Rock block pre-pressing fracture distribution and grouting reinforcement slurry diffusion experiment device and method

Abstract

The invention relates to the technical field of rock engineering, in particular to a rock block pre-pressing crack distribution and grouting reinforcement slurry diffusion experiment device and method.The device comprises a test box, and the test box comprises a base, a first rigid baffle, a second rigid baffle, a first elastic baffle, a second elastic baffle, a limiting base and a side base; the first rigid baffle, the second rigid baffle, the first elastic baffle and the second elastic baffle are all arranged on the base, the side seats are fixed to the two sides of the first rigid baffle and the two sides of the second rigid baffle, the limiting seat is arranged on the side seats, and the stay wire sensor is arranged on the surface of one side of the limiting seat. A stay wire of the stay wire sensor is connected to the other limiting seat opposite to the stay wire sensor; the device disclosed by the invention has the beneficial effects that the device is a random crack generation device which enables the rock mass to keep the integrity after bearing and crushing expansion, the diffusion rule of slurry is researched according to the combination of a grouting test and a CT scanning technology, and the characteristic of onsite rock mass crack generation randomness is met.

Description

Technical Field

[0001] The invention relates to the technical field of rock engineering, in particular to a device and method for experimenting on distribution of pre-compression cracks in rock blocks and diffusion of grouting reinforcement slurry. Background Art

[0002] Cracks are common in underground rock masses, and their development degree has an important influence on the construction and operation of underground projects, and sometimes even a decisive factor. In order to improve the integrity and stability of fractured rock masses, grouting reinforcement is often required. Some key parameters in the grouting reinforcement process, such as grouting hole arrangement, slurry diffusion radius, grouting pressure, and slurry injection volume, are closely related to the distribution of cracks in the rock mass. Therefore, the distribution characteristics of rock mass cracks and the slurry diffusion law in grouting reinforcement are of great significance in guiding engineering practice.

[0003] Due to the concealment of underground rock mass and the complexity of cracks in the rock mass, it is difficult to study the cracks in the rock mass with the help of field observations. The field results have the problems of limited range and low precision. Indoor experiments have become one of the effective means to solve this problem. However, most of the cracks in existing experiments are obtained by artificial prefabrication, and the cracks obtained are mostly regular, which cannot meet the characteristics of random generation of rock mass cracks on site. For this reason, the present invention proposes a rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device and method to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device and method to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device, the rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device comprising: a test box, the test box comprising a base, a first rigid baffle, a second rigid baffle, a first elastic baffle, a second elastic baffle, a limit seat and a side seat, the first rigid baffle, the second rigid baffle, the first elastic baffle and the second elastic baffle are all arranged on the base;

[0006] Side seats are fixed on both sides of the first rigid baffle plate and the second rigid baffle plate, and a limit seat is arranged on the side seat. A pull wire sensor is arranged on one side surface of the limit seat, and the pull wire of the pull wire sensor is connected to another limit seat opposite to the pull wire sensor, and a first spring is arranged between two adjacent limit seats.

[0007] Preferably, the connections between the first rigid baffle plate, the second rigid baffle plate, the first elastic baffle plate, the second elastic baffle plate and the base are treated with wax to make them water-tight, inner grooves are provided on both sides of the first elastic baffle plate and the second elastic baffle plate, both ends of the first rigid baffle plate and the second rigid baffle plate are located in the inner grooves, the middle parts of the first elastic baffle plate and the second elastic baffle plate are accordion-shaped, and the base, the first rigid baffle plate, the second rigid baffle plate, the first elastic baffle plate, the second elastic baffle plate, the limit seat and the side seat are all made of carbon fiber materials.

[0008] Preferably, a water outlet is provided on the surface of the first rigid baffle plate, the water outlet is close to the bottom of the first rigid baffle plate, and a water inlet is provided on the surface of the second rigid baffle plate, the water inlet is close to the top of the second rigid baffle plate, the horizontal height of the water outlet is lower than the horizontal height of the water inlet, and flanges are provided at the water outlet and the water inlet.

[0009] Preferably, a slot is provided on the surface of the side seat, a lower extension plate is fixed on the lower surface of the side seat, a locking hole is provided on the surface of the lower extension plate, a bottom plate is fixed to the bottom of the limit seat, the bottom plate is inserted into the slot, the bottom plate extends to the bottom of the side seat, a limit hole is provided on the surface of the bottom plate, threaded rods are screwed in the limit hole and the lock hole, and the four groups of limit seats are at the same horizontal position.

[0010] Preferably, the first spring is arranged at the periphery of the pull-wire sensor, one end of the first spring is fixedly connected to the limit seat where the pull-wire sensor is located, and the other end of the first spring is fixedly connected to another limit seat opposite to the stretching sensor.

