Coal gangue bulk in-situ grouting confined compression test device

Abstract

The utility model relates to rock mass performance test test device field, especially in kind of coal gangue dispersion in situ grouting side limit compression test device, including combination steel drum, tight hoop and base, the combination steel drum is combined by two semicircle steel drum pieces, the inner diameter is consistent on height, the outer diameter is gradually increased from top to bottom on height, tight hoop whole is a ring structure, the inner diameter is gradually increased from top to bottom on height, the inner diameter of tight hoop and the outer diameter of combination steel drum middle part match, the base is the round cake shape structure of two layers and integral forming, wherein the outer diameter of upper layer round cake and the inner diameter of combination steel drum are consistent, the outer diameter of lower layer round cake is greater than the outer diameter of combination steel drum, and the upper layer round cake and the corresponding lower layer round cake part are provided with drainage hole from top to bottom. The test device of the utility model makes the combination steel drum convenient to disassemble through the cooperation of tight hoop, guard mouth groove and two semicircle steel drum pieces, and it is beneficial to the observation of the damage condition of compression object.

Description

Technical Field

[0001] This utility model relates to the field of rock mass performance testing devices, and in particular to a lateral compression testing device for in-situ grouting of coal gangue granules. Background Technology

[0002] After coal seam mining, the roof strata collapse, forming a caving zone. The coal gangue within this zone is irregularly arranged, with numerous voids between them. Under the pressure of the overlying strata, these voids are gradually compressed and reduced, but this process can take years or even decades. This means that the surface will be affected by ground subsidence after coal seam mining. In-situ grouting of the goaf is an important method for controlling long-term surface subsidence. Grouting is performed by drilling grouting holes from the surface into the goaf, and then grouting is used to fill the voids between the coal gangue (this can be done in parts or all of the goaf) to control surface subsidence. However, determining the composition and proportion of the grouting material to ensure that the grout and the coal gangue-supported structure formed after grouting have sufficient support performance to better control surface subsidence remains a research challenge in this field.

[0003] Indoor confined compression tests are an important method for obtaining rock mass properties. Under confined compression test conditions, coal gangue granules are placed within a rigid sleeve, and lateral deformation is completely restricted, allowing only vertical uniaxial compression to simulate the uniaxial compression state of coal gangue granules in the caving zone of the strata. Axial loading is applied until the deformation stabilizes, and the relationship between stress, strain, and time in the coal gangue granules is obtained. In engineering applications, the compression modulus and compression coefficient obtained from confined compression tests can be used to predict surface subsidence.

[0004] However, existing lateral compression testing devices are mainly used for compression tests on single coal gangue or other loose materials, or for compression tests on single non-cemented coal gangue powder and / or fly ash slurry; they cannot perform lateral compression tests on mixed cemented bodies formed after in-situ grouting of coal gangue loose materials; and they are not convenient for observing the damage of the compressed object. Utility Model Content

[0005] To address the aforementioned technical problems, this utility model proposes an in-situ grouting lateral compression test device for coal gangue bulk materials, comprising a combined steel drum, a clamping hoop, and a base. The combined steel drum is composed of two semi-circular steel drum plates, with the inner diameter being consistent in height and the outer diameter gradually increasing in height from top to bottom. The clamping hoop is an overall circular ring structure, with the inner diameter gradually increasing in height from top to bottom. The inner diameter of the clamping hoop matches the outer diameter of the middle part of the combined steel drum. The base is a two-layer, integrally formed disc-shaped structure, wherein the outer diameter of the upper disc is consistent with the inner diameter of the combined steel drum, and the outer diameter of the lower disc is larger than the outer diameter of the combined steel drum. Drainage holes are provided from top to bottom on the upper disc and its corresponding lower disc portion.

[0006] Preferably, the two semi-circular steel barrels form a stepped connection structure in the radial direction.

[0007] Preferably, the slopes of the outer wall of the combined steel drum and the inner wall of the clamping hoop meet the following conditions:

[0008] μFcosθ>Fsinθ

[0009] In the formula: F—the resultant force on the hoop; μ—the coefficient of friction of the outer wall of the composite steel barrel; θ—the slope between the outer wall of the composite steel barrel and the inner wall of the hoop.

[0010] Preferably, a rectangular insert is provided at the lower middle position of the outer wall of each semi-circular steel barrel piece, and two rectangular pieces are provided on the corresponding base, forming a slot between the two rectangular pieces for the rectangular insert to be inserted.

