In-situ testing device and method for ring shear of collapsible soil

Abstract

The application discloses a collapsible soil body annular shearing in-situ testing device and method, wherein the device comprises a force applying module and an unfolding shearing module; the force applying module is arranged at the collapsible annular soil body in a testing hole and is used for applying a horizontal normal force to the collapsible annular soil body; and the unfolding shearing module is arranged in the testing hole, and an unfolding plate thereof is in contact with the lower surface of the collapsible annular soil body in an unfolding state and is used for applying a vertical upward shearing force to the collapsible annular soil body. According to the application, the collapsible annular soil body can be dug at a preset depth according to testing requirements, and the in-situ testing of the collapsible soil body can be realized by combining the force applying module and the unfolding shearing module, so that the soil body is not disturbed, the original structure of the soil body is reserved, the shearing strength of the collapsible soil body at different depths can be tested, the real situation of the deep soil body can be reflected, the accuracy is relatively high, and the requirements of engineering design and disaster control can be greatly met. Meanwhile, the testing device of the application is simple, low in cost and easy to operate.

Description

Technical Field

[0001] This invention discloses an in-situ testing device and method for the circumferential shear of collapsible soil, belonging to the technical field of shear performance testing of collapsible soil. Background Technology

[0002] Collapsible soil refers to unsaturated, structurally unstable soil that rapidly deteriorates and undergoes significant subsidence when inundated with water under pressure. Since some existing infrastructure is built on collapsible soil, it is crucial to pay close attention to its shear strength during preliminary investigations to improve infrastructure stability and prevent accidents.

[0003] Existing methods for obtaining shear strength parameters of collapsible soils include laboratory shear tests and in-situ shear tests. Laboratory shear tests, however, damage the structure of the collapsible soil during sampling, failing to reflect actual field conditions and exhibiting low accuracy. In contrast, in-situ shear tests offer advantages such as strong representativeness, minimal disturbance, and the ability to accurately reflect actual engineering conditions, thus greatly meeting the needs of engineering design and disaster mitigation.

[0004] Current in-situ shear testing devices require excavating test pits and leaving soil columns for shear testing, which is time-consuming and labor-intensive. Furthermore, they can only test surface soil and cannot test the shear strength of collapsible soil at different depths, making it difficult to reflect the true condition of deep soil. Summary of the Invention

[0005] The purpose of this application is to provide an in-situ testing device and method for circumferential shear strength of collapsible soil, so as to solve the technical problem that existing in-situ testing devices cannot perform shear strength testing on collapsible soil at different depths.

[0006] A first aspect of the present invention provides an in-situ testing device for annular shear of collapsible soil, comprising a force application module and an unfolding shear module;

[0007] The force application module is installed at the collapsible annular soil within the test hole and is used to apply a horizontal normal force to the collapsible annular soil.

[0008] The unfolding shear module is installed inside the test hole. Its unfolded plate is in contact with the lower surface of the collapsible annular soil in the unfolded state, and is used to apply a vertically upward shear force to the collapsible annular soil.

[0009] Preferably, the force application module includes a limiting cylinder and an airbag;

[0010] The limiting cylinder is fixedly installed inside the test hole and is at the same horizontal plane as the collapsible annular soil.

[0011] The airbag is fixedly disposed around the outer wall of the limiting cylinder;

[0012] The unfolding shearing module passes through the limiting cylinder along the axial direction of the limiting cylinder, and its unfolded end is in contact with the lower surface of the collapsible annular soil in the unfolded state.

[0013] Preferably, the deployable shearing module includes an extension rod, a shearing sub-module, and a cable;

[0014] One end of the extension rod passes through the force-applying module along the axial direction of the force-applying module;

[0015] The shearing sub-module is fixedly connected to one end of the extension rod that passes through the force application module;

[0016] The first end of the cable is slidably connected to the extension rod, and the second end is fixedly connected to the shearing sub-module, which is used to drive the unfolding plate of the shearing sub-module to rotate.

