Testing device for blocking rock fractures through calcium carbonate deposition induced by soybean urease

Abstract

The utility model discloses a test device for blocking rock fractures by soybean urease induced calcium carbonate deposition, which comprises a sample, a fracture simulation component and a slurry sealing component, and the sample consists of an upper rock test block and a lower rock test block; the fracture simulation assembly can simulate two kinds of rock fracture surfaces with different opening degrees. The test sample adopts an upper rock test block made of a transparent material to realize visualization in a test process; the upper shear box and the lower shear box are used for simulating a tension type fracture and a shear fracture surface of a rock, so that the condition that soybean urease induces calcium carbonate to deposit in different rock fracture generation mechanisms to block and reduce permeability of the rock fracture is better tested; when the lower shear box horizontally moves, the lower shear box is sealed through the slurry sealing assembly, and the sealing state can be kept in the shear dislocation of the crack; the device can test the relationship between the soybean urease induced calcium carbonate deposition plugging and permeation reducing effect and the rock fracture type and fracture parameters.

Description

Technical Field

[0001] The utility model relates to the technical field of underground engineering, and particularly relates to a test device for plugging rock fractures by soybean urease-induced calcium carbonate precipitation. Background Art

[0002] There are different types, different apertures and roughnesses of rock fractures inside rock masses. The existence of these fractures reduces the strength of the rock mass and at the same time increases the permeability of the rock mass, bringing potential safety hazards to underground rock engineering. In underground rock engineering, cement slurry is usually used to plug rock fractures in order to reduce the fracture permeability and thus enhance the strength of the rock mass. However, cement slurry is an alkaline material, which causes great environmental pollution, and the viscosity of cement slurry is relatively large, so it cannot penetrate into rock fractures with small apertures, and its anti-seepage effect is greatly affected by the rock fracture environment. As a new type of reinforcement and anti-seepage technology, the soybean urease-induced calcium carbonate precipitation (SICP) technology has great application prospects in plugging rock fractures. By injecting a cementing solution (urea and CaCl2 solution) and a urease solution into the rock fractures, calcium carbonate crystals will be generated inside the rock fractures, so as to achieve the purpose of strengthening the rock fractures and reducing the fracture permeability. Moreover, the SICP slurry has strong permeability, can be applied to rock fractures of different scales and types, and is environmentally friendly.

[0003] In underground rock engineering, the scales of rock fractures are different, the apertures and roughnesses are different, and the generation mechanisms of rock fractures are also different, which are mainly divided into tensile fractures or shear fractures. The reinforcement and anti-seepage effects of the SICP grouting technology on rock fractures are closely related to the rock fracture parameters (aperture, roughness) and fracture types. However, at present, the test devices and test methods for SICP grouting for different rock fracture types and fracture parameters are relatively lacking. Summary of the Utility Model

[0004] Aiming at the defects existing in the above-mentioned prior art, the technical problem to be solved by the utility model is to provide a test device for plugging rock fractures by soybean urease-induced calcium carbonate precipitation, which can visually and visually observe the plugging and seepage reduction of rock fractures by soybean urease-induced calcium carbonate precipitation, and can simulate the fracture apertures in two cases of tensile fractures or shear fractures of rock blocks.

[0005] In order to solve the above technical problems, the utility model adopts the following technical scheme: A test device for plugging rock fractures by soybean urease-induced calcium carbonate precipitation, comprising a specimen, a fracture simulation assembly and a slurry sealing assembly. The specimen is composed of a matching upper rock test block and a lower rock test block, and the upper rock test block is made of a transparent material;

[0006] The crack simulation assembly includes an upper shear box, a lower shear box and a base. The upper shear box is used to clamp the upper rock test block, and the lower shear box is used to hold the lower rock test block. When the upper shear box and the lower shear box are respectively installed at the upper and lower parts of the specimen, there is a gap between them. The base is provided with a vertical support rod and a horizontal rolling groove, and both the vertical support rod and the horizontal rolling groove are marked with scales. The upper shear box is slidably connected to the vertical support rod, so that the upper rock test block can move up and down relative to the lower rock test block to simulate the tensile crack of the rock mass. The lower shear box can roll on the horizontal rolling groove, so that the lower rock test block can move left and right relative to the upper rock test block to simulate the shear crack of the rock mass.

