A fissure coal body grouting reinforcement experiment method and grouting reinforcement experiment mold

Abstract

The application discloses a kind of fissure coal body grouting reinforcement experimental method and grouting reinforcement experimental mould, experimental method includes the following steps: S1: from the coal block obtained from the scene and drill cylindrical coal sample;S2: along the bedding direction of coal sample and split, make coal sample along self bedding surface form fissure;S3: coal sample is placed in grouting reinforcement experimental mould inside;S4: grouting reinforcement experimental mould is fastened;S5: using syringe and grout are injected into fissure by syringe;S6: stop grout injection of syringe;S7: after grouting ends 24h, coal sample is taken out from mould, after maintenance, sequentially carry out uniaxial compression test, tensile fracture test and brazilian split test;S8: summarize the mechanism of grout reinforced fissure coal body;The application is collected from the coal mine of scene and has obvious bedding coal sample, to ensure test accuracy;And using grouting reinforcement experimental mould, coal sample is constrained to improve the reliability of test;Therefore, the application is convenient for the coal sample after grout is fully filled, penetrates and consolidates to carry out experiment, improves experimental effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mass grouting reinforcement, in particular to a fissure coal mass grouting reinforcement experiment method and a grouting reinforcement experiment mold. BACKGROUND

[0002] Based on the fissures developed in the coal body, the overall strength and stability of the coal body can be seriously weakened, so the existing technology often reinforces the fissure coal body through grouting technology, so that the grout fills, penetrates and consolidates in the fissure of the coal body under the action of grouting pressure, and the grout and the coal body form a unified whole, thereby effectively improving the stability of the coal body.

[0003] However, there are few studies on fissure coal mass grouting reinforcement in the prior art, and there is a lack of quantitative analysis of the reinforcement effect of fissure coal mass by indoor grouting test; and because the anisotropy of the coal body is significant, the mechanical properties and failure modes of coal samples with different bedding angles are significantly different; at the same time, when considering fissure coal body, the existing technology often directly cuts to form relatively smooth fissure surface or prepares regular structure fissure surface, which is quite different from the fissure coal body in the field, which adversely affects the experimental results. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a fissure coal mass grouting reinforcement experiment method and a grouting reinforcement experiment mold to solve the above problems in the prior art, the present application collects coal samples with obvious bedding from the coal mine in the field to ensure the accuracy of the test, and uses the grouting reinforcement experiment mold to constrain the coal sample to improve the reliability of the test, thereby facilitating the test on the fissure coal sample after grouting and improving the experimental effect.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is:

[0006] A fissure coal mass grouting reinforcement experiment method, comprising the following steps:

[0007] S1: fixing the coal blocks in the field, drilling cylindrical coal samples and samples from the coal blocks; wherein the size of the coal sample and the sample is consistent;

[0008] S2: fixing the coal sample and splitting along the bedding direction of the coal sample to form fissures along the bedding surface of the coal sample;

[0009] S3: wrapping a protective layer outside the coal sample and placing the coal sample inside a grouting reinforcement experiment mold symmetrical divided into two halves;

[0010] S4: fastening the grouting reinforcement experiment mold divided into two halves;

[0011] S5: using a syringe to pass through the protective layer and injecting grout into the fissure through the syringe;

[0012] S6: stopping the grout injection of the syringe after the slurry overflows;

[0013] S7: taking out the coal sample from the mold after 24 hours of grouting, and after curing, sequentially performing uniaxial compression test, tensile fracture test and Brazilian splitting test;

[0014] S8: comprehensively comparing and analyzing the mechanical properties and failure modes of the sample and the coal sample after grouting, the wetting properties of the slurry, the microstructure of the slurry-coal sample, the cementation of the slurry-coal interface and the crack propagation law, and summarizing the mechanism of the slurry reinforced fractured coal body.

[0015] Preferably, in step S1, the first coal sample and the second coal sample are obtained respectively;

[0016] The first coal sample is used for uniaxial compression test and tensile fracture test, and the height-diameter ratio is 2:1.

[0017] The second coal sample is used for Brazilian splitting test, and the height-diameter ratio is 1:2.

[0018] Preferably, the angle of the bedding direction of the coal sample is set to 0-90 degrees.

[0019] Preferably, the width of the crack of the coal sample is 1-7mm.