[0017] Preferably, the unfolding shearing module further includes a guide rail and a slider that matches the guide rail;

[0018] The guide rail is mounted on the body of the extension rod;

[0019] The slider is located at the first end of the cable.

[0020] Preferably, the shearing submodule further includes a fixing plate;

[0021] The fixing plate is fixedly connected to one end of the extension rod that passes through the force application module;

[0022] The edges of the unfolding plate and the fixed plate are rotatably connected;

[0023] The second end of the cable is fixedly connected to the unfolding plate.

[0024] Preferably, the number of the unfolding plates is multiple;

[0025] The plurality of the unfolding plates are arranged around the fixed plate.

[0026] Preferably, the shearing submodule further includes a support block;

[0027] The support block is located at the connection between the fixed plate and the unfolding plate, with its upper surface fixedly connected to the lower surface of the fixed plate and its upper surface also in contact with the lower surface of the unfolding plate.

[0028] Preferably, it also includes a data acquisition module and a display module;

[0029] The input end of the data acquisition module is connected to the force application module and the unfolding shearing module, respectively, and the output end is connected to the display module.

[0030] A second aspect of the present invention provides a method for in-situ testing of collapsible soil annular shear using the above-described collapsible soil annular shear in-situ testing device, comprising:

[0031] Prepare collapsible ring-shaped soil within the test well;

[0032] The force application module is placed inside the test hole and positioned at the same horizontal level as the collapsible annular soil mass to apply a horizontal normal force to the collapsible annular soil mass.

[0033] The unfolded shear module is inserted into the test hole, and its unfolded plate is in contact with the lower surface of the collapsible annular soil in the unfolded state, so as to apply a vertically upward shear force to the collapsible annular soil.

[0034] Preferably, the preparation of the collapsible annular soil mass within the test hole specifically includes:

[0035] The test hole is expanded within a preset range above and below a preset elevation to obtain a collapsible annular soil mass.

[0036] The in-situ testing device and method for circumferential shear of collapsible soil of the present invention has the following advantages compared with the prior art:

[0037] This invention allows for the excavation of collapsible annular soil at a preset depth, based on testing needs. It then combines a force application module and an unfolding shear module to achieve in-situ testing of the collapsible soil without disturbing its original structure. Furthermore, it enables shear strength testing of collapsible soil at different depths, thus reflecting the true condition of deep soil with high accuracy, greatly meeting the needs of engineering design and disaster management. Simultaneously, the testing device of this invention is simple, low-cost, and easy to operate. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the in-situ annular shear test device for collapsible soil in an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the unfolded plate of the unfolded shear module in the in-situ testing device for collapsible soil ring shear in an embodiment of the present invention, with the unfolded plate retracted.

[0040] Figure 3 This is a schematic diagram of the unfolding plate of the unfolding shear module in the in-situ testing device for collapsible soil ring shear in an embodiment of the present invention when unfolded;

[0041] Figure 4This is a schematic diagram of the contact between the collapsible annular soil and the shear submodule in the in-situ testing device for collapsible soil annular shear in an embodiment of the present invention.

[0042] Figure 5 This is a schematic diagram showing the shear strength parameters of collapsible annular soil obtained using the in-situ shear test method for collapsible soil in an embodiment of the present invention.

[0043] List of components and reference numerals:

[0044] 1 is the unfolding shearing module; 11 is the extension rod; 12 is the cable; 13 is the guide rail; 14 is the fixing plate; 15 is the unfolding plate; 16 is the support block; 2 is the test hole; 3 is the collapsible annular soil; 4 is the limiting cylinder; 5 is the airbag; 6 is the data acquisition module; 7 is the hole enlargement. Detailed Implementation

[0045] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0046] A first aspect of this invention provides an in-situ testing device for circumferential shear in collapsible soil, such as... Figure 1 As shown, it includes a force application module and an unfolding shear module 1;

[0047] The force application module is set at the collapsible annular soil 3 inside the test hole 2 to apply a horizontal normal force to the collapsible annular soil 3;

[0048] The unfolded shear module 1 is installed inside the test hole 2. Its unfolded plate 15 is in contact with the lower surface of the collapsible annular soil 3 in the unfolded state, and is used to apply a vertically upward shear force to the collapsible annular soil 3, thereby obtaining the shear strength of the collapsible soil that is simultaneously subjected to horizontal normal force and vertically upward shear force.

