In-situ combined test device for measuring shear strength and interfacial friction coefficient of soil body

Abstract

The invention discloses an in-situ combined test device for measuring the shear strength and the interface friction coefficient of a soil body, and relates to the technical field of geotechnical engineering test instruments. The device comprises a vane shear test device, an interface friction coefficient test device, a power device and a frame, the vane shear test device comprises a vane head, a hollow shaft lever, a first torque sensor and a first connecting rod, and the interface friction coefficient test device comprises a friction cylinder, a shaft lever, a second torque sensor and a second connecting rod. The shaft rod is arranged in the hollow shaft rod in a penetrating mode, so that the cross plate head and the friction cylinder are independently arranged on the same axis. The power device comprises a first motor and a second motor which are used for driving the cross plate head and the friction cylinder to rotate respectively, independent driving is achieved through a worm and gear transmission mechanism, and meanwhile a third motor is arranged to be matched with the screw rod set to drive the whole test device to ascend and descend in the vertical direction.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering testing instruments, specifically to an in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil. Background Technology

[0002] Soil shear strength and the coefficient of friction between the soil and the structure are important mechanical parameters in geotechnical engineering investigation, foundation design, and marine engineering. Their test results directly affect the stability and safety of engineering structures. Currently, these parameters are typically measured in-situ using in-situ testing methods such as vane shear tests and interfacial friction tests under field conditions.

[0003] Existing vane shear tests typically involve lowering the vane head to a predetermined depth in the soil layer via connecting rods, rotating the vane head at a certain speed, and measuring the torque experienced during rotation to inversely determine the soil's shear strength parameters. Interfacial friction tests, on the other hand, usually employ a friction cylinder structure. The friction cylinder is lowered to a predetermined depth in the soil layer via connecting rods, and its rotation is controlled while measuring the torque experienced, thereby calculating the interfacial friction coefficient between the soil and the outer wall of the friction cylinder.

[0004] In practical engineering applications, due to the different structures and test objects of the two types of test devices, existing technologies typically require separate vane shear tests and interface friction tests. This involves lowering different test devices sequentially into the same borehole to complete the corresponding tests. During the test, both the friction cylinder and the vane head need to be lowered to the target depth segment by segment using multiple connecting rods. After the test is completed, they are pulled out as a whole, and then another test device is used to repeat the above operation.

[0005] The existing testing methods described above have certain shortcomings in practical applications. On the one hand, vane shear tests and interfacial friction tests cannot be performed simultaneously in the same process, resulting in repetitive testing, longer operation time, and increased on-site construction and labor costs. On the other hand, since the two types of tests need to be conducted at different times, it is difficult to ensure that the in-situ conditions corresponding to the two tests are completely consistent, which may affect the comparative analysis of the test results. Therefore, how to improve the efficiency of in-situ testing of soil shear strength and interfacial friction coefficient while ensuring testing accuracy and reliability has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides an in-situ combined testing device for determining soil shear strength and interfacial friction coefficient. This device solves the problem of wasted time and labor costs caused by the inability to simultaneously perform the vane shear test for determining shear strength and the friction cylinder test for determining interfacial friction coefficient. It enables the combined determination of soil shear strength and interfacial friction coefficient, reducing testing time and improving testing efficiency.