[0020] A grouting reinforcement experimental mold is applied to the above-mentioned grouting reinforcement experiment method for fractured coal body, comprising:

[0021] An inner membrane sleeve in a circular ring structure is divided symmetrically along the vertical plane; a liquid injection groove is formed in the side wall of the inner membrane sleeve along the vertical direction; an outer sleeve shell includes an upper cover and a base; the inner membrane sleeve is placed between the upper cover and the base; wherein the upper cover and the base are fixed by detachable connecting pieces.

[0022] Preferably, the cross-sectional shape of the upper cover and the base is consistent, and a plurality of fixing holes are arranged in a ring array around the center axis of the outer sleeve shell on the side; the detachable connecting pieces pass through the fixing holes.

[0023] Preferably, the detachable connecting pieces include a connecting screw and a threaded cap; wherein the connecting screw passes through the fixing hole, one end of which is inserted into the base, and the other end is externally sleeved with the threaded cap.

[0024] Preferably, it further comprises a tightening member sleeved on the outside of the inner membrane sleeve.

[0025] Preferably, the tightening member adopts a metal hoop, wherein the metal hoop is sleeved on the upper and lower ends of the inner membrane sleeve.

[0026] Preferably, water permeable stones are arranged on the opposite faces of the upper cover and the base.

[0027] The present application has the following beneficial effects:

[0028] First, the present application provides a kind of fissure coal body grouting reinforcement experimental method, by collecting the coal sample with obvious bedding from the coal mine on site, and using grouting reinforcement experimental mold, coal sample is constrained, to improve the reliability of test;At the same time, slurry is injected into fissure, axial and radial pressure is applied to coal sample, to ensure that slurry is fully filled, penetrated and consolidated;Therefore, it is convenient to carry out experiment on fissure coal sample after grouting, and improve experimental effect.

[0029] Second, the present application provides a kind of grouting reinforcement experimental mold, which is wrapped around the coal sample and injects slurry into the coal sample through the liquid injection groove;At the same time, the coal sample is constrained in axial and radial directions by tightening member and detachable connecting member;Therefore, it is convenient to carry out experiment on fissure coal sample after grouting, and improve experimental effect. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The overall structure diagram of the grouting reinforcement experimental mold provided by the present application is shown in the figure;

[0031] Figure 2 The top view of the grouting reinforcement experimental mold provided by the present application is shown in the figure;

[0032] Figure 3 The front view of the inner membrane sleeve in the grouting reinforcement experimental mold provided by the present application is shown in the figure.

[0033] Among them: 1, inner membrane sleeve;2, liquid injection groove;3, upper cover;4, threaded cap;5, fissure;6, base;7, water permeable stone;8, liquid injection pipe;9, protective layer;10, metal hoop;11, syringe. DETAILED DESCRIPTION

[0034] The present application will be further described in detail below in combination with the drawings and specific preferred embodiments.

[0035] In the description of the present application, it should be understood that the terms "left side", "right side", "upper part", "lower part" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and "first", "second" and the like do not represent the importance of the parts, so it cannot be understood as a limitation on the present application. The specific dimensions used in the present embodiment are only for the purpose of illustrating the technical scheme, and do not limit the protection scope of the present application.

[0036] The application provides a fissure 5 coal body grouting reinforcement experiment method, which comprises the following steps:

[0037] S1: selecting a coal block with high integrity and no obvious damage for testing; wherein, the coal block is fixed on site; a cylindrical coal sample with a diameter of about 38mm is drilled from the coal block using a water drill for uniaxial compression test / tension fracture test, and a cylindrical coal sample with a diameter of about 50mm is drilled from the coal block using a water drill for Brazilian splitting test; at the same time, cylindrical samples of the same size are drilled from the coal block; and the two ends of the sample are polished using a grinding machine, the height-diameter ratio of the coal sample for uniaxial compression test and tension fracture test is 2:1; the height-diameter ratio of the coal sample for Brazilian splitting test is 1:2; wherein, the placement angle of the coal block can be changed, and the coal sample with a bedding inclination angle (defined as the angle between the bedding plane and the horizontal plane) selected from the bedding direction angle of 0-90 degrees is 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees; wherein, the coal sample with obvious damage is treated as unqualified.