[0011] Preferably, it also includes a protective groove; the protective groove is a circular ring structure, and its inner diameter is divided into upper and lower parts according to its size. The inner diameter of the upper protective groove is consistent with the inner diameter of the combined steel drum, and the inner diameter of the lower protective groove gradually increases from top to bottom in height; the inner diameter of the lower protective groove matches the outer diameter of the top of the combined steel drum.

[0012] Preferably, it also includes a stamping plate; the stamping plate has a disc-shaped structure and its inner diameter is the same as that of the combined steel barrel.

[0013] Preferably, it also includes a steel gasket; the steel gasket has a disc-shaped structure and its inner diameter is the same as the inner diameter of the combined steel barrel.

[0014] Preferably, a blind hole groove is provided on the outer wall of the combined steel barrel for placing the acoustic emission probe.

[0015] The beneficial effects of this utility model are as follows: 1. The test device of this utility model makes it easy to disassemble the combined steel barrel by means of the tight hoop, the protective groove and the two semi-circular steel barrel pieces, which is conducive to observing the damage of the compressed object.

[0016] 2. In this utility model, the combined steel barrel and the base are connected by a plug-in structure, which is convenient for disassembly and assembly. The base is provided with drainage holes and steel gaskets, which can be used to conduct compression tests on simple solid objects or in-situ grouting lateral compression tests on coal gangue.

[0017] 3. The inner diameter of the protective groove of this utility model can be divided into upper and lower parts according to its size. The lower part of the protective groove serves the same function as the hoop to fix the combined steel barrel. The upper part of the protective groove can be regarded as an extension of the combined steel barrel in height. When adding material, the protective groove can be removed to facilitate the control of the amount of material added. The protective groove on the front cover of the compression is convenient for placing the stamping plate. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the assembly structure of the in-situ grouting side-confined compression test device for coal gangue granules according to this utility model;

[0020] Figure 2 This is an exploded structural diagram of the in-situ grouting side-confined compression test device for coal gangue granules according to this utility model;

[0021] Figure 3 This is a schematic diagram of the vertical cross-section of the protective groove of this utility model;

[0022] Figure 4 This is a top view of the combined steel cylinder of this utility model;

[0023] Figure 5 This is a top view of the base 6 of this utility model;

[0024] In the diagram: 1-Stamping plate; 2-Steel gasket; 3-Groove; 4-Combined steel barrel; 5-Clamping hoop; 6-Base; 7-Blind hole groove; 81-Insertion piece; 82-Slot; 9-Drain hole. Detailed Implementation

[0025] The technical solution of this utility model will now be clearly and completely described with reference to specific embodiments and accompanying drawings. In the illustrated embodiments, the directional representations, such as up, down, left, right, front, and back, are relative and are used to explain the relative structures of different components in this utility model. These representations are appropriate when the components are in the positions shown in the figures. However, if the description of the component positions changes, then these representations are also considered to change accordingly.

[0026] Example 1

[0027] like Figure 1-5As shown, this utility model proposes an in-situ grouting lateral compression test device for coal gangue bulk, including a protective groove 3, a combined steel barrel 4, a clamping hoop 5, and a base 6. The combined steel barrel 4 is composed of two semi-circular steel barrel pieces, with the connecting surfaces of the two semi-circular steel barrel pieces arranged vertically, that is, the combined steel barrel 4 is divided into two halves in the vertical direction. The two semi-circular steel barrel pieces form a stepped connecting structure in the radial direction to increase the contact area at the connection point and thus improve the tightness of the connection. The stepped connecting structures of the two semi-circular steel barrel pieces are staggered and interlocked, with each stepped connecting structure occupying about 6° of the entire circumferential angle of the combined steel barrel 4. The purpose of dividing the combined steel barrel 4 into two halves in the vertical direction is to disassemble the test device to observe the characteristics of the compressed object without damaging it. The inner diameter of the combined steel barrel 4 is set between 100 and 300 mm, and the height is 1 to 2 times the inner diameter. The ratio of the inner diameter of the combined steel barrel 4 to the maximum particle size of the coal gangue should not be less than 5.

[0028] The inner diameter of the combined steel drum 4 is uniform in height, while the outer diameter gradually increases in height from top to bottom, forming an angle θ of 1–3°. The clamping hoop 5 is an overall circular ring structure, with its inner diameter gradually increasing in height from top to bottom, forming an angle θ of 1–3°. The inner diameter of the clamping hoop 5 matches the outer diameter of the middle part of the combined steel drum 4, allowing the clamping hoop 5 to fit into the combined steel drum 4 at this position, so that the two semi-circular steel drum pieces are tightly connected at the stepped connection structure. Specifically, the angle θ meets the following requirements:

[0029] μFcosθ>Fsinθ

[0030] Right now:

[0031] μ>tanθ

[0032] Where: F—the resultant force on the hoop; μ—the coefficient of friction of the outer wall of the composite steel barrel; θ—the slope between the outer wall of the composite steel barrel and the inner wall of the hoop;

[0033] The thickness of the clamp 5 is greater than 30mm and the height is about 40mm. Considering that the compressive strength of the object being compressed is 5 to 10MPa and the axial pressure is about 15MPa, plus the strength of the safety redundancy, the strength of the combined steel barrel 4 must at least meet the requirement of not deforming under 20MPa.