[0007] The slurry sealing assembly includes a pair of end flow guiding blocks, end water sealing pressure plates, end water sealing rubber pads, side water sealing rubber pads and side water sealing pressure plates. A fluid channel is provided inside the end flow guiding blocks, and they are fixedly installed at the left and right ends of the specimen. The end water sealing rubber pads are arranged between the end flow guiding blocks and the end water sealing pressure plates. Both the end flow guiding blocks and the end water sealing pressure plates adopt a split structure corresponding to the upper shear box and the lower shear box. The end water sealing rubber pads adopt an integral structure and have a redundant amount bulging outwards at the upper and lower split positions. The side water sealing rubber pads and the side water sealing pressure plates are both arranged on the front and back sides of the specimen to seal the gap between the upper shear box and the lower shear box. Extension amounts are provided at the left and right ends of the side water sealing rubber pads and the side water sealing pressure plates, so as to ensure that when the lower shear box moves left and right relative to the upper shear box to the extreme position, it can still be flexibly lapped with both ends of the end water sealing rubber pad to form a sealed storage cavity.

[0008] Preferably, the upper rock test block is cast from a transparent resin material, and the lower rock test block is made of real rock material.

[0009] Preferably, the upper shear box tightly clamps and fixes the upper rock test block through a tightening bolt a. A rectangular observation port is provided at the top of the upper shear box to cooperate with the transparent upper rock test block, so as to realize the visual observation of the slurry flow and calcium carbonate deposition inside the crack surface. The upper shear box is slidably connected to the vertical support rod through a horizontal connecting rod with a sleeve at the end, and is fixed by tightening the tightening bolt b arranged in the sleeve. Four vertical support rods corresponding to the upper shear box are provided, so that the movement of the upper shear box is accurate and stable.

[0010] Preferably, a roller is installed in the horizontal rolling groove to realize the horizontal movement of the lower shear box, and the horizontal movement of the lower shear box is realized through a hand-operated top push rod.

[0011] Preferably, the surface of the vertical support rod is marked with scales, and a horizontal scale is provided at the edge of the horizontal rolling groove.

[0012] Preferably, the side water sealing pressure plate is fixed and pressed through an "L"-shaped pressure plate support frame and fastening bolts, and the pressure plate support frame is fixed on the base through fixing bolts.

[0013] Preferably, the end water sealing rubber pad is made of industrial rubber plate, and the side water sealing rubber pad is made of silica gel material.

[0014] 1) The specimen is made of a transparent upper rock test block to realize visualization during the test, and further understand the process of sealing and reducing seepage of rock fissures by soybean urease-induced calcium carbonate deposition;

[0015] 2) By using the upper shear box and the lower shear box to simulate the tensile fissures and shear fissure surfaces of the rock, it is better to test the sealing and seepage reduction of soybean urease-induced calcium carbonate deposition in different rock fissure generation mechanisms;

[0016] 3) When the lower shear box moves horizontally, it is sealed through the slurry sealing assembly, and the sealing state can also be maintained during the shear dislocation of the fissure;

[0017] 4) This device can test the relationship between the sealing and seepage reduction effect of soybean urease-induced calcium carbonate deposition and the rock fissure type and fissure parameters, which is beneficial to the development of the technology of soybean urease-induced calcium carbonate deposition. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the shear structure of the present invention;

[0019] Figure 2 It is a schematic diagram of the grouting reinforcement and seepage reduction structure of the present invention;

[0020] Figure 3 is Figure 2 the top view of

[0021] Figure 4 It is a schematic diagram of the seepage test system;

[0022] Figure 5 It is a schematic diagram of the experiment of the present invention;