[0011] Preferably, outer plates are provided on both sides of the first elastic baffle plate and the second elastic baffle plate, and a plurality of connecting rods are equidistantly fixed on the outer plates. The connecting rods are slidingly connected to the first elastic baffle plate and the second elastic baffle plate, and the other end of the connecting rods is fixedly connected to a resist plate, which is located in the inner groove, and the resist plate contacts and presses against the surfaces of the first rigid baffle plate and the second rigid baffle plate. A second spring is sleeved on the connecting rod, and the second spring is located between the outer plate and the elastic baffle plate, one end of the second spring is fixedly connected to the outer plate, and the other end of the second spring is fixedly connected to the surface of the elastic baffle plate, and when the second spring is not subjected to force, the resist plate does not contact the inner wall of the inner groove.

[0012] Preferably, the test box is arranged on a carrying platform, and the carrying platform is fixed on the processing platform. Vertical frames are fixed at the four ends of the surface of the carrying platform, and the vertical frames are in an "L" shape. Vertical grooves are opened at the four ends of the surface of the base, and the cross-section of the vertical groove is in an "L" shape. The outer wall of the vertical frame and the inner wall of the vertical groove are slidably connected, and hanging ears are fixed at both ends of both sides of the carrying platform, and hanging holes are opened on the surface of the hanging ears.

[0013] Preferably, support seats are fixed at the four ends of the bottom of the processing table, and the bottom of the support seats is disc-shaped. A control box is arranged on the processing table, and the control box is located next to the supporting platform. A partition is fixed between the control box and the supporting platform, and the height of the partition is higher than the control box.

[0014] Preferably, four groups of guide pillars are fixed on the surface of the processing table, the four groups of guide pillars are located around the bearing platform, a top platform is fixed on the top of the four groups of guide pillars, a hydraulic cylinder is arranged on the top platform, the output end of the hydraulic cylinder passes through the top platform and is fixedly connected with a lifting seat, the lifting seat is in the shape of a square plate, the four ends of the lifting seat are respectively slidably connected to the four groups of guide pillars, a pressure block is arranged on the lower surface of the lifting seat, the pressure block is located directly above the test box, and the pressure block and the hydraulic cylinder are electrically connected to the control box.

[0015] The method of the rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device comprises the following steps:

[0016] S1: Sampling and processing: The underground rock mass obtained from the project site is processed into samples with the same size as the internal size of the test box;

[0017] S2: Sample loading: insert the first rigid baffle and the second rigid baffle into the inner groove respectively, load the rock sample into the test box, and install the limit seat on the side seat;

[0018] S3: Acquisition of initial crack distribution of the specimen: The initial crack distribution in the specimen is obtained by CT scanning, and a three-dimensional model of the crack distribution is established using three-dimensional reconstruction technology;

[0019] S4: Water injection: Inject water into the test chamber through the water inlet and keep the water pressure constant until water seeps out of the water outlet;

[0020] S5: Pre-compression fracturing: Place the test box on the bearing platform of the processing table, start the hydraulic cylinder, and the output end of the hydraulic cylinder drives the lifting seat and the pressure block to move downward to apply pressure to the rock sample until the rock sample is damaged. During this period, the lateral displacement of the sample in all directions during the loading process is measured by the wire sensor, and the parameters such as ring count, amplitude and energy are monitored by the acoustic emission system to infer the crack development law of the sample during the loading process. At the same time, the outlet flow rate Q is measured by the volumetric flowmeter;

[0021] S6: Obtaining the crack distribution of the sample after pre-compression fracturing: Obtain the crack distribution of the sample after pre-compression fracturing through CT scanning and establish a three-dimensional model of the crack distribution;

[0022] S7: Analysis of the evolution of water flow pattern in the cracks of the sample: The change of the flow pattern of water flow during the pressure bearing process is judged according to the Reynolds number calculation method applicable to the flow of fluid in the cracks:

[0023]

[0024] ρ-fluid density, v e - flow velocity in the fracture, b- fracture opening, μ- fluid viscosity;

[0025] The velocity of water in the fracture v e According to the outlet flow rate Q and the effective flow cross-sectional area of ​​the crack, the rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device are determined. The effective flow cross-sectional area is affected by the crack opening b and the crack width w. The formula is as follows:

[0026]

[0027] A=b*w#(three

[0028] Substituting formula (2) and (3) into (1), we get the formula for calculating the crack Reynolds number:

[0029]

