole 3151, a first mounting hole 3152, an inclined hole 3153 and a second mounting hole 3154 connected in sequence. The threaded hole 3151 can be screwed with the drill bit connecting pipe 311, the connecting pipe 33 and the end of the rear end, respectively. The diameter of the first mounting hole 3152 is greater than the diameter of the second mounting hole 3154, and the diameter of the second mounting hole 3154 is the same as the diameter of the slitting adapter 316 or the sensing adapter 326.

[0070] The outer wall of the first connecting mounting head and the end face near the threaded hole are both provided with a sealing annular groove. Both of the sealing annular grooves are used for placing O-rings to form a sealed environment. That is, the cutting seam elastic member 312 or the sensing rubber 322 can be provided with a sealed environment, and when the two contact the mud, the rubber is more beneficial to expand, and thus the deformation effect of the cutting seam elastic member 312 or the sensing rubber 322 is better. The threads on the threaded hole 3151 can be threadedly connected with the drill bit connecting pipe 311, the connecting pipe 33 and the mounting pipe 321, and the drilling pressure transmitted by the drilling machine is transmitted to the drill bit assembly 1. The first mounting hole 3152 is a large inner hole of the cutting seam connecting pipe 316, and the diameter thereof is greater than that of the cutting seam connecting pipe 316 and less than that of the cutting seam elastic member 312 or the sensing rubber 322. The diameter of the second mounting hole 3154 is equal to the outer diameter of the cutting seam connecting pipe 316. The inclined hole 3153 and the round corner 3155 are arranged between the first mounting hole 3152 and the second mounting hole 3154 to buffer the rubber, so as to avoid damaging the rubber by the stepped surface and the sharp corner. At the same time, the diameter design also locks and presses the end part of the rubber in the cutting seam connecting pipe 316, so as to fix the axial movement of the cutting seam elastic member 312. Further, a through hole is arranged in the cutting seam connecting pipe 316 as a cable passage, which is the structure of the second mounting joint 325.

[0071] Referring to Figure 6 As shown, the sensor unit 32 can be extended or retracted along the radial direction of the stress detection cylinder through the outer pipe assembly 2, and the cutting seam unit 31 can be extended or retracted along the radial direction of the stress detection cylinder through the outer pipe assembly 2.

[0072] Further, the sensor unit 32 comprises a mounting pipe 321, a sensing rubber 322, a second valve 323, a sensor main body 324 and two second mounting joints 325.

[0073] Further, a sensing connecting pipe 326 is arranged between the mounting pipe 321 and the connecting pipe 33. The two ends of the sensing connecting pipe 326 are respectively in abutment with the side surfaces of the mounting pipe 321 and the connecting pipe 33. The sensing connecting pipe 326 and the inner pipe assembly 4 form part of a mud flow channel, and the sensing rubber 322 is sleeved outside the sensing connecting pipe 326 and in abutment with the outer side wall of the sensing connecting pipe 326. One end of the mounting pipe 321 is detachably connected with the inner pipe assembly 4, and the other end of the mounting pipe 321 is detachably connected with a second mounting joint 325. A third annular groove is formed between the mounting pipe 321 and the second mounting joint 325 to accommodate one end of the sensing rubber 322, and the other end of the sensing rubber 322 is accommodated in the other end of a fourth annular groove formed between the connecting pipe 33 and the other second mounting joint 325.

[0074] In the embodiment, the bottom of the sensing connector 326 is provided with a second through hole for placing the second valve 323. The maximum pressure that the second valve 323 can withstand is P1, and P2 is greater than P1. The bottom end surface of the sensor body 324 is in abutment with the top outer sidewall of the sensing rubber 322. Optionally, the lower end of the sensor body 324 is circularly arc-shaped and cooperates with the outer surface of the sensing rubber 322.

[0075] Specifically, the sensor body 324 is placed outside the sensing connector 326 and faces the second window 23 of the first outer pipe 21. The inner hole of the sensing connector 326 and the outer surface of the pipe body of the inner pipe assembly 4 constitute a part of the mud flow channel. When the mud pressure reaches the opening pressure P2 of the second valve 323, the second valve 323 is opened, the mud flows into the inside of the sensing connector 326 through the second valve 323, the sensing rubber 322 is deformed by the pressure of the mud and starts to expand, the sensor body 324 moves upward along the radial direction of the sensing rubber 322 due to the deformation of the sensing rubber 322, the sensor body 324 extends out of the second window 212 of the first outer pipe 21 and can contact the rock wall to measure the strain value of the rock wall at this time; when the mud pressure is less than the opening pressure P2 of the second valve 323, the sensing rubber 322 returns to the original position due to the deformation reset, and the sensor body 324 also moves downward along the radial direction of the sensing rubber 322 due to the reset of the sensing rubber 322 and returns to the original position from the surface of the rock wall, so that the strain change value of the ground stress can be measured.