[0034] The base 6 is a two-layer, integrally formed disc-shaped structure with the upper and lower discs concentrically positioned. The outer diameter of the upper disc is the same as the inner diameter of the combined steel barrel 4, while the outer diameter of the lower disc is larger than that of the combined steel barrel 4, allowing the combined steel barrel 4 to be inserted into the base 6. The thickness of the lower disc is greater than that of the upper disc. Drainage holes 9 are provided from top to bottom on the upper disc and its corresponding lower disc portion. To improve the stability of the connection between the combined steel barrel 4 and the base 6, a rectangular insert 81 is provided at the lower middle position of the outer wall of each semi-circular steel barrel piece. Two rectangular pieces are provided on the corresponding base 6, forming a slot 82 between the two rectangular pieces for the rectangular insert 81 to be inserted.

[0035] The protective groove 3 is a circular structure. Its inner diameter can be divided into upper and lower parts according to its size. The inner diameter of the upper protective groove is the same as the inner diameter of the combined steel drum 4. The inner diameter of the lower protective groove gradually increases from top to bottom, forming an angle of 1 to 3°. The inner diameter of the lower protective groove matches the outer diameter of the top of the combined steel drum 4, so that the lower protective groove can cooperate with the combined steel drum 4 at this position, making the two semi-circular steel drum pieces tightly connected at the stepped connection structure. That is, the lower protective groove plays the same role as the clamp 5 in fixing the combined steel drum 4. The upper protective groove can be regarded as an extension of the combined steel drum 4 in height. When adding material, removing the protective groove 3 makes it easier to control the volume of material added. The protective groove on the front cover is consistent with the inner diameter of the combined steel drum 4, so the stamping plate 1 can move smoothly downward. The height of the protective groove is 50mm to 80mm.

[0036] It also includes a stamping plate 1 and a steel gasket 2. Both the stamping plate 1 and the steel gasket 2 are disc-shaped structures. The function of the steel gasket 2 is to be placed inside the combined steel drum 4 before feeding to seal the drainage hole 9 for the compression test of coal gangue bulk (excluding water or slurry). The function of the stamping plate 1 is to be placed into the protective groove 3 after feeding. The pressure head of the uniaxial compression test machine compresses the compressed object inside the combined steel drum 4 through the stamping plate 1, so that the compressed object is subjected to uniform force.

[0037] A blind hole groove 7 is provided on the outer wall of the combined steel barrel 4 for placing the acoustic emission probe; in addition, sealing devices are provided at the stepped connection structure of the combined steel barrel 4, the connection between the combined steel barrel 4 and the base, and the connection of the opening groove of the combined steel barrel 4. Since setting a seal between the connected objects is a conventional method in this field, it will not be described in detail here.

[0038] Example 2

[0039] The lateral compression testing apparatus based on one embodiment can perform at least the following two types of lateral compression tests:

[0040] Experiment 1: Lateral confinement compression test of simple coal gangue bulk can be used to simulate the compression process of crushed coal gangue in goaf under the pressure of overlying strata;

[0041] Step 1: Assemble the lateral confinement compression test apparatus;

[0042] Step 2: Determine the gradation of the coal gangue bulk and mix it evenly;

[0043] Step 3: Place the steel gasket 2 inside the combined steel drum 4; pour in the coal gangue evenly until the combined steel drum 4 is full;

[0044] Step 4: Install the protective groove 3 and the acoustic emission probe, and place the lateral compression test device on the uniaxial compression test machine;

[0045] Step 5: Place the stamping plate 2 in the self-protecting groove, and align the pressure head of the uniaxial compression test device with the center of the stamping plate 2. Perform uniaxial compression according to the test requirements. After a certain period of time, end the uniaxial compression test and collect the data during the test.