[0030] During the pressure-bearing process of the rock sample, the water density ρ and water viscosity μ remain unchanged at room temperature and can be measured using a density meter and a rotational viscometer respectively; the pressure-bearing process is divided into n sections according to time, and the flow rate Q can be measured by the flow meter to measure the changes in each time period, which is recorded as Qi; according to the initial crack distribution of the sample and the crack distribution of the sample after pre-compression fracturing, the average values ​​of the crack width are set as w1 and w2 respectively, and the crack generation amount in each time period and its ratio to the total crack generation amount are calculated according to the crack generation situation inferred from the acoustic emission test in each time period. According to this ratio and the average change value of the crack width before and after the sample is pressurized (w2-w1), the specific crack width change average value wi of each time period is obtained. Based on this, the Reynolds number of each time period can be calculated in real time according to formula (IV), see formula (V), and then the evolution law of the water flow state in the crack during the pre-compression fracturing process of the sample is deduced;

[0031]

[0032] S8: Grouting: Arrange grouting holes from above the pre-fracturing specimen, such as Fig.10 As shown, the grouting pump is first used to grout the middle grouting hole, and the end condition is determined according to the provisions of the "Grouting Technical Specification" (YS / T5211-2018) on the curtain grouting end standard: "When the top-down grouting method is adopted, the grouting section is under the maximum design pressure, and the flow rate is not more than 1L / min. After that, the grouting can be ended after continuing for 60 minutes." Then, the other grouting holes are grouted in turn according to the same standard. During the grouting process, the water flow rate of the outlet is monitored in real time;

[0033] S9: Obtaining the crack distribution of the sample after grouting: Obtain the crack distribution of the sample after grouting through CT scanning and establish a three-dimensional model of crack distribution, and compare the crack distribution after three CT scans;

[0034] S10: Slicing: Take out the sample after grouting, and slice it in horizontal and vertical directions from the middle part of the sample after grouting. Through the horizontal sample slicing, the horizontal diffusion distribution law of the slurry in the sample cracks can be observed, and through the vertical sample slicing, the vertical diffusion distribution law of the slurry in the sample cracks can be observed.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The invention proposes a rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device and method. The device can simulate the random crack generation of underground rock mass that maintains integrity after pressure-bearing crushing and expansion, and is closer to the distribution of actual rock mass cracks. Combined with grouting experiments and CT scanning technology, the diffusion law of slurry can be deeply studied to provide theoretical guidance for grouting reinforcement projects. Through monitoring means such as wire sensors, acoustic emission systems and volumetric flow meters, various parameters of the sample in the pre-compression fracturing process can be accurately measured and analyzed. The device has a simple structure, is easy to operate, and is easy to implement in the laboratory. It can be widely used in research and experimental teaching in the field of rock engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the structure of the test box of the present invention;

[0038] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0039] Figure 3 It is the front view of the overall structure of the present invention;

[0040] Figure 4 It is a schematic diagram of the structure of the carrier platform of the present invention;

[0041] Figure 5 This is a schematic diagram of the structure of the first elastic baffle of the present invention;

[0042] Figure 6 It is a side view of the test box structure of the present invention;

[0043] Figure 7 This is a schematic diagram of the base structure of the present invention;

[0044] Figure 8 This is a schematic diagram of the abutment plate structure of the present invention;

[0045] Fig. 9 It is a schematic diagram of the side seat structure of the present invention;

[0046] Fig.10It is a schematic diagram of the rock sample structure during grouting of the present invention.

[0047] In the figure: 1. hydraulic cylinder; 2. top platform; 3. lifting seat; 5. pressure block; 6. test box; 7. processing table; 8. bearing platform; 9. support seat; 10. control box; 11. partition; 12. guide column; 13. stand; 14. first rigid baffle; 15. first elastic baffle; 16. limit seat; 17. side seat; 18. vertical groove; 19. first spring; 20. base; 21. abutment plate; 22. water inlet; 23. flange; 24. hanging ear; 25. hanging hole; 26. wire sensor; 27. outer plate; 28. second rigid baffle; 29. ​​second elastic baffle; 30. water outlet; 32. inner groove; 34. slot; 36. connecting rod; 37. second spring; 38. bottom plate; 39. limit hole; 40. lower extension plate; 41. lock hole; 42. threaded rod. DETAILED DESCRIPTION

[0048] For the purpose of simplicity and illustration, the principles of the embodiments are mainly described by reference to examples. In the following description, many specific details are proposed to provide a thorough understanding of the embodiments. However, it is obvious that for those of ordinary skill in the art, these embodiments may not be limited to these specific details in practice. In some instances, known methods and structures are not described in detail to avoid making these embodiments unnecessarily difficult to understand. In addition, all embodiments can be used in combination with each other.