[0076] Further, the sensor unit 32 further comprises a power module 5, a signal acquisition module 6 and a sound wave emitting module 7. The sensor body 324 is connected with the power module 5, the signal acquisition module 6 and the sound wave emitting module 7 in sequence through the wire 8, and the strain change value measured by the sensor body 324 is transmitted to the ground through the sound wave emitting module 7 and the drill pipe. In addition, the communication mode between the power module 5, the signal acquisition module 6 and the sound wave emitting module 7 is the existing conventional technology, which will not be described in detail here.

[0077] Referring to Figure 6 As shown in the figure, the sensor body 324 is connected with the power module 5, the signal acquisition module 6 and the sound wave emitting module 7 in sequence through the insulated wire, and the strain change value measured by the sensor body 324 is transmitted to the ground through the sound wave emitting module 7 and the drill pipe (not shown in the figure). After the sound wave module on the ground receives the signal of the sound wave emitting module 7, the single-chip microcomputer system collects and processes the data and then transmits them through the wireless mode to realize the communication with the ground computer. In this way, the wireless transmission is realized, the ground stress can be understood in real time, and the measurement efficiency is higher.

[0078] Specifically, Figure 4The front side structure diagram of the cutting device is shown. The ground stress measurement mainly adopts drilling on the rock layer, that is, cutting several parallel to the hole axis direction cutting seams around the hole center at a certain angle on the hole wall, so that the normal stress of the surface on both sides of the cutting seam is completely released, and the normal strain change value of the rock mass surface on one side of the cutting seam before and after stress release is measured, and the rock stress condition is calculated according to the elastic theory. In the embodiment, before cutting, the pressure value P1 of the second valve 323 on the pressure sensing connection pipe 326 of the hydraulic control mud is first measured, the second valve 323 is opened, the mud flows into the inside of the sensing connection pipe 326 through the second valve 323, the sensing rubber 322 is deformed by the pressure of the mud, the sensor body 324 also moves upward along the radial direction of the sensing rubber 322 with the deformation of the sensing rubber 322, the contact type strain sensor body 324 is stretched out from the second window 212 of the first outer pipe 21, and the strain sensor body 324 is closely attached to the rock wall of the rock mass near the preset cutting seam, and then the strain value before cutting is measured, and the data is recorded after the strain signal is stable. Next, the pressure value of the mud pump is continuously increased to P2, at this time, the first valve 313 is opened, the cutting elastic element 312 is expanded, and the blade 314 will open a 1mm slot, and then the pressure of the mud pump is reduced to P1, so that the cutting elastic element 312 is retracted to the initial position, and the blade 314 is directly withdrawn from the first window 211. At this time, the strain sensor body 324 still contacts the rock wall, and is measured again until the output signal is stable again, and the pressure of the mud pump is reduced to be less than <P1, at this time, the sensor body 324 is retracted from the rock wall, and the data signal is always relied on the sound wave emission module 7 to control the first valve body to change the strain value, so that the normal stress of the cutting seam is calculated. Assuming that the horizontal direction of the hole cross section is x axis and the vertical upward direction is z axis, let S zz and S xz be the rock stress components of the hole cross section before the hole is formed, then the stress state of the hole wall at the position with the angle of 0 with the z axis is:

[0079]

[0080] If the strain of the part is measured after cutting, the elastic modulus of the rock mass is E, then:

[0081] σθ=Eε.

[0082] It should be noted that the second mounting joint 325 has the same structure as the first mounting joint 315. The purpose is to facilitate production, simplify the process and the adaptation of parts.

[0083] Further, the plurality of blades 314 are arranged at intervals along the circumferential direction of the slit elastic member 312, and the inner side end surface of each blade 314 abuts against the outer side wall of the slit elastic member 312.

[0084] In theory, at least three independent slits are arranged for individual measurement, and a two-dimensional stress tensor of the borehole cross section can be calculated from the three independent normal stress results.