[0049] This invention allows for the excavation of a collapsible annular soil mass 3 at a preset depth, based on testing needs. It then combines a force application module and an unfolding shear module 1 to achieve in-situ testing of the collapsible soil mass without disturbing it, preserving its original structure. Furthermore, it enables shear strength testing of collapsible soil masses at different depths, thus reflecting the true condition of deep soil with high accuracy, greatly meeting the needs of engineering design and disaster management. Simultaneously, the testing device of this invention is simple, low-cost, and easy to operate.

[0050] To ensure that the force application module can apply a uniform and minimally damaging horizontal normal force to the collapsible annular soil 3, the force application module of this embodiment includes a limiting cylinder 4 and an airbag 5.

[0051] The limiting cylinder 4 is fixedly installed inside the test hole 2 and is at the same horizontal plane as the collapsible annular soil 3;

[0052] The airbag 5 is fixedly installed around the outer wall of the limiting cylinder 4;

[0053] The unfolded shearing module 1 passes through the limiting cylinder 4 along the axial direction of the limiting cylinder 4. Its unfolded end is in contact with the lower surface of the collapsible annular soil 3 in the unfolded state, and is used to apply a vertically upward shearing force to the collapsible annular soil 3.

[0054] For example, the limiting cylinder 4 of the present invention can be combined with ground equipment and fixed in the test hole 2 by suspension, and is at the same horizontal plane as the collapsible annular soil 3. The limiting cylinder 4 can be a steel cylinder.

[0055] The present invention uses a limiting cylinder 4 to restrict the inward contraction of the airbag 5, providing boundary conditions for the uniform expansion of the airbag 5; the present invention inflates the airbag 5, thereby making it contact the inner wall of the collapsible annular soil 3, and applying a uniform and gentle normal force to the collapsible annular soil 3.

[0056] Furthermore, the structure of the unfolded shearing module 1 of the present invention is as follows: Figure 2 and Figure 3 As shown, it includes an extension rod 11, a shear submodule, and a cable 12;

[0057] One end of the extension rod 11 passes through the force application module along the axial direction of the force application module;

[0058] The shearing submodule is fixedly connected to the extension rod 11 at one end of the force application module;

[0059] The first end of the cable 12 is slidably connected to the extension rod 11, and the second end is fixedly connected to the shear sub-module, which is used to drive the unfolding plate 15 of the shear sub-module to rotate.

[0060] The unfolding shearing module 1 of the present invention can extend into the test hole 2 and the limiting cylinder 4 when the unfolding plate 15 is folded up. After reaching the designated position, the unfolding plate 15 is unfolded, thereby applying a vertically upward shearing force to the collapsible annular soil 3.

[0061] This invention achieves the rotation of the unfolding plate 15 in the shearing submodule by using a cable 12, allowing it to be unfolded or folded. Its structure is simple, and because the first end of the cable 12 is slidably connected to the extension rod 11, pulling the unfolding plate 15 requires minimal effort. In one specific embodiment, the first end of the cable 12 can be connected to a chain extending to the ground, thereby controlling the cable 12 from the ground.

[0062] To achieve a sliding connection between the first end of the cable 12 and the extension rod 11, the unfolding shearing module 1 of the present invention further includes a guide rail 13 and a slider that matches the guide rail 13;

[0063] The guide rail 13 is mounted on the rod body of the extension rod 11;

[0064] The slider is located at the first end of cable 12.

[0065] Furthermore, in this embodiment of the invention, limit blocks are respectively provided at both ends of the guide rail 13 to limit the position of the slider and prevent it from detaching from the guide rail 13.