[0049] Example 1: Please refer to Figures 1 to 10 The present invention provides a technical solution: a rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device, comprising: a test box 6, the test box 6 comprises a base 20, a first rigid baffle 14, a second rigid baffle 28, a first elastic baffle 15, a second elastic baffle 29, a limit seat 16 and a side seat 17, the first rigid baffle 14, the second rigid baffle 28, the first elastic baffle 15 and the second elastic baffle 29 are all arranged on the base 20;

[0050] Side seats 17 are fixed on both sides of the first rigid baffle 14 and the second rigid baffle 28, and a limit seat 16 is arranged on the side seat 17. A pull-wire sensor 26 is arranged on one side surface of the limit seat 16, and the pull wire of the pull-wire sensor 26 is connected to another limit seat 16 opposite to the pull-wire sensor 26. A first spring 19 is arranged between two groups of adjacent limit seats 16. A rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device and method, including the rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device;

[0051] When in use, the device can simulate real cracks and study the slurry diffusion law of grouting reinforcement. By applying pressure to the rock sample inside the test box 6 through the hydraulic cylinder 1, random cracks can be generated, which is more in line with the actual situation.

[0052] Embodiment 2: On the basis of embodiment 1, the connection between the first rigid baffle 14, the second rigid baffle 28, the first elastic baffle 15, the second elastic baffle 29 and the base 20 is treated with wax coating and watertightness, and both sides of the first elastic baffle 15 and the second elastic baffle 29 are provided with inner grooves 32, and both ends of the first rigid baffle 14 and the second rigid baffle 28 are located in the inner grooves 32. The middle part of the first elastic baffle 15 and the second elastic baffle 29 is accordion-shaped, and the base 20, the first rigid baffle 14, the second rigid baffle 28, the first elastic baffle 15, the second elastic baffle 29, the limit seat 16 and the side seat 17 are all made of carbon fiber materials. When in use, in order to prevent the influence of structural materials on CT scanning results, carbon fiber materials are preferably used. The middle part of the elastic baffle is an accordion-shaped, freely expandable and retractable design, so that the sample has displacement space in the left and right directions during the pressure-bearing process. Wax coating and watertightness treatment are performed at the connection to prevent water leakage and ensure the accuracy of the experimental results.

[0053] A water outlet 30 is provided on the surface of the first rigid baffle plate 14, and the water outlet 30 is close to the bottom of the first rigid baffle plate 14. A water inlet 22 is provided on the surface of the second rigid baffle plate 28, and the water inlet 22 is close to the top of the second rigid baffle plate 28. The horizontal height of the water outlet 30 is lower than the horizontal height of the water inlet 22. Flanges 23 are provided at the water outlet 30 and the water inlet 22. When in use, by connecting a pipeline to the water inlet 22 and the water outlet 30, it is convenient to continuously supply water to the inside of the test box 6. The flange 23 is provided to facilitate the pipeline connection operation. At the same time, the water inlet 22 and the water outlet 30 are located one above the other, forming a height difference so that water can flow smoothly in the gap of the sample.

[0054] Embodiment 3: On the basis of embodiment 2, a slot 34 is provided on the surface of the side seat 17, a lower extension plate 40 is fixed on the lower surface of the side seat 17, a locking hole 41 is provided on the surface of the lower extension plate 40, a bottom plate 38 is fixed on the bottom of the limit seat 16, the bottom plate 38 is inserted into the slot 34, the bottom plate 38 extends to the bottom of the side seat 17, a limit hole 39 is provided on the surface of the bottom plate 38, a threaded rod 42 is screwed in the limit hole 39 and the locking hole 41, the four groups of limit seats 16 are in the same horizontal position, when in use, the bottom plates 38 are correspondingly inserted into the slots 34, the bottom plates 38 will extend to the bottom of the side seat 17, at this time the limit hole 39 and the locking hole 41 correspond, at this time the threaded rod 42 is screwed and locked into the inside of the two holes, so as to realize the limit installation of the limit seat 16;

[0055] The first spring 19 is arranged at the periphery of the pull-wire sensor 26, one end of the first spring 19 is fixedly connected to the limit seat 16 where the pull-wire sensor is located, and the other end of the first spring 19 is fixedly connected to another limit seat 16 opposite to the stretching sensor. When in use, the first spring 19 is used to tighten the limiter, and together with the limit seat 16, limit the inertial displacement of the baffle caused by the pressure and expansion of the sample, thereby ensuring that the displacement measured by the pull-wire sensor 26 is all caused by the lateral expansion of the sample.