[0023] In the figure: 1 - specimen, 2 - upper shear box, 3 - horizontal connecting rod, 4 - fastening bolt a, 5 - vertical support rod, 6 - fastening bolt b, 7 - base, 8 - horizontal rolling groove, 9 - lower shear box, 10 - end flow guiding block, 11 - end water sealing pressure plate, 12 - end water sealing rubber pad, 13 - side water sealing rubber pad, 14 - side water sealing pressure plate, 15 - fastening bolt, 16 - pressure plate support frame, 17 - fixing bolt, 18 - hand-operated jacking push rod, 19 - horizontal scale, 20 - soybean urease solution, 21 - supernatant, 22 - cementing liquid, 23 - liquid pump, 24 - valve a, 25 - valve b, 26 - valve c, 27 - valve d, 28 - slurry recovery container, 29 - light source, 30 - high-speed camera, 31 - air compressor, 32 - pressure tank, 33 - water storage tank, 34 differential pressure gauge, 35 - flowmeter. Detailed implementation mode

[0024] In order to better understand the improvements made by the present invention compared with the prior art, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0025] As Figure 1 —shown in FIG. 3, a test device for soybean urease-induced calcium carbonate deposition to seal rock fractures mainly consists of a specimen 1, a fracture simulation assembly and a slurry sealing assembly. The specimen 1 is composed of a matching upper rock test block and a lower rock test block. The opposite surfaces of the upper rock test block and the lower rock test block are meshed with each other to simulate the rock fractures inside the natural rock mass. The upper rock test block is made of a transparent material convenient for observation, preferably cast from a transparent resin material, and the lower rock test block is made of real rock material.

[0026] The fracture simulation assembly mainly consists of an upper shear box 2, a lower shear box 9 and a base 7. The upper shear box 2 is used to clamp the upper rock test block, and the lower shear box 9 is used to hold the lower rock test block. When the upper shear box 2 and the lower shear box 9 are respectively installed on the upper and lower parts of the specimen 1, there is a gap between them to facilitate the relative movement between the upper shear box 2 and the lower shear box 9. The upper shear box 2 fixes the upper rock test block by means of a fastening bolt a 4. The top of the upper shear box 2 is provided with a rectangular observation port to cooperate with the transparent upper rock test block, so as to realize the visual observation of the slurry flow and calcium carbonate deposition inside the fracture surface.

[0027] The base 7 is provided with a vertical support rod 5 and a horizontal rolling groove 8, and both the vertical support rod 5 and the horizontal rolling groove 8 are provided with scales. Preferably, the surface of the vertical support rod 5 is marked with scales, and a horizontal scale 19 is provided at the edge of the horizontal rolling groove 8. The upper shear box 2 is slidably connected to the vertical support rod 5 through a horizontal connecting rod 3 with sleeves at both ends, and is fixed by tightening the fastening bolt b 6 arranged in the sleeve, so that the upper rock test block can move up and down relative to the lower rock test block to simulate the tensile crack of the rock block. Among them, four vertical support rods 5 corresponding to the upper shear box 2 are provided, so that the movement of the upper shear box 2 is accurate and stable. A roller is installed in the horizontal rolling groove 8. The roller has lower precision requirements compared with the ball, and the protection and replacement cost is low. The lower shear box 9 can roll on the horizontal rolling groove 8 through a hand-operated push rod 18, so that the lower rock test block can move left and right relative to the upper rock test block to simulate the shear crack of the rock block.

[0028] The slurry sealing assembly is mainly composed of paired end guide blocks 10, end water sealing pressure plates 11, end water sealing rubber pads 12, side water sealing rubber pads 13 and side water sealing pressure plates 14. A fluid channel is provided inside the end guide block 10 and is fixedly installed at the left and right ends of the specimen 1. The fluid channel is a right-angled fluid channel. The end water sealing rubber pad 12 is arranged between the end guide block 10 and the end water sealing pressure plate 11, and both the end guide block 10 and the end water sealing pressure plate 11 adopt a split structure corresponding to the upper shear box 2 and the lower shear box 9. The end water sealing rubber pad 12 adopts an integral structure and has a redundant amount bulging outwards at the upper and lower split positions.