[0038] S2: fixing the coal sample using a tiger mouth flat clamp type clamping device, and splitting the coal sample along the bedding direction using a hexagonal flat chisel to form a fissure 5 along the bedding plane of the coal sample (the width of the fissure 5 of the coal sample is 1-7mm, and specifically 1mm, 3mm, 5mm and 7mm can be used), and preparing the coal sample with a fissure 5 with an inclination angle of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees; wherein, the coal sample deviating from the bedding direction or having abnormal fissure 5 surface during splitting is listed as unqualified; thereby, the pre-prepared fissure 5 surface is close to the fracture surface formed by natural damage, and the simulation effect of the test is improved.

[0039] S3: wrapping a soft and transparent protective layer 9 such as a preservative film around the outside of the coal sample, and placing the coal sample in a symmetrical half grouting reinforcement experiment mold.

[0040] S4: fastening the half grouting reinforcement experiment mold using a detachable connecting piece matched with a connecting screw and a threaded cap 4; wherein, when tightening the threaded cap using a torque wrench, a screwdriver and other tools, it should be ensured that the circumferential constraint and the axial constraint are consistent in each grouting test; thus, the number of rotations of the fixed torque wrench, screwdriver and other tools can be used to achieve this.

[0041] S5: using a syringe 11 to pass through the protective layer 9, and injecting the slurry into the fissure 5 through the syringe 11.

[0042] S6: stopping the slurry injection of the syringe 11 after the slurry overflows.

[0043] S7: after 24 hours of grouting, the coal sample is taken out of the mold, and after curing, uniaxial compression test, tension fracture test and Brazilian splitting test are sequentially performed.

[0044] S8: The mechanical properties of the sample and the coal sample after grouting, the failure mode, the wettability of the slurry, the microstructure of the slurry-coal interface, the cementation of the slurry-coal interface and the crack propagation law are comprehensively analyzed and compared, and the mechanism of the slurry reinforced crack 5 coal body is summarized.

[0045] Among them, the specific macroscopic mechanical test needs to set different variables, specifically considering the different cases of crack 5 position in the upper, middle and lower parts of the coal sample; and the different cases of crack 5 inclination angle of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees; and the different cases of crack 5 width of 1, 3, 5 and 7 mm; thereby, the effect of slurry grouting reinforcement is verified according to the design test of multiple factors.

[0046] Among them, the macroscopic mechanical test needs to meet the following conditions:

[0047] (1) Uniaxial compression test, tensile fracture test and full-process video recording of sample failure process are carried out on coal samples with different bedding angles; Brazil splitting test is carried out on coal samples with different angles between loading direction and bedding surface; among them, uniaxial compression test uses displacement control for loading, and the loading rate is 0.01 mm / s, and the loading rate of Brazil splitting test is 0.5 KN / s;

[0048] (2) Uniaxial compression test and tensile fracture test are carried out on coal samples with different crack 5 angles, crack 5 positions and crack 5 widths, and the stress-strain curves, peak strength, elastic modulus, peak strength deformation, crack propagation law and failure mode of the coal and the coal after grouting are compared and analyzed, especially the relationship between the crack propagation law of the grouting body in the loading process and the pre-crack 5 (grouting space), and the inhibitory effect of the grouting body on the crack 5 propagation is verified;

[0049] (3) Considering the time effect, uniaxial compression test is carried out on a certain type of crack 5 coal sample after grouting at different time periods, and the mechanical properties of the grouting reinforcement body are compared and analyzed as the time increases;

[0050] (4) Brazil splitting test is carried out on grouting samples with different angles between loading direction and crack 5 surface, and the peak strength, peak strength deformation and crack propagation law of the original coal and the grouting sample are compared and analyzed.

[0051] The following are a few test examples:

[0052] First, uniaxial compression test (not less than 3 groups of coal samples and samples for each group of experiments) (based on different cases of crack 5 inclination angle of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees; and different cases of crack 5 width of 1, 3, 5 and 7 mm;

[0053] First, use displacement control to test loading, set the displacement rate of 0.01 mm / s, and record the whole process of coal sample failure process; Then, comparative analysis of different types of coal samples and its stress-strain curve after grouting, peak strength, elastic modulus, peak strength deformation, crack propagation mode, failure mode, especially the relationship between the grouting body and the pre-crack 5 (slurry filling space) in the loading process, to verify the inhibitory effect of slurry on crack 5 expansion; Among them, the pre-crack space has been filled with slurry; At this time, the crack propagation refers to the crack propagation mode of the whole coal sample in the loading process.