[0056] Embodiment 4: On the basis of embodiment 3, both sides of the first elastic baffle 15 and the second elastic baffle 29 are provided with an outer plate 27, and a plurality of connecting rods 36 are fixed on the outer plate 27 at equal intervals. The connecting rod 36 is slidably connected to the first elastic baffle 15 and the second elastic baffle 29, and the other end of the connecting rod 36 is fixedly connected to the abutment plate 21, which is located in the inner groove 32. The abutment plate 21 and the first rigid baffle 14 and the second rigid baffle 28 are in contact and pressed against the surface, and a second spring 37 is sleeved on the connecting rod 36. The second spring 37 is located between the outer plate 27 and the elastic baffle, one end of the second spring 37 is fixedly connected to the outer plate 27, and the other end of the second spring 37 is fixedly connected to the surface of the elastic baffle. When the second spring 37 is not subjected to force, the butt plate 21 and the inner wall of the inner groove 32 do not contact each other. When in use, when the test rock is placed in the test box 6, the butt plate 21 will contact the surface of the test rock, and at the same time, the butt plate 21 and the inner wall of the inner groove 32 do not contact each other, so that after the test rock is compressed and expanded, the butt plate 21 will move, thereby realizing the movement of the test rock;

[0057] The test box 6 is arranged on the bearing platform 8, and the bearing platform 8 is fixed on the processing platform 7. The four ends of the surface of the bearing platform 8 are fixed with upright frames 13, and the upright frames 13 are in an "L" shape. The four ends of the surface of the base 20 are provided with upright grooves 18, and the cross section of the upright grooves 18 is in an "L" shape. The outer wall of the upright frame 13 and the inner wall of the upright groove 18 are slidably connected. The two ends of both sides of the bearing platform 8 are fixed with hanging ears 24, and the surface of the hanging ears 24 is provided with hanging holes 25. When in use, the bearing platform 8 is used to place the test box 6, and the processing platform 7 is used to install the control box 10, the hydraulic cylinder 1 and other equipment to provide necessary support and conditions for the experiment. When the base 20 is installed, the four sets of upright frames 13 are correspondingly slid into the upright grooves 18. The upright frames 13 and the upright grooves 18 are both in an "L" shape, which provide a limit for the base 20 to ensure the stability of the test box 6 during the test.

[0058] Support seats 9 are fixed at the four ends of the bottom of the processing table 7. The bottom of the support seat 9 is disc-shaped. A control box 10 is arranged on the processing table 7. The control box 10 is located next to the bearing platform 8. A partition 11 is fixed between the control box 10 and the bearing platform 8. The height of the partition 11 is higher than the control box 10. Four groups of guide pillars 12 are fixed on the surface of the processing table 7. The four groups of guide pillars 12 are located around the bearing platform 8. A top platform 2 is fixed on the top of the four groups of guide pillars 12. A hydraulic cylinder 1 is arranged on the top platform 2. The output end of the hydraulic cylinder 1 passes through the top platform 2 and is fixedly connected with a lifting seat 3. The lifting seat 3 is in the shape of a square plate. The four ends of the lifting seat 3 are respectively slidably connected with the four groups of guide pillars 12. A pressure block 5 is arranged on the lower surface of the lifting seat 3. The pressure block 5 is located just above the test box 6. The pressure block 5 and the hydraulic cylinder 1 are both electrically connected to the control box 10.

[0059] When in use, the control box 10 is used to control the start and stop of the hydraulic cylinder 1 to realize the automated control of the experiment. The hydraulic cylinder 1 can accurately control the pressure of the pressure block 5 on the rock sample to ensure the accuracy of the experimental results.

[0060] Working principle: In actual use, this device can simulate the random crack generation of underground rock mass that maintains integrity after pressure expansion, which is closer to the distribution of actual rock mass cracks. Combined with grouting test and CT scanning technology, it can deeply study the diffusion law of slurry and provide theoretical guidance for grouting reinforcement engineering. Through monitoring means such as wire sensor 26, acoustic emission system and volumetric flow meter, it can accurately measure and analyze various parameters of the sample in the pre-compression fracturing process. The device has a simple structure, convenient operation, and is easy to implement in the laboratory. It can be widely used in research and experimental teaching in the field of rock engineering.