[0029] The side water sealing rubber pad 13 and the side water sealing pressure plate 14 are both arranged on the front and back sides of the specimen 1 to seal the gap between the upper shear box 2 and the lower shear box 9. The side water sealing pressure plate 14 is preferably fixed and pressed through the "L"-shaped pressure plate support frame 16 and the fastening bolt 15. The pressure plate support frame 16 is fixed on the base 7 through the fixing bolt 17. Extension amounts are provided at both the left and right ends of the side water sealing rubber pad 13 and the side water sealing pressure plate 14 to ensure that when the lower shear box 9 moves relatively to the upper shear box 2 to the extreme position left and right, it can still be flexibly lapped with both ends of the end water sealing rubber pad 12 to form a sealed storage cavity. The end water sealing rubber pad 12 is preferably made of industrial rubber plate, with a thickness of 3 mm, flexible and fold-resistant, smooth surface, good sealing performance, acid and alkali resistant. The side water sealing rubber pad 13 is preferably made of silica gel material, which is softer than the end water sealing rubber pad 12. To ensure a better sealing effect, the thickness is 10 mm. Under the extrusion of the side water sealing pressure plate 14, the side of the crack can be fully sealed. And due to the large flexibility of the side water sealing rubber pad 13, when the rock crack is sheared, the side water sealing rubber pad 13 can still deform accordingly and maintain a good sealing property. At the same time, since the end water sealing rubber pad 12 has greater toughness and stiffness than the side water sealing rubber pad 13, under the extrusion of the side water sealing pressure plate 14, the boundary of the end water sealing rubber pad 12 can form a tight lap with the side water sealing rubber pad 13. This lap can also maintain a good sealing property along with the shear displacement of the crack.

[0030] The above-mentioned soybean urease-induced calcium carbonate deposition technology is adopted for testing with a rock testing device, including the following steps:

[0031] Step 1: Simulate the opening of tensile cracks. Install the specimen 1 on the crack simulation component, keep the upper rock test block and the lower rock test block in a natural meshing state, and consider the crack to be in the initial closed state at this time. Read the scale value h0 of the upper shear box 2 relative to the vertical support rod 5, and h0 is preferably the average value of the scale values of the four sleeves on the corresponding vertical support rod 5.

[0032] Keep the lower shear box 9 and the lower rock test block stationary, vertically lift the upper shear box 2 and the upper rock test block, and read the scale value h0' of the upper shear box 2 relative to the vertical support rod 5. Thus, a tensile rock crack with a crack opening of Δh = h0' - h0 can be obtained.

[0033] Step 2: Simulate the opening of shear cracks. Install the specimen 1 on the crack simulation component, keep the upper rock test block and the lower rock test block in a natural meshing state, and consider the crack to be in the initial closed state at this time. Read the scale value h0 of the upper shear box 2 relative to the vertical support rod 5, and read the horizontal scale value s0 of the horizontal rolling groove 8 corresponding to the left or right end edge of the lower shear box 9.

[0034] Gradually move the lower shear box and the lower rock block horizontally. Due to the roughness of the rock fracture surface, the horizontal displacement of the lower shear box 9 will also cause the vertical free movement of the upper shear box and the rock block. It is necessary to read the scale value h0' of the upper shear box 2 relative to the vertical support rod 5, and read the horizontal scale value s0' of the horizontal rolling groove 8 corresponding to the left or right end edge of the lower shear box 9. Thus, the shear displacement of the fracture is Δs = s0' - s0, and the aperture of the fracture is Δh = h0' - h0 for the shear-type rock fracture.