[0007] This invention is achieved through the following technical solution: an in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil, comprising: The vane shear test apparatus, the interface friction coefficient test apparatus, the power unit, and the frame; The vane shearing test device includes a vane head, a hollow shaft, a first torque sensor, and a first connecting rod. The lower part of the first torque sensor is connected to the vane head through the hollow shaft, and its upper part is connected to the first connecting rod. The interface friction coefficient testing device includes a friction cylinder, a shaft, a second torque sensor, and a second connecting rod. The lower part of the second torque sensor is connected to the friction cylinder through the shaft, and its upper part is connected to the second connecting rod. The shaft passes through the hollow shaft. The power unit includes a first motor, a second motor, a first worm gear, a first worm, a second worm gear, and a second worm. The first worm is connected to the shaft of the first motor and meshes with the first worm gear. The first worm gear is connected to the first connecting rod to drive the crosshead to rotate. The second worm is connected to the shaft of the second motor and meshes with the second worm gear. The second worm gear is connected to the second connecting rod to drive the friction cylinder to rotate. The first motor, the second motor, the first worm gear, and the second worm gear are all mounted on the frame; The torque data of the vane head and the friction cylinder during rotation are measured by the first torque sensor and the second torque sensor, respectively, so as to realize the in-situ joint determination of soil shear strength and interface friction coefficient at the same depth.

[0008] As a preferred technical solution, the hollow shaft, the first torque sensor, the first connecting rod, and the first worm gear are all hollow structures, with the shaft sequentially inserted therethrough.

[0009] As a preferred technical solution, the crosshead and the friction cylinder are arranged on the same axis in the vertical direction.

[0010] As a preferred technical solution, the first motor and the second motor are controlled independently so that the crosshead and the friction cylinder can rotate synchronously or separately.

[0011] As a preferred technical solution, the frame includes a movable frame and a support frame, and the first motor and the second motor are fixedly mounted on the movable frame.

[0012] As a preferred technical solution, the power unit further includes a third motor, a transmission shaft, a bevel gear set, and a screw rod set. The third motor drives the screw rod set to rotate through the transmission shaft and the bevel gear set, thereby driving the moving frame to rise and fall in the vertical direction.

[0013] As a preferred technical solution, the screw assembly includes a screw and a nut, the nut is fixed on the movable frame, and the upper and lower ends of the screw are fixed to the support frame by a shaft connection.

[0014] As a preferred technical solution, a limit switch is provided between the movable frame and the supporting frame to limit the lifting stroke of the movable frame.

[0015] As a preferred technical solution, the vertical members of the support frame are provided with a scale, and the movable frame is provided with a pointer that cooperates with the scale to indicate the soil penetration depth of the crosshead and the friction cylinder.

[0016] As a preferred technical solution, a monitoring controller is also included. The monitoring controller is electrically connected to the first motor, the second motor, the third motor, the first torque sensor, and the second torque sensor, respectively, and is used to control the test process and collect torque data.

[0017] The beneficial effects of this invention are as follows: By coaxially integrating the vane shear test device and the interface friction coefficient test device in terms of structure, this invention enables the vane head and the friction cylinder to be arranged simultaneously under the same drilling and depth conditions. Furthermore, the hollow shaft and the inner through shaft sleeve structure enable the two test systems to operate independently. This structurally solves the problem of process conflicts caused by the need for the two types of test devices to be lowered and tested in stages in the prior art.

[0018] This invention employs a first motor and a second motor, which are independent of each other, to drive the crosshead and friction cylinder to rotate, and a first torque sensor and a second torque sensor are respectively set up to measure torque. This ensures that the soil shear strength test and the interface friction coefficient test do not interfere with each other in terms of power input and data acquisition, and can synchronously acquire the corresponding test data under the same in-situ working conditions, which is beneficial to improving the accuracy and comparability of the test results.

[0019] This invention enables the entire combined testing device to be raised and lowered vertically by setting up a third motor in conjunction with a screw rod assembly. This allows the crosshead and friction cylinder to be tested continuously or in segments at different depths, thereby meeting the needs of testing soil mechanical parameters at multiple depths under different engineering conditions and expanding the applicability of the device.

[0020] The present invention incorporates auxiliary structures such as limit switches, scales, and pointers within the frame structure, which can effectively limit and intuitively indicate the lifting stroke and soil penetration depth of the device, helping to prevent damage to the device due to misoperation, while improving the safety and ease of operation during on-site testing. Attached Figure Description

[0021] 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.