[0054] Second, tensile fracture test (not less than 3 groups of coal samples and samples for each group of experiments) (based on different situations of crack 5 inclination angle of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees; And, crack 5 width of 1, 3, 5 and 7 mm;

[0055] First, use the bonding strength tester to test; Then, evenly smear AB glue on both ends of the coal sample, connect the upper end with the pull joint of the tester, and bond the bottom end to the water platform; Calculate the tensile fracture strength of the sample by measuring the maximum tensile force; Compare the tensile failure cross-section morphology of the sample and the coal sample after grouting and the relationship between the cross-section and the pre-crack surface (slurry filling space); If the cross-section is not at the original pre-crack 5, it means that the slurry-coal bonding strength is greater than the internal cohesion of the coal body, that is, the internal cohesion of the coal body.

[0056] Third, Brazilian splitting test (not less than 3 groups of coal samples and samples for each group of experiments) (based on different situations of crack 5 inclination angle of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees; And, crack 5 width of 1, 3, 5 and 7 mm;

[0057] First, set the loading rate to 0.5 KN / s, and compare the indirect tensile strength and crack propagation mode of the raw coal block and the coal sample after grouting with the crack 5 surface included angle of 0 degrees, 30 degrees, 45 degrees, 60 degrees and 90 degrees.

[0058] Meanwhile, the present application can also carry out the performance of slurry-coal interface; first, the surface tension of the slurry and the contact angle of the slurry on the coal body of different roughness are determined by the instrument, the wettability and affinity of the slurry to the coal are analyzed, then the microstructure morphology of the grouting coal body is scanned by the electron microscope scanning device (the magnification is 200X, 1000X, 3000X, 5000X, 8000X and 10000X), the microstructure of the slurry, the coal body and the slurry-coal contact surface is observed, the filling and penetration state of the slurry is analyzed, and the cementation characteristics of the slurry and coal are comprehensively studied; in this way, the present application compares and analyzes the mechanical properties and failure modes of the raw coal lump and the grouting crack 5 coal sample, the wettability of the slurry, the microstructure of the slurry and coal, the cementation of the slurry-coal interface and the crack propagation law, and the mechanism of the slurry reinforced crack coal body is summarized.

[0059] The present application also provides a grouting reinforcement experiment mold which is applied to the crack 5 coal body grouting reinforcement experiment method; comprising: an inner membrane sleeve 1 which is circular ring structure and is divided into two halves along the vertical plane; the side wall of the inner membrane sleeve 1 is provided with a liquid injection groove 2 along the vertical direction; an outer shell which comprises an upper cover 3 and a base 6; the inner membrane sleeve 1 is placed between the upper cover 3 and the base 6; wherein the upper cover 3 and the base 6 are fixed by detachable connecting pieces.

[0060] Referring to Figure 1 and 2 , the coal sample is wrapped with a protective layer 9 such as a plastic wrap, and then the inner membrane sleeve 1 which is divided into two halves is wrapped around the coal sample from both sides; then, the wrapped inner membrane sleeve 1 is placed on the base 6 and covered with the upper cover 3; at this time, the upper cover 3 and the base 6 are connected and fixed by the detachable connecting pieces, and the axial and radial reinforcement and fixation of the coal sample are completed.

[0061] The cross-sectional shape of the upper cover 3 and the base 6 is consistent, and a plurality of fixing holes are arranged in a ring array around the center axis of the outer shell on the side; the detachable connecting pieces pass through the fixing holes, thereby completing the axial fixation of the coal sample and improving the reaction effect of the coal sample and the slurry.

[0062] The detachable connecting pieces comprise a connecting screw and a threaded cap 4; wherein the connecting screw passes through the fixing hole, one end of which is inserted into the base 6, and the other end is externally sleeved with the threaded cap 4.

[0063] Referring to Figure 1 and Figure 3 , the connecting screw passes through the fixing hole and the threaded cap 4 is tightened, the reinforcement of the detachable connecting pieces is completed, and the coal sample is fully fixed inside the mold.

