A device and method for testing in-situ swelling force of high-swelling mudstone

Abstract

The present application relates to a kind of high swelling mudstone in situ swelling force testing device and testing method, belong to mudstone swelling force testing equipment technical field.Testing device includes upper water injection pipe, lower water injection pipe, upper water permeation mechanism, lower water permeation mechanism, annular pressure sensor and water tank, wherein, upper water permeation mechanism, annular pressure sensor and lower water permeation mechanism are connected through introduction steel pipe, and the bottom of introduction steel pipe is set in lower water permeation mechanism, and the top of introduction steel pipe is worn out upper water permeation mechanism, and lower water injection pipe is arranged in introduction steel pipe, upper water injection pipe is arranged in the side of upper water permeation mechanism, and upper water injection pipe and lower water injection pipe top are connected with water tank.The present application can obtain the expansion force size of swelling mudstone directly under in situ test condition, quickly obtain the in situ swelling characteristics of swelling rock mass, avoid the error and overlong test period caused by disturbance under laboratory condition, and the test result is more in line with real condition.

Description

Technical Field

[0001] This invention relates to an in-situ expansion force testing device and method for highly expansive mudstone, belonging to the technical field of mudstone expansion force testing equipment. Background Technology

[0002] Expansive mudstone is a geological body with significant swelling and shrinkage properties formed during natural geological processes. Its clay content is mainly composed of the strongly hydrophilic minerals montmorillonite and illite. It exhibits undesirable properties such as swelling upon contact with water, shrinking upon loss of water, overconsolidation, and high fissure density. In mine roadway construction, highly expansive mudstone floors with these properties pose a significant threat to roadway stability, easily inducing large deformations and floor heave disasters, hindering rapid tunneling operations, and seriously affecting safe mine production. Expansion force is a direct indicator reflecting the swelling characteristics of expansive mudstone and is one of the important parameters in the construction of roadways with expansive mudstone floors; therefore, expansion force testing is essential.

[0003] Currently, the technology for testing the swelling force of expansive mudstone under indoor experimental conditions is relatively mature. For example, in 2022, Guo Yongchun et al. pointed out in their article "Experimental Study on Triaxial Swelling Force of Red Bed Mudstone" that, in order to address the problem of the low swelling force test results of red bed mudstone in existing standards, they independently developed a triaxial swelling force testing device for expansive rocks. By adopting the method of placing the sample first and then adding constraints, they overcame the limitation of the release deformation gap between the rock and the container wall, and solved the problem of the low swelling force test results.

[0004] However, indoor test results are affected by factors such as sample size and test conditions, and cannot truly reflect the field conditions. Furthermore, indoor tests are affected by sample quality and have long testing cycles, while in-situ tests have short testing cycles, measure expansion force in the actual occurrence environment, and provide accurate and reliable results that better reflect the actual stress state. Therefore, in-situ expansion force testing of expansive rock masses is particularly important. This invention is proposed to address this issue. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an in-situ swelling force testing device for highly expansive mudstone. This device can directly obtain the swelling force of expansive mudstone under in-situ test conditions, quickly acquire the in-situ swelling characteristics of expansive rock masses, avoid errors caused by disturbances and excessively long test cycles under indoor conditions, and provide test results that better reflect real-world conditions.

[0006] The present invention also provides a testing method for the above-mentioned in-situ swelling force testing device for highly expansive mudstone.

[0007] The technical solution of the present invention is as follows:

[0008] A device for testing the in-situ swelling force of highly expansive mudstone includes an upper water injection pipe, a lower water injection pipe, an upper permeable mechanism, a lower permeable mechanism, an annular pressure sensor, and a water tank. The upper permeable mechanism, the annular pressure sensor, and the lower permeable mechanism are connected by a steel inlet pipe. The bottom of the steel inlet pipe is located inside the lower permeable mechanism, and the top of the steel inlet pipe extends out of the upper permeable mechanism. The lower water injection pipe is located inside the steel inlet pipe. An upper water injection pipe is located on one side of the upper permeable mechanism. The tops of the upper and lower water injection pipes are connected to the water tank.

[0009] According to a preferred embodiment of the present invention, the upper permeable mechanism uses an upper permeable stone, and the lower permeable mechanism uses a lower permeable stone. The upper and lower permeable stones have the same structure, both being cylindrical. Water is injected using the permeable stones to simulate the real underground mudstone swelling environment when exposed to water, thus ensuring the test results.