[0022] Figure 1 This illustration shows a front perspective view of the overall structure of an in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil, provided in an embodiment of the present invention. Figure 2 This diagram illustrates a three-dimensional rear view of the overall structure of an in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil, provided in an embodiment of the present invention. Figure 3 This illustration shows a partial enlarged view of the vane head, friction cylinder, and shaft of an in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil, provided in an embodiment of the present invention. Explanation of reference numerals in the attached drawings: 1. Friction cylinder; 2. Shaft; 3. Crosshead; 4. Hollow shaft; 5. First torque sensor; 6. First connecting rod; 7. First motor; 8. First worm gear; 9. First worm; 10. Second torque sensor; 11. Second motor; 12. Second connecting rod; 13. Second worm gear; 14. Second worm; 15. Moving frame; 16. Nut; 17. Screw; 18. Support frame; 19. Bevel gear set; 20. Drive shaft; 21. Third motor; 22. Monitoring controller. Detailed Implementation

[0023] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0024] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0025] See appendix Figure 1 To be continued Figure 3This embodiment provides an in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil, comprising a vane shear test device, an interfacial friction coefficient test device, a power device, and a frame. The vane shear test device is used for in-situ testing of the shear strength of soil, and the interfacial friction coefficient test device is used for in-situ testing of the frictional properties between soil and the contact interface. The two devices are coaxially integrated in structure but functionally independent, thus enabling combined testing under the same borehole and depth conditions.

[0026] Specifically, the vane shear test device includes a vane head 3, a hollow shaft 4, a first torque sensor 5, and a first connecting rod 6. The vane head 3 is located at the lower end of the device and is used to insert into the soil and perform shearing action with the surrounding soil during rotation. The first torque sensor 5 is located above the vane head 3, and its lower end is connected to the vane head 3 via the hollow shaft 4, so that the torque generated by the vane head 3 during rotation can be transmitted to the first torque sensor 5 and measured in real time. The upper end of the first torque sensor 5 is connected to the first connecting rod 6, which is used to transmit the torque to the upper drive mechanism.

[0027] The interface friction coefficient testing device includes a friction cylinder 1, a shaft 2, a second torque sensor 10, and a second connecting rod 12. The friction cylinder 1 is positioned below or adjacent to the vane head 3, forming a stable contact interface with the soil and generating interface friction during rotation. The friction cylinder 1 is connected to the second torque sensor 10 via the shaft 2, allowing the friction torque generated during rotation to be transmitted to and measured by the second torque sensor 10. The upper end of the second torque sensor 10 is connected to the second connecting rod 12, transmitting the torque to the corresponding drive mechanism. The shaft 2 is vertically aligned and passes through the hollow shaft 4, ensuring that the vane shear testing device and the interface friction coefficient testing device are coaxially arranged on the same axis, while maintaining structural and functional independence.

[0028] In this embodiment, the hollow shaft 4, the first torque sensor 5, the first connecting rod 6, and the first worm gear 8 are all hollow structures, with the shaft 2 passing through them in sequence, thereby ensuring that the interface friction coefficient test device can operate independently without interfering with the operation of the vane shear test device.

[0029] The power unit includes a first motor 7, a second motor 11, a first worm gear 8, a first worm 9, a second worm gear 13, and a second worm 14. The first motor 7 is fixedly mounted on the movable frame 15, and its output shaft is connected to the first worm 9. The first worm 9 meshes with the first worm gear 8, which is fixedly connected to the first connecting rod 6. Thus, when the first motor 7 rotates, it drives the first connecting rod 6, the first torque sensor 5, the hollow shaft 4, and the crosshead 3 to rotate synchronously via worm gear transmission. The second motor 11 is also fixedly mounted on the movable frame 15, and its output shaft is connected to the second worm 14. The second worm 14 meshes with the second worm gear 13, which is connected to the second connecting rod 12. Thus, when the second motor 11 rotates, it drives the second connecting rod 12, the second torque sensor 10, the shaft 2, and the friction cylinder 1 to rotate. Through this structural arrangement, the crosshead 3 and the friction cylinder 1 can be controlled to rotate independently at the same depth, and their rotation processes do not interfere with each other.