[0046] Experiment 2: Lateral confined compression test of mixed cementitious body can be used to simulate the compression process of mixed cementitious body formed after grouting and filling of crushed coal gangue in goaf under the pressure of overlying strata;

[0047] Step 1: Assemble the lateral confinement compression test apparatus;

[0048] Step 2: Determine the gradation of the coal gangue granules and mix them evenly; determine the material and concentration of the filling slurry, and prepare an appropriate amount of slurry, which can be cement slurry or a mixture of cement and fly ash;

[0049] Step 3: Place a filter element (filter screen) and PP cotton with a thickness that is basically the same as that of the steel gasket 2 inside the combined steel barrel 4. The inner diameter of the PP surface is the same as the inner diameter of the steel gasket 2 and the combined steel barrel 4. Apply machine grease to the drain hole 9 of the base 6 to seal the drain hole 9.

[0050] Step 4: Pour coal gangue evenly into the combined steel drum 4 until it is full; then pour in the filling slurry; remove the mechanical grease so that the drainage hole 9 can drain the water in the slurry, simulating the process of the filling slurry seeping water into the surrounding coal and rock mass during the actual filling process; cover the protective groove and let it stand for 1 day.

[0051] Step 5: After the mixed cementitious body has initially solidified, disassemble the lateral compression test device, take out the mixed cementitious body and remove the bottom filter element (filter screen) and PP cotton; place the mixed cementitious body in a cool place for 28 days;

[0052] Step 6: Reinstall the lateral compression test device. Place the steel gasket 2 and the mixed cementitious body into the combined steel barrel 4 in sequence; install the protective groove 3 and the acoustic emission probe; place the lateral compression test device on the uniaxial compression test machine.

[0053] Step 7: Place the stamping plate 2 in the self-protecting groove, and align the pressure head of the uniaxial compression test device with the center of the stamping plate 2. Perform uniaxial compression according to the test requirements. After a certain period of time, end the uniaxial compression test and collect the data during the test.

[0054] The detailed descriptions listed above are merely specific descriptions of feasible implementations of this utility model, and are not intended to limit the scope of protection of this utility model. All equivalent implementations or modifications made without departing from the spirit of this utility model should be included within the scope of protection of this utility model.

Claims

1. A test device for in-situ grouting and lateral compression of coal gangue granules, characterized in that, The system includes a combined steel drum, a clamping hoop, and a base. The combined steel drum is composed of two semi-circular steel drum plates with the same inner diameter at the same height, and the outer diameter gradually increases from top to bottom. The clamping hoop is a circular ring structure with the inner diameter gradually increasing from top to bottom. The inner diameter of the clamping hoop matches the outer diameter of the middle part of the combined steel drum. The base is a two-layer, integrally formed disc-shaped structure, where the outer diameter of the upper disc is the same as the inner diameter of the combined steel drum, and the outer diameter of the lower disc is larger than the outer diameter of the combined steel drum. Drainage holes are provided on the upper disc and its corresponding lower disc portion from top to bottom.

2. The lateral compression testing apparatus according to claim 1, characterized in that, The two semi-circular steel barrels form a stepped connection structure in the radial direction.

3. The lateral compression testing apparatus according to claim 1, characterized in that, The slopes of the outer wall and the inner wall of the clamping hoop of the combined steel drum must meet the following conditions: μFcosθ>Fsinθ In the formula: F—the resultant force on the hoop; μ—the coefficient of friction of the outer wall of the combined steel barrel; θ—the slope between the outer wall of the combined steel barrel and the inner wall of the hoop.

4. The lateral compression testing apparatus according to claim 1 or 2, characterized in that, Each semi-circular steel barrel has a rectangular insert at the lower center of its outer wall, and two rectangular plates are placed on the corresponding base, forming a slot between the two rectangular plates for the rectangular insert to be inserted.

5. The lateral compression testing apparatus according to any one of claims 1-3, characterized in that, It also includes a protective groove; the protective groove is a circular structure, and its inner diameter is divided into upper and lower parts according to its size. The inner diameter of the upper protective groove is the same as the inner diameter of the combined steel drum, and the inner diameter of the lower protective groove gradually increases from top to bottom in height; the inner diameter of the lower protective groove matches the outer diameter of the top of the combined steel drum.

6. The lateral compression testing apparatus according to any one of claims 1-3, characterized in that, It also includes a stamping plate; the stamping plate has a disc-shaped structure and its inner diameter is the same as that of the combined steel drum.

7. The lateral compression testing apparatus according to any one of claims 1-3, characterized in that, It also includes steel gaskets; the steel gaskets are disc-shaped structures with an inner diameter consistent with the inner diameter of the combined steel drum.

8. The lateral compression testing apparatus according to any one of claims 1-3, characterized in that, Blind slots are provided on the outer wall of the combined steel drum to accommodate acoustic emission probes.

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