[0010] According to a preferred embodiment of the present invention, the upper permeable mechanism adopts an upper permeable block, and the lower permeable mechanism adopts a lower permeable block. The upper and lower permeable blocks have the same structure, which is a columnar block with several through-holes inside. Water is injected into the mudstone using the upper and lower permeable blocks, which is fast and allows for rapid testing experiments.

[0011] For quick testing, use permeable blocks and quickly fill them with water. To ensure test results and improve accuracy, use permeable stones.

[0012] According to a preferred embodiment of the present invention, the annular pressure sensor is connected to a display screen via a transmission line to display the reading, and the upper permeable mechanism has an outlet hole through which the transmission line passes.

[0013] According to a preferred embodiment of the present invention, a flow controller is provided at the connection between the upper water inlet pipe and the lower water inlet pipe and the water tank to monitor and control the water volume.

[0014] The testing method for the above-mentioned in-situ swelling force testing device for highly expansive mudstone is as follows:

[0015] (1) Drilling operations are carried out using a drilling rig at the measuring point location in the coal mine roadway. Two boreholes are prepared, one vertical and one inclined. Both boreholes penetrate the coal seam and extend into the expansive mudstone layer. The inclination angle of the inclined borehole is controlled within the range of 45° to 60°, and the borehole diameter is 8 to 10 cm. There is at least 1 meter of expansive mudstone around the two boreholes.

[0016] (2) Place the expansion force testing device into the two drill holes respectively;

[0017] (3) Water injection operation is carried out. As the water flows into the mudstone of the test section, the mudstone of the test section expands when it comes into contact with water, and gradually begins to squeeze the annular pressure sensor. The reading of the annular pressure sensor increases. As the water injection time increases, the reading of the annular pressure sensor gradually tends to a stable value. Record the change of the annular pressure sensor value over time throughout the process.

[0018] (4) The stable value in the vertical borehole is the in-situ horizontal expansion force. Combining the stable value in the inclined borehole and the stable value in the vertical borehole, the in-situ vertical expansion force is calculated according to the principle of force superposition. Thus, the in-situ vertical expansion force and the in-situ horizontal expansion force are obtained.

[0019] According to a further preferred embodiment of the present invention, in step (2), before the expansion force testing device is placed into the borehole, a lower sealing steel pipe is first placed into the borehole, and then the expansion force testing device and the upper sealing steel pipe are placed in sequence. The upper sealing steel pipe extends to the coal seam, and the upper and lower sealing steel pipes are used to support the boreholes on the upper and lower sides of the expansion force testing device, ensuring that the borehole deforms only in the radial direction and improving the accuracy of the expansion force test.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This invention can directly obtain the swelling force of expansive mudstone under in-situ test conditions, quickly obtain the in-situ swelling characteristics of expansive rock mass, avoid the errors caused by disturbance under indoor conditions and the excessively long test cycle, and the test results are more consistent with real conditions.

[0022] 2. This invention utilizes an upper water injection mechanism and a lower water injection mechanism to inject water from the upper and lower sides of the expansion testing device respectively, ensuring that the mudstone expands and is squeezed synchronously from top to bottom.

[0023] 3. This invention provides two permeable mechanisms. For rapid testing, permeable blocks are used to quickly inject water. For testing to ensure results and improve accuracy, permeable stones are used to meet different testing needs.

[0024] 4. This invention uses two boreholes for testing. The in-situ vertical expansion force and in-situ horizontal expansion force can be calculated using the obtained tilting force and horizontal force. The test is convenient, the calculation is simple, and the test results are more comprehensive.

[0025] 5. During testing, the upper and lower sealing steel pipes are used to support the drill holes on the upper and lower sides of the expansion force testing device, ensuring that the drill holes deform only in the radial direction, thereby improving the accuracy of the expansion force test. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is a schematic diagram of the structure of the present invention;

[0028] Figure 2 This is a schematic diagram of the mounting structure of the annular pressure sensor according to Embodiment 1 of the present invention;

[0029] Figure 3 This is a schematic diagram of the annular pressure sensor structure of the present invention;

[0030] Figure 4 This is a schematic diagram of the water tank structure of the present invention;

[0031] Figure 5 This is a schematic diagram of the drilling process of the present invention;