[0030] The frame includes a movable frame 15 and a support frame 18. A first motor 7, a second motor 11, a first worm gear 9, and a second worm gear 14 are all fixedly mounted on the movable frame 15. The power unit also includes a third motor 21, a transmission shaft 20, a bevel gear set 19, and a screw assembly. The screw assembly includes a screw 17 and a nut 16. The nut 16 is fixedly mounted at both ends of the movable frame 15. The screw 17 is vertically oriented, and its upper and lower ends are fixed to the support frame 18 via shaft connections. The third motor 21 is fixedly mounted above the support frame 18, and its output shaft is connected to the transmission shaft 20. Both ends of the transmission shaft 20 are connected to the upper ends of the screw 17 via the bevel gear set 19.

[0031] By controlling the rotation of the third motor 21, the transmission shaft 20 drives the screw 17 to rotate via the bevel gear set 19. The threaded engagement between the screw 17 and the nut 16 causes the moving frame 15 to rise or fall vertically relative to the support frame 18, thereby raising and lowering the vane shear test device and the interface friction coefficient test device fixed on the moving frame 15 as a whole. A limit switch is provided between the moving frame 15 and the support frame 18 to limit the lifting stroke of the moving frame 15 and prevent damage to the device due to excessive lifting. The vertical components of the support frame 18 are provided with scales, and the moving frame 15 is provided with pointers that cooperate with the scales. The relative position of the pointers and the scales can visually indicate the penetration depth of the vane head 3 and the friction cylinder 1.

[0032] In this embodiment, a monitoring controller 22 is also provided. The monitoring controller 22 is electrically connected to the first motor 7, the second motor 11, the third motor 21, the first torque sensor 5, and the second torque sensor 10, respectively, and is used to centrally control the test process and collect and record torque data.

[0033] During the experiment, the entire experimental setup is first fixed in the desired testing position, and the frame is leveled. Then, the monitoring controller 22 controls the third motor 21 to rotate, causing the moving frame 15 to rise to the top position under the action of the screw rod assembly. The friction cylinder 1, shaft 2, crosshead 3, hollow shaft 4, first torque sensor 5, first connecting rod 6, first worm gear 8, second torque sensor 10, second connecting rod 12, and second worm gear 13 are installed sequentially according to the structure shown in the attached diagram. The lengths of the hollow shaft 4 and shaft 2 are adjusted according to the required test depth. Afterwards, the monitoring controller 22 controls the third motor 21 to rotate in the opposite direction, causing the moving frame 15 to descend until the friction cylinder 1 and crosshead 3 reach the predetermined test depth.

[0034] Once the device reaches the predetermined depth, the monitoring controller 22 controls the rotation of the first motor 7 and the second motor 11. The first motor 7 drives the crosshead 3 to rotate via the first worm 9 and the first worm wheel 8, while the second motor 11 drives the friction cylinder 1 to rotate via the second worm 14 and the second worm wheel 13. During rotation, the first torque sensor 5 and the second torque sensor 10 measure the torque on the crosshead 3 and the friction cylinder 1 in real time. Based on the measured torque data and the structural parameters of the crosshead 3 and the friction cylinder 1, the shear strength and interfacial friction coefficient of the soil at the corresponding depth can be calculated, thus achieving in-situ joint determination of the soil shear strength and interfacial friction coefficient.

