Soil body-structure rough interface multi-included-angle shear test device and operation method thereof

Abstract

The invention discloses a soil body-structure rough interface multi-included-angle shear test device and an operation method thereof. The test device comprises an upper shear box, a lower shear box, a loading system and a data acquisition instrument, a pressure transfer plate, porous stone, filter paper and a shear sample are arranged in the upper shear box, and a sawtooth shear surface module, a corner control assembly and a limiting torque measurement assembly are arranged in the lower shear box; the sawtooth shearing surface module is provided with sawtooth patterns and guide ribs, the corner control assembly is provided with a deflection angle guide groove, a suspension circular truncated cone and a torsion-resisting sector ring, and the limiting torque measurement assembly comprises a circular truncated cone limiting groove, a sector ring limiting groove, a tapered roller bearing, a miniature pressure sensor and a spiral pre-pressing structure; the loading system comprises a horizontal loading system and a vertical loading system. According to the device and the method, diversified interface rough grain inclination angles can be simulated, the sawtooth grain trend is kept constant in the shearing period, the interface shearing torque is accurately tested, and reliable support can be provided for comprehensive evaluation of pile-soil interaction performance in rotary excavating pile and screw pile reinforcing engineering.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical testing, and in particular to a soil-structure rough interface multi-angle shear testing device and an operating method thereof. Background Art

[0002] In pile-reinforced foundation engineering, the premise for foundation reinforcement design and performance evaluation is to clarify the pile-soil interaction characteristics. However, the pile-soil interaction characteristics and their interface parameters often need to be tested through soil-structure shear tests. In fact, affected by factors such as geological conditions, site environment, and construction methods, whether it is a steel pipe pile, reinforced concrete pile or other type of pile, the pile surface is not absolutely smooth and will show a certain degree of roughness. The roughness of the pile-soil interface significantly affects the pile-soil interface interaction characteristics, which in turn affects the prefabricated pile body burying operation, pile foundation bearing capacity and foundation reinforcement effect. Therefore, when conducting the pile-soil interface shear performance test, the fact of the roughness of the pile-soil interface must be considered. For typical cast-in-place pile construction, after the rotary drilling rig is used to make a hole, the soil-cutting blade of the rotary drilling rig is lifted or lowered while rotating, which causes the inner wall of the borehole to form an inclined thread. The inclined thread pattern forms an inclination angle (also called an angle) with the axial direction of the borehole. The size of this angle is related to factors such as the blade rotation rate of the rotary drilling rig, the lifting / lowering rate of the drill rod, and the soil quality of the stratum. The inclined thread of the inner wall of the borehole causes the wall of the cast-in-place pile to form corresponding inclined concave / convex patterns, so a rough interface with an inclination angle is formed between the pile body and the soil body. In addition, since the outer wall of the thread is more conducive to improving the vertical bearing capacity and reinforcement effect of the pile foundation, more and more pile foundation projects use threaded piles, and the interface between the pile body and the soil body is also a typical rough interface with an inclination angle. The inventor found that when the pile-soil interface is a rough interface with an inclination angle, the pile body not only generates axial stress under the action of the upper vertical load, but also torsional stress. The strength of this torsional effect is related to factors such as soil layer characteristics, thread protrusion height, thread inclination angle and its spacing. How to measure and calculate the torsional stress of a pile with a rough interface at an angle and to accurately verify the torsional bearing capacity is of great significance to the reasonable design of the pile foundation structure.

[0003] At present, the prior art mainly realizes a simple simulation of a rough interface. However, in the process of realizing the present invention, the inventors found that the prior art still has the following problems:

[0004] (1) The shear surface module is a component used to simulate the rough outer surface of the structure in the interface shear test. The roughness simulation design of its surface directly affects the test results. Furthermore, if the diversified interface performance of the soil-structure is to be studied, a series of shear surface modules with different roughness and a changing shear direction must be selected. The replacement of the shear surface modules thus caused the test operation steps to be complicated and costly. For example, the invention patent application with publication number CN115266405A discloses a shear test device with adjustable interface roughness. It achieves the purpose of different rough interfaces by replacing steel plates with different roughness. A large number of steel plates with different roughness need to be processed, which costs high test and labor costs.

[0005] (2) In the absence of restrictions on the rotation of the shear surface module, the soil will exert a torsional force on the shear surface module during the shearing process, causing the serrations of the shear surface module to move toward the shear direction under the torsion. That is, the inclination angle (angle) between the interface serrations and the shear direction gradually decreases during the shearing process, which will cause the test results of the rough interface shear test with an inclination to be smaller and distorted. At the same time, the current rough interface shear test device has not yet paid attention to the torsional effect generated during the interface shearing process, and has not attempted to measure the torque during the shearing process. Summary of the invention

[0006] The purpose of the present invention is to provide a soil-structure rough interface multi-angle shear test device with the functions of simulating diversified interface roughness, simply adjusting the shear angle, limiting the rotation of the sawtooth shear surface module and monitoring the torsion effect, so as to solve the problems raised in the background technology.