[0085] Reference Figure 7 As shown, the mounting pipe 321 includes a cylindrical outer hole 3211, a connecting thread 3212, a first platform hole 3213, a second platform hole 3216, a third platform hole 3214, a connecting internal thread 3215, and the cylindrical outer hole 3211 and the inclined hole 3153 in the second mounting joint 325 form an annular groove for locking the end of the pressure sensing rubber 322, the connecting thread 3212 is connected with the threaded hole 3151 in the second mounting joint 325, and the connecting internal thread 3215 is connected with the thread of the elastic clamping chamber 9 of the inner pipe assembly 4.

[0086] The core drilling tool for ground stress measurement of the present application obtains the strain change value through the stress detection assembly 3 during normal rope core drilling, thereby obtaining the rock mass stress condition.

[0087] Further, the present design adopts hydraulic drive control sensor and the action sequence of the blades 314, and has simple structure, which is more suitable for small space drilling devices, especially for core drilling devices.

[0088] Moreover, the drilling groove is rotated by an angle of 120 degrees in a clockwise direction. Then the testing process can be repeated in the above-mentioned manner. The in-situ stress on the plane will be measured. The operation process is simple, and the drill bit does not need to be replaced and the drilling sleeve does not need to be drilled. The in-situ stress measurement is integrated in the rope coring, and the in-situ stress of the rock stratum can be measured at a long distance. The acoustic wave transmission, wireless transmission, real-time data updating, and higher accuracy are adopted; the drilling, coring, and in-situ stress measurement are synchronously performed, and more data information is obtained.

[0089] In the description of the present application, it is to be understood that the terms "first", "second", "third" and the like, are used merely to describe the respective features and do not imply or imply relative importance or a specific number of the features indicated. Therefore, the features defined as "first", "second", "third" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0090] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0091] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature is "above", "over" and "on" the second feature, which can be directly above or obliquely above the first feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature is "below", "under" and "under" the second feature, which can be directly below or obliquely below the first feature, or only indicates that the horizontal height of the first feature is lower than that of the second feature.

[0092] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0093] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can modify, modify, replace and modify the above-described embodiments within the scope of the present application.

Claims

1. A coring drill for geostress measurement, characterized in that, The drill bit assembly (1), the outer tube assembly (2), the stress detection assembly (3) and the inner tube assembly (4) are coaxially arranged from outside to inside; The inner tube assembly (4) comprises a first end close to the drill bit assembly (1) and a second end opposite to the first end; The second end of the inner tube assembly (4) extends to the outside of the outer tube assembly (2) along the axial direction of the outer tube assembly (2), and the inner tube assembly (4) is relatively rotatably installed at one end of the stress detection assembly (3) for detecting the stress of the rock layer to be detected; The drill bit assembly (1) is fixedly arranged at one end of the outer tube assembly (2), and the drill bit assembly (1) is detachably connected to the side of the stress detection assembly (3) away from the second end of the inner tube assembly (4); The stress detection assembly (3) comprises a slitting unit (31) and a sensor unit (32) connected along the axial direction, and the slitting unit (31) and the sensor unit (32) form a stress detection cylinder after being connected, and a mud flow channel is formed between the inner side wall of the stress detection cylinder and the outer side wall of the inner tube assembly (4) for the mud to enter; One end of the slitting unit (31) is connected to the drill bit assembly (1), and one end of the sensor unit (32) is connected to the inner side wall of the inner tube assembly (4); The sensor unit (32) can extend or retract through the outer tube assembly (2) along the radial direction of the stress detection cylinder, and the slitting unit (31) can extend or retract through the outer tube assembly (2) along the radial direction of the stress detection cylinder; The slitting unit (31) comprises a drill bit connecting pipe (311), a slitting elastic element (312), a first valve (313), two first mounting joints (315) and a plurality of blades (314); The slitting connecting pipe (316) is arranged between the drill bit connecting pipe (311) and the connecting pipe (33), and the two ends of the slitting connecting pipe (316) respectively abut against the side surfaces of the drill bit connecting pipe (311) and the connecting pipe (33), the slitting connecting pipe (316) and the inner tube assembly (4) form part of the mud flow channel, and the slitting elastic element (312) is sleeved outside the slitting connecting pipe (316) and abuts against the outer side wall of the slitting connecting pipe (316); One end of the drill bit connecting pipe (311) is detachably connected to the drill bit assembly (1), the other end of the drill bit connecting pipe (311) is detachably connected to one of the first mounting joints (315), the drill bit connecting pipe (311) and one of the first mounting joints (315) form a first annular groove for placing one end of the slitting elastic element (312), and the other end of the slitting elastic element (312) is placed between the connecting pipe (33) and the other first mounting joint (315) to form the other end of a second annular groove; The bottom of the slit connecting pipe (316) is provided with a first through hole for placing the first valve (313), and the maximum pressure that the first valve (313) can withstand is P2; A plurality of the blades (314) are arranged along the circumference of the slit elastic element (312), and the inner side end surface of each blade (314) abuts against the outer side wall of the slit elastic element (312).