[0064] Referring to Figures 1-3 , the present application also uses a tightening piece which is sleeved outside the inner membrane sleeve 1; wherein the tightening piece adopts a metal hoop 10, and the metal hoop 10 is sleeved on the upper and lower ends of the inner membrane sleeve 1.

[0065] To ensure sufficient water permeation of the coal sample, water permeable stones 7 are provided on the opposite faces of the upper cover 3 and the base 6.

[0066] The embodiments of the present application described above are merely intended to illustrate the present application, but the present application is not limited to the described embodiments. Various changes, modifications, replacements and variations of the embodiments can be made by those skilled in the art without departing from the principles and spirit of the present application, and still fall within the protection scope of the present application.

Claims

1. A fractured coal body grouting reinforcement experimental method, characterized in that: The following steps are involved: S1: Fix the coal block on site and drill cylindrical coal samples and test specimens from the coal block; the coal sample and test specimen are of the same size; S2: Fixing the coal sample and splitting along the bedding direction of the coal sample to form cracks along the bedding plane of the coal sample (5); S3: Wrapping a protective layer (9) on the outside of the coal sample, and placing the coal sample inside a grouting reinforcement experimental mold that is symmetrically divided into two halves; S4: tightening the grouting reinforcement experimental mold divided into two halves; S5: using a syringe (11) to penetrate the protective layer (9) and injecting the slurry into the fissure (5) through the syringe (11); S6: After the slurry overflows, stop injecting the slurry into the syringe (11); S7: 24 hours after the grouting is completed, the coal sample is taken out from the mold, and after curing, uniaxial compression test, tensile fracture test and Brazilian splitting test are carried out in sequence; S8: Conduct a comprehensive comparative analysis of the mechanical properties and failure modes of the specimen and the coal sample after grouting, the wetting properties of the slurry, the microstructure of the slurry-coal sample, the slurry-coal interface bonding conditions and the crack propagation law, and summarize the mechanism of slurry reinforcement of fractured coal body and the mechanism of slurry reinforcement of fractured (5) coal body.

2. The fractured coal body grouting reinforcement experimental method according to claim 1, characterized in that: In the step S1, a first coal sample and a second coal sample are obtained respectively; The first coal sample is used for uniaxial compression test and tensile fracture test, and its height-to-diameter ratio is 2:1; The second coal sample was used for the Brazilian splitting test, and its height-to-diameter ratio was 1:

2.

3. The fractured coal body grouting reinforcement experimental method according to claim 1, characterized in that: The angle of the bedding direction of the coal sample is set to 0-90 degrees.

4. The fractured coal body grouting reinforcement experimental method according to claim 1, characterized in that: The width of the cracks (5) of the coal sample is 1-7 mm.

5. A grouting reinforcement experimental mold, which is used in the grouting reinforcement experimental method for fractured coal bodies according to any one of claims 1 to 4; characterized in that: include: The inner membrane sleeve (1) is an annular structure and is divided symmetrically along a vertical plane. A liquid injection groove (2) is provided on the side wall of the inner membrane sleeve (1) along the vertical direction. The outer shell comprises an upper cover (3) and a base (6); the inner membrane sleeve (1) is placed between the upper cover (3) and the base (6); wherein the upper cover (3) and the base (6) are fixed by a detachable connecting piece.

6. The grouting reinforcement experimental mold according to claim 5, characterized in that: The cross-sectional shapes of the upper cover (3) and the base (6) are consistent, and a plurality of fixing holes are provided in a circular array on the side around the central axis of the outer shell; The detachable connecting piece passes through the fixing hole.

7. The grouting reinforcement experimental mold according to claim 6, characterized in that: The detachable connecting member comprises a connecting screw and a threaded cover (4); The connecting screw passes through the fixing hole, one end of the connecting screw is inserted into the base (6), and the other end is sleeved with the threaded cover (4).

8. The grouting reinforcement experimental mold according to claim 5, characterized in that: Also includes: The tightening piece is sleeved on the outside of the inner membrane sleeve (1).

9. The grouting reinforcement experimental mold according to claim 8, characterized in that: The tightening member is a metal hoop (10), wherein the metal hoop (10) is sleeved on the upper and lower ends of the inner membrane sleeve (1).

10. The grouting reinforcement experimental mold according to claim 5, characterized in that: Permeable stones (7) are provided on the opposing surfaces of the upper cover (3) and the base (6).

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