[0066] In addition to the unfolding plate 15, the shearing submodule of this embodiment of the invention also includes a fixing plate 14;

[0067] The fixing plate 14 is fixedly connected to one end of the extension rod 11 that passes through the force application module; preferably, the center of the fixing plate 14 is fixedly connected to the end of the extension rod 11 that passes through the force application module.

[0068] The edges of the unfolding plate 15 and the fixed plate 14 are rotatably connected;

[0069] The second end of the cable 12 is fixedly connected to the unfolding plate 15.

[0070] The present invention can pull the unfolding plate 15, which is rotatably connected to the fixed plate 14, by means of the cable 12, thereby changing the unfolding state of the unfolding plate 15.

[0071] Furthermore, the number of unfolding plates 15 in this embodiment of the invention can be one or more; when there is one unfolding plate 15, it can be a fan-shaped structure or a circular structure, such as... Figure 4 As shown; when there are multiple unfolding plates 15, the multiple unfolding plates 15 are arranged around the fixed plate 14.

[0072] Since the shearing submodule's unfolding plate 15 bears a large force when a vertically upward shearing force is applied to the collapsible annular soil 3, the shearing submodule also includes a support block 16 to ensure the uniformity of the force applied by the shearing submodule and the stability of the structure.

[0073] The support block 16 is located at the connection between the fixed plate 14 and the unfolding plate 15. Its upper surface is fixedly connected to the lower surface of the fixed plate 14, and its upper surface is also in contact with the lower surface of the unfolding plate 15 when the unfolding plate 15 is unfolded. The present invention utilizes the support block 16 to improve the load-bearing capacity of the shearing submodule and ensure the stability of the structure.

[0074] To facilitate intuitive acquisition of the shear strength of collapsible soil, the present invention also includes a data acquisition module 6 and a display module;

[0075] The input end of the data acquisition module 6 is connected to the force application module and the unfolded shear module 1 respectively, and the output end is connected to the display module. It is used to acquire normal force and shear force and display them on the display unit, so as to intuitively obtain the shear strength of collapsible soil.

[0076] For example, the data acquisition module 6 of this embodiment includes two force sensors for acquiring normal force and shear force respectively. One force sensor is disposed on the outer wall of the airbag 5 and located between the airbag 5 and the inner wall of the collapsible annular soil 3. The other force sensor is disposed on the upper surface of the unfolding plate 15 and located between the unfolding plate 15 and the lower surface of the collapsible annular soil 3.

[0077] The present invention can intuitively display the shear strength of collapsible soil through the data acquisition module 6 and the display module, which greatly improves the convenience.

[0078] A second aspect of the present invention provides a method for in-situ testing of collapsible soil annular shear using the above-described collapsible soil annular shear in-situ testing device, comprising:

[0079] Step 1: Prepare a collapsible annular soil body 3 in the test hole 2. The height of the collapsible annular soil body 3 is h.

[0080] Step 2: Place the force application module inside the test hole 2 and make it at the same horizontal level as the collapsible annular soil 3 to apply a horizontal normal force to the collapsible annular soil 3.

[0081] For example, the limiting cylinder 4 in the force application module is fixed in the test hole 2, and the limiting cylinder 4 is at the same horizontal plane as the collapsible annular soil 3; then the air bladder 5 on the outer wall of the limiting cylinder 4 is continuously inflated, so that it applies a horizontal normal force to the collapsible annular soil 3.

[0082] Step 3: Insert the unfolding plate 15 of the unfolding shear module 1 into the test hole 2. In its unfolded state, the unfolding plate 15 is in contact with the lower surface of the collapsible annular soil 3, and is used to apply a vertically upward shearing force to the collapsible annular soil 3. When the unfolding shear module 1 is inserted into the test hole 2 and the limiting cylinder 4, the unfolding plate 15 needs to be folded up so that it is perpendicular to the fixing plate 14.

[0083] When shearing the soil, a force-applying module applies a normal force to the annular soil mass, pulling the unfolding shear module 1 upward to completely shear the collapsible annular soil mass 3. The normal force (normal stress) and shear force (shear stress) are measured and recorded. At this point, the shear strength parameter value of this collapsible soil layer can be obtained. In a specific embodiment, the obtained shear strength parameter value is as follows: Figure 5 As shown in the figure. The straight line is the fitted line.