[0035] Step 3: First, test the permeability coefficient of the rock fracture before grouting reinforcement to form a control group. As Figure 4 shown, use a seepage test system to adjust the pressure value of the air compressor 31 so that the water in the pressure tank 32 flows into the rock fracture under a certain hydraulic pressure through the valve a24. At the initial injection, the valves a24, b25, c26, and d27 are all opened. When the water can flow into the water storage tank 33 through the valve b25 or c26, the corresponding valve b25 or c26 is closed; keep the valves a24 and d27 open, maintain a constant water pressure, and continue to inject water. After the reading of the flowmeter is stable, read the reading Q1 of the flowmeter 35 and the reading P1 of the differential pressure gauge 34. Adjust the pressure value of the air compressor 31 to adjust the reading of the differential pressure gauge 34 to P2, record the corresponding flowmeter reading Q2, and repeat the above steps to obtain at least three groups of differential pressure-flow data, and calculate the permeability coefficient of the current rock fracture based on this.

[0036] Step 4: As Figure 5 shown, carry out soybean urease-induced calcium carbonate deposition grouting reinforcement and seepage reduction for the above two different types of rock fractures. Obtain the soybean urease solution 20 by stirring soybeans, filter out the soybean dregs, and take the supernatant 21. Mix the calcium chloride solution with a concentration of 1.8 - 2.2 mol / L and the urea solution with a concentration of 1.8 - 2.2 mol / L in equal volume to prepare the cementing solution 22. The concentration of the calcium chloride solution and the urea solution is preferably both 2.0 mol / L. After mixing the cementing solution 22 and the urease solution 21, use the liquid pump 23 to inject it into the rock fracture at a constant rate through the valve 24.

[0037] During the initial injection, valves a24, b25, c26, and d27 are all opened. When the slurry can flow into the slurry recovery container 28 through valve b25 or valve c26, the corresponding valve b25 or valve c26 is closed. Continue to inject the slurry until the slurry can flow into the slurry recovery container 28 through valves a24 and d27, then valves a24 and d27 can be closed to stop the slurry injection, and keep valves a24, b25, c26, and d27 all closed, so that the slurry stands still in the cracks of specimen 1 for 8 - 14 hours, preferably 12 hours, to ensure that the slurry in the cracks fully reacts to generate calcium carbonate deposition, achieving the effect of cementing the rock fracture surface.

[0038] Step Five: After 8 - 14 hours, connect to the seepage test system, and slowly inject clear water into the cracks of specimen 1. Continuously inject to flush out the slurry in the rock cracks after the reaction. At this time, turn on the light source 29, and use a high-speed camera 30 to take pictures of the cemented rock fracture surface, and analyze the deposition pattern, crystal size, and cementation characteristics of calcium carbonate crystals in the cracks of specimen 1. Use the method in Step Three to test the permeability coefficient of the rock fracture surface after grouting with calcium carbonate deposition induced by soybean urease.

[0039] Step Six: Repeat Step One or Step Two, using rock fracture surfaces with different roughnesses, tensile rock fractures with different crack apertures, or shear rock fractures with different shear displacements and apertures, to analyze the relationship between the effect of calcium carbonate deposition induced by soybean urease grouting and the rock fracture type and fracture parameters. Repeat Step Four and Step Five to successively obtain the changes in the cementation position, size, and permeability coefficient of calcium carbonate crystals in the rock fracture surface after at least three groutings, so as to obtain the anti-seepage effect of calcium carbonate deposition induced by soybean urease on tensile or shear rock fractures.

[0040] As mentioned above, it is only the preferred specific implementation mode of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model, according to the technical solution of the present utility model and its inventive concept, makes equivalent replacements or changes, and all should be covered within the protection scope of the present utility model.