[0061] The method of the rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device comprises the following steps:

[0062] S1: Sampling and processing: Process the underground rock mass obtained from the project site into samples with the same internal dimensions as the test box 6;

[0063] S2: Sample loading: insert the first rigid baffle (14) and the second rigid baffle 28 into the inner groove 32 accordingly, load the rock sample into the test box 6, and install the limit seat 16 on the side seat 17;

[0064] S3: Acquisition of initial crack distribution of the specimen: The initial crack distribution in the specimen is obtained by CT scanning, and a three-dimensional model of the crack distribution is established using three-dimensional reconstruction technology;

[0065] S4: water injection: water is injected into the test box 6 through the water inlet 22, and the water pressure is kept constant until water seeps out of the water outlet (30);

[0066] S5: Pre-compression fracturing: the test box 6 is placed on the bearing platform 8 of the processing table 7, and the hydraulic cylinder 1 is started. The output end of the hydraulic cylinder 6 drives the lifting seat 3 and the pressure block 5 to move downward to apply pressure to the rock sample until the rock sample is damaged. During this period, the lateral displacement of the sample in all directions during the loading process is measured by the wire sensor (26), and the parameters such as ring count, amplitude and energy are monitored by the acoustic emission system to infer the crack development law of the sample during the loading process. At the same time, the outlet flow rate Q is measured by the volumetric flow meter;

[0067] S6: Obtaining the crack distribution of the sample after pre-compression fracturing: Obtain the crack distribution of the sample after pre-compression fracturing through CT scanning and establish a three-dimensional model of the crack distribution;

[0068] S7: Analysis of the evolution of water flow pattern in the cracks of the sample: The change of the flow pattern of water flow during the pressure bearing process is judged according to the Reynolds number calculation method applicable to the flow of fluid in the cracks:

[0069]

[0070] ρ-fluid density, v e - flow velocity in the fracture, b- fracture opening, μ- fluid viscosity;

[0071] The velocity of water in the fracture v e It is determined according to the outlet flow rate Q and the effective flow cross-sectional area A of the crack. The effective flow cross-sectional area is affected by the crack opening b and the crack width w. The formula is as follows:

[0072]

[0073] A=b*w#(three

[0074] Substituting formula (2) and (3) into (1), we get the formula for calculating the crack Reynolds number:

[0075]

[0076] During the pressure-bearing process of the rock sample, the water density ρ and water viscosity μ remain unchanged at room temperature and can be measured using a density meter and a rotational viscometer respectively; the pressure-bearing process is divided into n sections according to time, and the flow rate Q can be measured by the flow meter to measure the changes in each time period, which is recorded as Qi; according to the initial crack distribution of the sample and the crack distribution of the sample after pre-compression fracturing, the average values ​​of the crack width are set as w1 and w2 respectively, and the crack generation amount in each time period and its ratio to the total crack generation amount are calculated according to the crack generation situation inferred from the acoustic emission test in each time period. According to this ratio and the average change value of the crack width before and after the sample is pressurized (w2-w1), the specific crack width change average value wi of each time period is obtained. Based on this, the Reynolds number of each time period can be calculated in real time according to formula (IV), see formula (V), and then the evolution law of the water flow state in the crack during the pre-compression fracturing process of the sample is deduced;

[0077]

[0078] S8: Grouting: Arrange grouting holes from above the pre-fracturing specimen, such as Fig.10 As shown, the grouting pump is first used to grout the middle grouting hole, and the end condition is determined according to the provisions of the "Grouting Technical Specification" (YS / T5211-2018) on the curtain grouting end standard: "When the top-down grouting method is adopted, the grouting section is under the maximum design pressure, and the flow rate is not more than 1L / min. After that, the grouting can be ended after continuing for 60 minutes." Then, the other grouting holes are grouted in turn according to the same standard. During the grouting process, the water flow rate of the outlet is monitored in real time;

[0079] S9: Obtaining the crack distribution of the sample after grouting: Obtain the crack distribution of the sample after grouting through CT scanning and establish a three-dimensional model of crack distribution, and compare the crack distribution after three CT scans;

[0080] S10: Slicing: Take out the sample after grouting, and slice it in horizontal and vertical directions from the middle part of the sample after grouting. Through the horizontal sample slicing, the horizontal diffusion distribution law of the slurry in the sample cracks can be observed, and through the vertical sample slicing, the vertical diffusion distribution law of the slurry in the sample cracks can be observed.

[0081] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Experimental device for distribution of pre-compression cracks in rock blocks and diffusion of grouting reinforcement slurry, characterized by: The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device comprises: a test box (6), the test box (6) comprises a base (20), a first rigid baffle (14), a second rigid baffle (28), a first elastic baffle (15), a second elastic baffle (29), a limit seat (16) and a side seat (17), the first rigid baffle (14), the second rigid baffle (28), the first elastic baffle (15) and the second elastic baffle (29) are all arranged on the base (20); Side seats (17) are fixed on both sides of the first rigid baffle plate (14) and the second rigid baffle plate (28); a limit seat (16) is arranged on the side seat (17); a pull wire sensor (26) is arranged on one side surface of the limit seat (16); a pull wire of the pull wire sensor (26) is connected to another limit seat (16) on the opposite side of the pull wire sensor (26); and a first spring (19) is arranged between two groups of adjacent limit seats (16).

2. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 1 is characterized by: The connection between the first rigid baffle plate (14), the second rigid baffle plate (28), the first elastic baffle plate (15), the second elastic baffle plate (29) and the base (20) is treated with wax coating to achieve water-tightness. Both sides of the first elastic baffle plate (15) and the second elastic baffle plate (29) are provided with inner grooves (32). Both ends of the first rigid baffle plate (14) and the second rigid baffle plate (28) are located in the inner grooves (32). The middle parts of the first elastic baffle plate (15) and the second elastic baffle plate (29) are accordion-shaped. The base (20), the first rigid baffle plate (14), the second rigid baffle plate (28), the first elastic baffle plate (15), the second elastic baffle plate (29), the limit seat (16) and the side seat (17) are all made of carbon fiber materials.

3. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 1 is characterized by: A water outlet (30) is provided on the surface of the first rigid baffle (14), and the water outlet (30) is close to the bottom of the first rigid baffle (14); a water inlet (22) is provided on the surface of the second rigid baffle (28), and the water inlet (22) is close to the top of the second rigid baffle (28); the horizontal height of the water outlet (30) is lower than the horizontal height of the water inlet (22); and flanges (23) are provided at the water outlet (30) and the water inlet (22).

4. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 1 is characterized by: The surface of the side seat (17) is provided with a slot (34), the lower surface of the side seat (17) is fixed with a lower extension plate (40), the surface of the lower extension plate (40) is provided with a locking hole (41), the bottom of the limiting seat (16) is fixed with a bottom plate (38), the bottom plate (38) is inserted into the slot (34), the bottom plate (38) extends to the bottom of the side seat (17), the surface of the bottom plate (38) is provided with a limiting hole (39), the limiting hole (39) and the locking hole (41) are screwed with a threaded rod (42), and the four groups of limiting seats (16) are at the same horizontal position.

5. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 1 is characterized by: The first spring (19) is arranged at the periphery of the pull-wire sensor (26), one end of the first spring (19) is fixedly connected to a limit seat (16) where the pull-wire sensor is located, and the other end of the first spring (19) is fixedly connected to another limit seat (16) opposite to the stretch sensor.

6. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 1 is characterized by: Both sides of the first elastic baffle (15) and the second elastic baffle (29) are provided with outer plates (27), and a plurality of connecting rods (36) are fixed on the outer plate (27) at equal intervals. The connecting rods (36) are slidably connected to the first elastic baffle (15) and the second elastic baffle (29), and the other end of the connecting rod (36) is fixedly connected to a resisting plate (21), and the resisting plate (21) is located in the inner groove (32). The resisting plate (21) and the first rigid baffle (14) and the second rigid baffle (28) are in contact and pressed against each other on the surface. A second spring (37) is sleeved on the connecting rod (36), and the second spring (37) is located between the outer plate (27) and the elastic baffle, and one end of the second spring (37) is fixedly connected to the outer plate (27), and the other end of the second spring (37) is fixedly connected to the surface of the elastic baffle. When the second spring (37) is not subjected to force, the resisting plate (21) and the inner wall of the inner groove (32) do not contact.

7. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 1 is characterized by: The test box (6) is arranged on a bearing platform (8), and the bearing platform (8) is fixed on a processing platform (7). Stands (13) are fixed at the four ends of the surface of the bearing platform (8), and the stand (13) is in an "L" shape. Stands (18) are provided at the four ends of the surface of the base (20), and the cross section of the stand (18) is in an "L" shape. The outer wall of the stand (13) and the inner wall of the stand (18) are slidably connected. Hanging ears (24) are fixed at both ends of the two sides of the bearing platform (8), and the surface of the hanging ears (24) is provided with hanging holes (25).

8. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 7, characterized in that: Support seats (9) are fixed at the four ends of the bottom of the processing table (7), and the bottom of the support seat (9) is disc-shaped. A control box (10) is arranged on the processing table (7), and the control box (10) is located next to the bearing platform (8). A partition (11) is fixed between the control box (10) and the bearing platform (8), and the height of the partition (11) is higher than that of the control box (10).

9. The rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to claim 8, characterized in that: Four groups of guide columns (12) are fixed on the surface of the processing table (7), and the four groups of guide columns (12) are located around the bearing platform (8). A top platform (2) is fixed on the top of the four groups of guide columns (12), and a hydraulic cylinder (1) is arranged on the top platform (2). The output end of the hydraulic cylinder (1) passes through the top platform (2) and is fixedly connected to a lifting seat (3). The lifting seat (3) is in the shape of a square plate. The four ends of the lifting seat (3) are respectively slidably connected to the four groups of guide columns (12). A pressure block (5) is arranged on the lower surface of the lifting seat (3), and the pressure block (5) is located directly above the test box (6). The pressure block (5) and the hydraulic cylinder (1) are both electrically connected to the control box (10).