[0084] Preferably, a collapsible annular soil mass 3 is prepared within the test hole 2, specifically including:

[0085] Within the preset range above and below the preset elevation in test hole 2, the hole is enlarged to obtain enlarged hole 7 and collapsible annular soil 3.

[0086] The preset range is half the height of the collapsible annular soil body 3.

[0087] For example, if the height of the annular soil mass is h, then the preset range is h / 2.

[0088] The testing method of this invention is simple, easy to operate, and saves time and effort.

[0089] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A device for in-situ testing of circumferential shear in collapsible soil, characterized in that, Includes a force application module and an unfolding shearing module; The force application module is installed at the collapsible annular soil within the test hole and is used to apply a horizontal normal force to the collapsible annular soil. The unfolding shear module is installed inside the test hole. Its unfolded plate is in contact with the lower surface of the collapsible annular soil in the unfolded state, and is used to apply a vertically upward shear force to the collapsible annular soil. The force application module includes a limiting cylinder and an airbag; The limiting cylinder is fixedly installed inside the test hole and is at the same horizontal plane as the collapsible annular soil. The airbag is fixedly disposed around the outer wall of the limiting cylinder; The unfolding shearing module passes through the limiting cylinder along the axial direction of the limiting cylinder, and its unfolded end is in contact with the lower surface of the collapsible annular soil in the unfolded state. The deployable shearing module includes an extension rod, a shearing sub-module, and a cable; One end of the extension rod passes through the force-applying module along the axial direction of the force-applying module; The shearing sub-module is fixedly connected to one end of the extension rod that passes through the force application module; The first end of the cable is slidably connected to the extension rod, and the second end is fixedly connected to the shearing sub-module, which is used to drive the unfolding plate of the shearing sub-module to rotate; The shearing submodule also includes a fixing plate; The fixing plate is fixedly connected to one end of the extension rod that passes through the force application module; The edges of the unfolding plate and the fixed plate are rotatably connected; The second end of the cable is fixedly connected to the unfolding plate.

2. The in-situ circumferential shear testing device for collapsible soil according to claim 1, characterized in that, The unfolding shearing module also includes a guide rail and a slider that matches the guide rail; The guide rail is mounted on the body of the extension rod; The slider is located at the first end of the cable.

3. The in-situ circumferential shear testing device for collapsible soil according to claim 1, characterized in that, The number of the unfolding plates is multiple; The plurality of the unfolding plates are arranged around the fixed plate.

4. The in-situ circumferential shear testing device for collapsible soil according to claim 1 or 3, characterized in that, The shearing submodule also includes a support block; The support block is located at the connection between the fixed plate and the unfolding plate, and its upper surface is fixedly connected to the lower surface of the fixed plate and connected to the lower surface of the unfolding plate, respectively.

5. The in-situ circumferential shear testing device for collapsible soil according to claim 1, characterized in that, It also includes a data acquisition module and a display module; The input end of the data acquisition module is connected to the force application module and the unfolding shearing module, respectively, and the output end is connected to the display module.

6. A method for in-situ testing of circumferential shear in collapsible soil, characterized in that, The in-situ circumferential shear testing device for collapsible soil according to any one of claims 1-5 includes: Prepare collapsible ring-shaped soil within the test well; The force application module is placed inside the test hole and positioned at the same horizontal level as the collapsible annular soil mass to apply a horizontal normal force to the collapsible annular soil mass. The unfolded shear module is inserted into the test hole, and its unfolded plate is in contact with the lower surface of the collapsible annular soil in the unfolded state, so as to apply a vertically upward shear force to the collapsible annular soil.

7. The in-situ circumferential shear test method for collapsible soil according to claim 6, characterized in that, The preparation of a collapsible annular soil mass within the test well specifically includes: The test hole is expanded within a preset range above and below a preset elevation to obtain a collapsible annular soil mass.

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