Claims

1. A test device for plugging rock fractures by inducing calcium carbonate deposition with soybean urease, characterized in that: It includes a specimen (1), a fracture simulation component, and a slurry sealing component. The specimen (1) is composed of a matching upper rock test block and a lower rock test block, and the upper rock test block is made of a transparent material. The fracture simulation component includes an upper shear box (2), a lower shear box (9), and a base (7). The upper shear box (2) is used to hold the upper rock test block, and the lower shear box (9) is used to hold the lower rock test block. When the upper shear box (2) and the lower shear box (9) are respectively installed on the upper and lower parts of the specimen (1), there is a gap between them. The base (7) is provided with a vertical support rod (5) and a horizontal rolling groove (8), and both the vertical support rod (5) and the horizontal rolling groove (8) are provided with scales. The upper shear box (2) is slidably connected to the vertical support rod (5) to enable the upper rock test block to move up and down relative to the lower rock test block to simulate the tensile fracture of the rock block, and the lower shear box (9) can roll on the horizontal rolling groove (8) to enable the lower rock test block to move left and right relative to the upper rock test block to simulate the shear fracture of the rock block. The slurry sealing component includes a pair of end guide blocks (10), end water sealing pressure plates (11), end water sealing rubber gaskets (12), side water sealing rubber gaskets (13), and side water sealing pressure plates (14). A fluid channel is provided inside the end guide block (10), and the end guide block (10) is fixedly installed at the left and right ends of the specimen (1). The end water sealing rubber gasket (12) is arranged between the end guide block (10) and the end water sealing pressure plate (11). The end guide block (10) and the end water sealing pressure plate (11) both adopt a split structure corresponding to the upper shear box (2) and the lower shear box (9), and the end water sealing rubber gasket (12) adopts an integral structure and has a redundant amount bulging outwards at the upper and lower split positions. The side water sealing rubber gaskets (13) and the side water sealing pressure plates (14) are both arranged on the front and back sides of the specimen (1) to seal the gap between the upper shear box (2) and the lower shear box (9). The left and right ends of the side water sealing rubber gaskets (13) and the side water sealing pressure plates (14) are both provided with an extension amount to ensure that when the lower shear box (9) moves left and right relative to the upper shear box (2) to the limit position, it can still be flexibly lapped with both ends of the end water sealing rubber gasket (12) to form a sealed storage cavity.

2. The test device for plugging rock fractures by inducing calcium carbonate deposition with soybean urease according to claim 1, characterized in that: The upper rock test block is cast from a transparent resin material, and the lower rock test block is made of real rock material.

3. The test device for plugging rock fractures by inducing calcium carbonate deposition with soybean urease according to claim 1, characterized in that: The upper shear box (2) fixes the upper rock test block by tightening the fastening bolt a (4). A rectangular observation port is provided at the top of the upper shear box (2) to cooperate with the transparent upper rock test block, enabling visual observation of the slurry flow and calcium carbonate deposition inside the fracture surface. The upper shear box (2) is slidably connected to the vertical support rod (5) through a horizontal connecting rod (3) with a sleeve at the end, and is fixed by tightening the fastening bolt b (6) arranged in the sleeve. Four vertical support rods (5) are provided corresponding to the upper shear box (2).

4. The test device for plugging rock fractures by inducing calcium carbonate deposition with soybean urease according to claim 1, wherein: A roller is installed in the horizontal rolling groove (8) to achieve the horizontal movement of the lower shear box (9), and the horizontal movement of the lower shear box (9) is realized by a hand-operated push rod (18).

5. The test device for plugging rock fractures by inducing calcium carbonate deposition with soybean urease according to claim 1, characterized in that: Scales are marked on the surface of the vertical support rod (5), and a horizontal scale (19) is provided at the edge of the horizontal rolling groove (8).

6. The test device for plugging rock fractures by soybean urease-induced calcium carbonate deposition according to claim 1, wherein: The side water-sealing pressure plate (14) is fixed and pressed through an "L"-shaped pressure plate support frame (16) and fastening bolts (15), and the pressure plate support frame (16) is fixed on the base (7) through fixing bolts (17).

7. The test device for plugging rock fractures by inducing calcium carbonate deposition with soybean urease according to claim 1, characterized in that: The end water-sealing rubber pad (12) is made of industrial rubber sheet, and the side water-sealing rubber pad (13) is made of silica gel material.

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