[0035] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil, characterized in that, include: The vane shear test apparatus, the interface friction coefficient test apparatus, the power unit, and the frame; The vane shear test device includes a vane head (3), a hollow shaft (4), a first torque sensor (5) and a first connecting rod (6). The lower part of the first torque sensor (5) is connected to the vane head (3) through the hollow shaft (4), and its upper part is connected to the first connecting rod (6). The interface friction coefficient testing device includes a friction cylinder (1), a shaft (2), a second torque sensor (10), and a second connecting rod (12). The lower part of the second torque sensor (10) is connected to the friction cylinder (1) through the shaft (2), and its upper part is connected to the second connecting rod (12). The shaft (2) is inserted into the hollow shaft (4). The power unit includes a first motor (7), a second motor (11), a first worm wheel (8), a first worm (9), a second worm wheel (13), and a second worm (14). The first worm (9) is connected to the shaft of the first motor (7) and meshes with the first worm wheel (8). The first worm wheel (8) is connected to the first connecting rod (6) to drive the crosshead (3) to rotate. The second worm (14) is connected to the shaft of the second motor (11) and meshes with the second worm wheel (13). The second worm wheel (13) is connected to the second connecting rod (12) to drive the friction cylinder (1) to rotate. The first motor (7), the second motor (11), the first worm (9) and the second worm (14) are all fixedly mounted on the movable frame (15); The torque data of the crosshead (3) and the friction cylinder (1) during rotation are measured by the first torque sensor (5) and the second torque sensor (10) respectively, so as to realize the in-situ joint determination of soil shear strength and interface friction coefficient at the same depth.

2. The in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil according to claim 1, characterized in that: The hollow shaft (4), the first torque sensor (5), the first connecting rod (6) and the first worm gear (8) are all hollow structures, and the shaft (2) is inserted therethrough.

3. The in-situ combined testing device for determining the shear strength and interfacial friction coefficient of soil according to claim 1, characterized in that: The crosshead (3) and the friction cylinder (1) are arranged on the same axis in the vertical direction.

4. The in-situ combined testing apparatus for determining the shear strength and interfacial friction coefficient of soil according to claim 1, characterized in that: The first motor (7) and the second motor (11) are controlled independently so that the crosshead (3) and the friction cylinder (1) can rotate synchronously or separately.

5. The in-situ combined testing apparatus for determining the shear strength and interfacial friction coefficient of soil according to claim 1, characterized in that: The frame includes a movable frame (15) and a support frame (18), and the first motor (7) and the second motor (11) are fixedly installed on the movable frame (15).

6. The in-situ combined testing apparatus for determining the shear strength and interfacial friction coefficient of soil according to claim 5, characterized in that: The power unit also includes a third motor (21), a transmission shaft (20), a bevel gear set (19), and a screw rod set. The third motor (21) drives the screw rod set to rotate through the transmission shaft (20) and the bevel gear set (19) to drive the moving frame (15) to rise and fall in the vertical direction.

7. The in-situ combined testing apparatus for determining the shear strength and interfacial friction coefficient of soil according to claim 6, characterized in that: The screw assembly includes a screw (17) and a nut (16). The nut (16) is fixed on the movable frame (15), and the upper and lower ends of the screw (17) are fixed to the support frame (18) by a shaft connection.

8. The in-situ combined testing apparatus for determining the shear strength and interfacial friction coefficient of soil according to claim 6, characterized in that: A limit switch is provided between the movable frame (15) and the support frame (18) to limit the lifting stroke of the movable frame (15).

9. The in-situ combined testing apparatus for determining the shear strength and interfacial friction coefficient of soil according to claim 5, characterized in that: The vertical members of the support frame (18) are provided with scales, and the movable frame (15) is provided with pointers that cooperate with the scales to indicate the soil penetration depth of the crosshead (3) and the friction cylinder (1).

10. The in-situ combined testing apparatus for determining the shear strength and interfacial friction coefficient of soil according to claim 1, characterized in that: It also includes a monitoring controller (22), which is electrically connected to the first motor (7), the second motor (11), the third motor (21), the first torque sensor (5), and the second torque sensor (10) respectively, and is used to control the test process and collect torque data.

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