10. A method for the rock block pre-compression crack distribution and grouting reinforcement slurry diffusion experimental device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: Sampling and processing: The underground rock mass obtained from the project site is processed into a sample with the same internal size as the test box (6); S2: Sample loading: insert the first rigid baffle (14) and the second rigid baffle (28) into the inner groove (32) respectively, load the rock sample into the test box (6), and install the limit seat (16) on the side seat (17); S3: Acquisition of initial crack distribution of the specimen: The initial crack distribution in the specimen is obtained by CT scanning, and a three-dimensional model of the crack distribution is established using three-dimensional reconstruction technology; S4: Water injection: water is injected into the test box (6) through the water inlet (22) and the water pressure is kept constant until water seeps out of the water outlet (30); S5: Pre-compression fracturing: the test box (6) is placed on the bearing platform (8) of the processing platform (7), and the hydraulic cylinder (1) is started. The output end of the hydraulic cylinder (6) drives the lifting seat (3) and the pressure block (5) to move downward, thereby applying pressure to the rock sample until the rock sample is destroyed. During this period, the lateral displacement of the sample in all directions during the loading process is measured by the wire sensor (26), and the parameters such as ring count, amplitude and energy are monitored by the acoustic emission system to infer the crack development law of the sample during the loading process. At the same time, the outlet flow rate Q is measured by the volumetric flow meter; S6: Obtaining the crack distribution of the sample after pre-compression fracturing: Obtain the crack distribution of the sample after pre-compression fracturing through CT scanning and establish a three-dimensional model of the crack distribution; S7: Analysis of the evolution of water flow pattern in the cracks of the sample: The change of the flow pattern of water flow during the pressure bearing process is judged according to the Reynolds number calculation method applicable to the flow of fluid in the cracks: ρ-fluid density, v e - flow velocity in the fracture, b- fracture opening, μ- fluid viscosity; The velocity of water in the fracture v e It is determined according to the outlet flow rate Q and the effective flow cross-sectional area A of the crack. The effective flow cross-sectional area is affected by the crack opening b and the crack width w. The formula is as follows: A=b*w# ( three) Substituting formula (2) and (3) into (1), we get the formula for calculating the crack Reynolds number: During the pressure-bearing process of the rock sample, the water density ρ and water viscosity μ remain unchanged at room temperature and can be measured using a density meter and a rotational viscometer respectively; the pressure-bearing process is divided into n sections according to time, and the flow rate Q can be measured by the flow meter to measure the changes in each time period, which is recorded as Qi; according to the initial crack distribution of the sample and the crack distribution of the sample after pre-compression fracturing, the average values ​​of the crack width are set as w1 and w2 respectively, and the crack generation amount in each time period and its ratio to the total crack generation amount are calculated according to the crack generation situation inferred from the acoustic emission test in each time period. According to this ratio and the average change value of the crack width before and after the sample is pressurized (w2-w1), the specific crack width change average value wi of each time period is obtained. Based on this, the Reynolds number of each time period can be calculated in real time according to formula (IV), see formula (V), and then the evolution law of the water flow state in the crack during the pre-compression fracturing process of the sample is deduced; S8: Grouting: Arrange grouting holes from the top of the sample after pre-fracturing, as shown in Figure 10. First, use a grouting pump to grout the middle grouting hole, and determine the end condition according to the provisions of the "Grouting Technical Specification" (YS / T5211-2018) on the end standard of curtain grouting: "When the top-down grouting method is adopted, the grouting section is under the maximum design pressure, and the flow rate is not more than 1L / min. After that, continue grouting for 60 minutes, and the grouting can be ended." Then grouting is carried out in turn for other grouting holes according to the same standard. During the grouting process, the water flow rate of the outlet is monitored in real time; S9: Obtaining the crack distribution of the sample after grouting: Obtain the crack distribution of the sample after grouting through CT scanning and establish a three-dimensional model of crack distribution, and compare the crack distribution after three CT scans; S10: Slicing: Take out the sample after grouting, and slice it in horizontal and vertical directions from the middle part of the sample after grouting. Through the horizontal sample slicing, the horizontal diffusion distribution law of the slurry in the sample cracks can be observed, and through the vertical sample slicing, the vertical diffusion distribution law of the slurry in the sample cracks can be observed.

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