[0032] Figure 6 This is a schematic diagram of the permeable stone structure in Embodiment 2 of the present invention;

[0033] Figure 7 This is a schematic diagram of the permeable stone structure in Embodiment 2 of the present invention;

[0034] In the diagram: 1-Upper water injection pipe, 2-Lower water injection pipe, 3-Transmission line, 4-Outlet hole, 5-Upper permeable stone, 6-Inlet steel pipe, 7-Annular pressure sensor, 8-Nut, 9-Sealing rubber gasket, 10-Lower permeable stone, 11-Upper permeable block, 12-Upper water injection hole, 13-Steel pipe inlet hole, 14-Lower permeable block, 15-Display screen, 16-Water tank, 17-Flow controller, 18-Coal seam, 19-Expanding mudstone layer, 20-Drill hole, 21-Upper sealing steel pipe, 22-Lower sealing steel pipe. Detailed Implementation

[0035] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0036] Example 1:

[0037] like Figure 1-5 As shown, this embodiment provides an in-situ expansion force testing device for highly expansive mudstone, including an upper water injection pipe 1, a lower water injection pipe 2, an upper permeable mechanism, a lower permeable mechanism, an annular pressure sensor 7, and a water tank 16. The upper permeable mechanism, the annular pressure sensor 7, and the lower permeable mechanism are connected by an inlet steel pipe 6. The bottom of the inlet steel pipe 6 is located inside the lower permeable mechanism, and the top of the inlet steel pipe 6 extends out of the upper permeable mechanism. The lower water injection pipe 2 is located inside the inlet steel pipe 6. The upper water injection pipe 1 is located on one side of the upper permeable mechanism, and the top of the upper water injection pipe 1 and the lower water injection pipe 2 are connected to the water tank 16.

[0038] The upper permeable mechanism uses upper permeable stone 5, and the lower permeable mechanism uses lower permeable stone 10. The upper and lower permeable stones have the same structure, both being cylindrical. Water is injected using the permeable stones to simulate the real underground mudstone swelling environment when it comes into contact with water, ensuring the test results.

[0039] A nut 8 is fixedly installed on the permeable stone 10. The lower end of the inlet steel pipe 6 is fixed by the nut 8 connected by an internal thread, and a sealing rubber gasket 9 is used for sealing.

[0040] The annular pressure sensor 7 is connected to a display screen 15 via a transmission line 3 to display the reading. An outlet hole 4 for the transmission line is provided on the upper permeable stone 5. The annular pressure sensor 7 has a range of 0.5–900 kN, a sensitivity of 1.0–2.0 ± 0.1 mV / V, and an overall accuracy of 0.2% F·S.

[0041] A flow controller 17 is installed at the connection between the upper water inlet pipe 1 and the lower water inlet pipe 2 and the water tank 16 to monitor and control the water volume.

[0042] The testing method for the above-mentioned in-situ swelling force testing device for highly expansive mudstone is as follows:

[0043] (1) Drilling operations are carried out using a drilling rig at the measuring point location in the coal mine roadway. Two boreholes 20 are prepared, one is a vertical borehole and the other is an inclined borehole. Both boreholes penetrate the coal seam 18 and extend into the expansive mudstone layer 19. The inclination angle of the inclined borehole is controlled within the range of 45° to 60° and the borehole diameter is 8 to 10 cm. There is at least 1 meter of expansive mudstone around the two boreholes.

[0044] (2) Place the expansion force testing device into two boreholes respectively. Before placing the expansion force testing device into the borehole, first place the lower sealing steel pipe 22 into the borehole, and then place the expansion force testing device and the upper sealing steel pipe 21 in sequence. The upper sealing steel pipe 21 extends to the coal seam. The upper and lower sealing steel pipes are used to support the boreholes on the upper and lower sides of the expansion force testing device to ensure that the boreholes deform only in the radial direction and improve the accuracy of the expansion force test.

[0045] (3) Water injection operation is carried out. As the water flows into the mudstone of the test section, the mudstone of the test section expands when it comes into contact with water and gradually begins to squeeze the annular pressure sensor 7. The reading of the annular pressure sensor increases. As the water injection time increases, the reading of the annular pressure sensor gradually tends to a stable value. Record the change of the annular pressure sensor value over time throughout the process.