2. The core drill for ground stress measurement according to claim 1, wherein, A connecting pipe (33) is further arranged between the slit unit (31) and the sensor unit (32); The two ends of the connecting pipe (33) are respectively detachably connected with the slit unit (31) and the sensor unit (32).

3. The coring drill for geostress measurement according to claim 2, wherein, The blade (314) comprises a circular-arc-shaped blade body (3141) and a vertical-shaped cutter (3142); The inner side arc surface of the blade body (3141) abuts against the slit elastic element (312), and the outer side arc surface of the blade body (3141) is fixedly connected with the cutter (3142).

4. The coring drill for ground stress measurement according to claim 3, wherein, The sensor unit (32) comprises a mounting pipe (321), a sensing rubber (322), a second valve (323), a sensor body (324) and two second mounting connectors (325); A sensing connecting pipe (326) is arranged between the mounting pipe (321) and the connecting pipe (33), and the two ends of the sensing connecting pipe (326) respectively abut against the side surfaces of the mounting pipe (321) and the connecting pipe (33), the sensing connecting pipe (326) and the inner pipe assembly (4) form part of the mud flow channel, the sensing rubber (322) is sleeved on the outside of the sensing connecting pipe (326) and abuts against the outer side wall of the sensing connecting pipe (326); One end of the mounting pipe (321) is detachably connected with the inner pipe assembly (4), the other end of the mounting pipe (321) is detachably connected with one of the second mounting connectors (325), the mounting pipe (321) and one of the second mounting connectors (325) form a third annular groove for placing one end of the sensing rubber (322), and the other end of the sensing rubber (322) is placed between the connecting pipe (33) and the other second mounting connector (325) to form the other end of a fourth annular groove; The bottom of the sensing connecting pipe (326) is provided with a second through hole for placing the second valve (323), the maximum pressure that the second valve (323) can withstand is P1, and P2 is greater than P1; The bottom end surface of the sensor body (324) abuts against the top outer side wall of the sensing rubber (322).

5. The coring drill for geostress measurement according to claim 4, wherein, The first mounting connector (315) is a cylindrical structure; The first mounting connector (315) has a threaded hole (3151), a first mounting hole (3152), an inclined hole (3153) and a second mounting hole (3154) connected in sequence; The threaded hole (3151) can be screwed with the drill bit connecting pipe (311), the connecting pipe (33) and the end of the rear end, respectively. The diameter of the first mounting hole (3152) is larger than the diameter of the second mounting hole (3154), and the diameter of the second mounting hole (3154) is the same as the diameter of the slitting adapter (316) or the sensing adapter (326); The second mounting joint (325) is the same structure as the first mounting joint (315).

6. The core drill for ground stress measurement according to claim 5, wherein, The outer wall of the first connecting mounting head and the end close to the threaded hole are provided with a sealing annular groove.

7. The core drill for ground stress measurement according to claim 6, characterized in that, The sensor unit (32) further comprises a power module (5), a signal acquisition module (6) and a sound wave emitting module (7). The sensor main body (324) is connected with the power module (5), the signal acquisition module (6) and the sound wave emitting module (7) through wires in sequence, and the strain change value measured by the sensor main body (324) is sent to the ground through the drill pipe through the sound wave emitting module (7).

8. The core drill for ground stress measurement according to claim 1, wherein, The outer pipe assembly (2) comprises a first outer pipe (21) and a second outer pipe (22); The first outer pipe (21) is detachably connected with the end of the second outer pipe (22), the first outer pipe (21) is arranged on one side close to the drill bit assembly (1), and the side wall of the first outer pipe (21) is respectively provided with a first window (211) and a second window (212) for the slitting unit (31) and the sensor unit (32) to extend out.

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