[0046] (4) The stable value in a vertical borehole is the in-situ horizontal expansion force σ. 水平 The stability value within the inclined borehole is the in-situ radial expansion force σ of the mudstone. 径向 Based on the principle of superposition of forces, the in-situ vertical expansion force σ is calculated. 竖直 :

[0047]

[0048] Thus, the in-situ vertical expansion force and the in-situ horizontal expansion force are obtained.

[0049] Example 2:

[0050] A device for testing the in-situ expansion force of highly expansive mudstone has the structure described in Example 1, except that the upper permeable mechanism uses an upper permeable block 11, which has a steel pipe inlet hole 13, an upper water injection hole 12, and an outlet hole. An inlet steel pipe is installed in the steel pipe inlet hole, and an upper water injection pipe is installed in the upper water injection hole. The lower permeable mechanism uses a lower permeable block 14. The upper and lower permeable blocks have the same structure, which is a columnar block with several through outlet holes inside. Water is injected into the mudstone using the upper and lower permeable blocks, which is fast and allows for rapid testing experiments.

[0051] The above description is not intended to limit the present invention, nor is the present invention limited to the examples given above. Any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A device for testing the in-situ swelling force of highly expansive mudstone, characterized in that, It includes an upper water inlet pipe, a lower water inlet pipe, an upper water permeation mechanism, a lower water permeation mechanism, an annular pressure sensor, and a water tank. The upper water permeation mechanism, the annular pressure sensor, and the lower water permeation mechanism are connected by a steel inlet pipe. The bottom of the steel inlet pipe is located inside the lower water permeation mechanism, and the top of the steel inlet pipe extends out of the upper water permeation mechanism. The lower water inlet pipe is located inside the steel inlet pipe. The upper water inlet pipe is located on one side of the upper water permeation mechanism. The tops of the upper water inlet pipe and the lower water inlet pipe are connected to the water tank.

2. The in-situ swelling force testing device for highly expansive mudstone as described in claim 1, characterized in that, The upper permeable mechanism uses upper permeable stone, and the lower permeable mechanism uses lower permeable stone. The upper and lower permeable stones have the same structure, both being cylindrical.

3. The in-situ swelling force testing device for highly expansive mudstone as described in claim 1, characterized in that, The upper permeable mechanism uses an upper permeable block, and the lower permeable mechanism uses a lower permeable block. The upper and lower permeable blocks have the same structure, which is a columnar block with several through-holes inside.

4. The in-situ swelling force testing device for highly expansive mudstone as described in claim 1, characterized in that, The ring pressure sensor is connected to a display screen via a transmission line, and the upper permeable mechanism has an outlet hole for the transmission line.

5. The in-situ swelling force testing device for highly expansive mudstone as described in claim 1, characterized in that, Flow controllers are installed at the connection points of the upper and lower water inlet pipes with the water tank.

6. The testing method of the in-situ swelling force testing device for highly expansive mudstone as described in any one of claims 1-5, characterized in that, The steps are as follows: (1) Drilling operations are carried out using a drilling rig at the measuring point location in the coal mine roadway. Two boreholes are prepared, one vertical and one inclined. Both boreholes penetrate the coal seam and extend into the expansive mudstone layer. The inclination angle of the inclined borehole is controlled within the range of 45° to 60°, and the borehole diameter is 8 to 10 cm. (2) Place the expansion force testing device into the two drill holes respectively; (3) Water injection operation is carried out. As the water flows into the mudstone of the test section, the mudstone of the test section expands when it comes into contact with water, and gradually begins to squeeze the annular pressure sensor. The reading of the annular pressure sensor increases. As the water injection time increases, the reading of the annular pressure sensor gradually tends to a stable value. Record the change of the annular pressure sensor value over time throughout the process. (4) The stable value in the vertical borehole is the in-situ horizontal expansion force. Combining the stable value in the inclined borehole and the stable value in the vertical borehole, the in-situ vertical expansion force is calculated according to the principle of force superposition. Thus, the in-situ vertical expansion force and the in-situ horizontal expansion force are obtained.

7. The testing method of the in-situ swelling force testing device for highly expansive mudstone as described in claim 6, characterized in that, In step (2), before the expansion force testing device is placed into the borehole, the lower sealing steel pipe is first placed into the borehole, and then the expansion force testing device and the upper sealing steel pipe are placed in sequence, with the upper sealing steel pipe extending to the coal seam.

Images