[0007] To achieve the above-mentioned purpose, the present invention provides a multi-angle shear test device for a rough interface of a soil-structure, comprising a shear box, a loading system and a data acquisition instrument; the shear box comprises an upper shear box and a lower shear box, the inner cavity of the upper shear box is provided with a pressure transmission plate, a permeable stone, a filter paper and a shear specimen in sequence from top to bottom, the inner cavity of the lower shear box is provided with a serrated shear surface module, an angle control component and a limit torque measurement component in sequence from top to bottom, the upper surface of the serrated shear surface module is provided with serrated patterns for close contact with the lower surface of the shear specimen, and the lower surface of the serrated shear surface module is provided with guide ribs, The rotation angle control component includes a circular pancake structure, a suspended truncated cone and two anti-torsion fan rings. A plurality of deflection angle guide grooves passing through its geometric center are opened on the upper surface of the circular pancake structure. The suspended truncated cone and the anti-torsion fan ring are arranged at the bottom of the circular pancake structure. The center of the suspended truncated cone coincides with the center of the lower surface of the rotation angle control component. The two anti-torsion fan rings are symmetrically arranged on both sides of the suspended truncated cone. The limit torque measurement component includes a truncated cone limit groove, a fan ring limit groove, a tapered roller bearing, a micro pressure sensor and a spiral preload structure. The truncated cone limit groove and the fan ring limit groove are recessed downward from the upper surface of the lower shear box base. The center of the truncated cone limiting groove coincides with the center of the lower shear box base, and the tapered roller bearing is arranged in the truncated cone limiting groove; there are two fan ring limiting grooves, which are symmetrically arranged on both sides of the truncated cone limiting groove, and each of the two ends of the fan ring limiting groove is respectively provided with a torsion measuring recess, and a horizontal threaded channel penetrating the side wall of the lower shear box is arranged on the side wall of the torsion measuring recess; a micro pressure sensor is correspondingly arranged in each of the torsion measuring recesses; a spiral preloading structure is arranged in each of the horizontal threaded channels, and the spiral preloading structure includes a hollow top screw and a reset spring; the suspended truncated cone is built into the tapered roller The loading system comprises a horizontal loading system and a vertical loading system, wherein the horizontal loading system comprises a shear push motor, a horizontal load sensor and a horizontal displacement sensor, and the top end of the horizontal push rod of the shear push motor is in contact with the lower shear box; the horizontal load sensor is arranged in front of the pushing direction of the upper shear box; the vertical loading system comprises an electrically controlled loading frame, a vertical load sensor and a vertical displacement sensor; the data acquisition instrument is connected to the loading system to transmit the data obtained by monitoring each sensor to a computer terminal.

[0008] Furthermore, the inner cavity cross-sections of the upper shear box and the lower shear box are both circular, and the upper shear box and the lower shear box are fixedly connected by a fixing pin; a directional wheel rail is provided at the bottom of the lower shear box.

[0009] Furthermore, the apex of the sawtooth pattern of the sawtooth shear surface module is flush with the height of the interface between the upper shear box and the lower shear box.

[0010] Furthermore, the anti-torsion fan ring and the suspended truncated cone are respectively embedded in the fan ring limiting groove and the truncated cone limiting groove, and the tapered roller bearing is located between the suspended truncated cone and the truncated cone limiting groove; a gap is provided between the bottom surface of the tapered roller bearing and the bottom surface of the suspended truncated cone and the bottom surface of the truncated cone limiting groove; a gap is also provided between the bottom surface of the pancake structure and the top surface of the base of the lower shear box.

[0011] Furthermore, the serrated shear surface module is a series of test pieces, and the serrations between a series of serrated shear surface modules are arranged as undulating patterns with different tooth depths, tooth pitches, tooth widths, and chamfers combined with each other; by selecting serrated shear surface modules with different undulating patterns, simulation of different interface roughnesses can be achieved; there is one guide rib, and the length direction of the guide rib is consistent with the direction of the serrated pattern.

[0012] Furthermore, the guide ribs are selectively engaged with guide grooves of different deflection angles to achieve various angle settings between the serrations on the serrated shear surface module and the shear direction; the symmetry axis running through the anti-torsion fan ring and the suspended truncated cone is perpendicular to the shear direction.

[0013] Furthermore, the circumferential sides of the serrated shear surface module and the angle control component are not in contact with the inner cavity side walls of the lower shear box, and the angle control component is in contact with the micro pressure sensor and the tapered roller bearing respectively through the torsion-resistant fan ring and the suspended frustum; lubricant is applied on the inner cavity side walls of the upper shear box and the lower shear box and on the interface between the two.

[0014] Furthermore, each of the micro pressure sensors is placed at the top of the corresponding spiral pre-stressing structure and is connected through the corresponding reset spring; the wire of each micro pressure sensor is led out through the hollow inner core channel of the hollow screw-in screw and connected to the corresponding channel on the data acquisition instrument; through the screwing in or out of the hollow screw-in screw and the adjustment of the reset spring, the micro pressure sensor is slightly protruded from the end side wall of the fan ring limiting groove, and is in pressure contact with the top of the hollow screw-in screw and the end of the torsion-resistant fan ring; the initial reading of the micro pressure sensor should be set to 5kPa~10kPa.

[0015] Furthermore, during the shear test, the pressure values ​​of the four micro pressure sensors are read, and the torque T formed can be calculated by the following formula:

[0016]

[0017] In the formula, the pressure values ​​P1 and P2 are the readings of two micro pressure sensors at both ends of one of the fan ring limiting grooves, and the pressure values ​​P3 and P4 are the readings of the micro pressure sensors at both ends of the other fan ring limiting groove; R is the horizontal distance from the central axis of the fan ring limiting groove to the center of the truncated cone limiting groove.

[0018] The present invention also provides an operating method of the soil-structure rough interface multi-angle shear test device as described above, comprising the following steps:

[0019] S1. First, place the lower shear box on the directional wheel rail, remove the debris in the limit torque measurement assembly, apply lubricant in the truncated cone limit groove and the fan ring limit groove, and place the tapered roller bearing in the truncated cone limit groove; then, rotate the hollow top screw counterclockwise to retract each micro pressure sensor into the torque measuring recess on the end side wall of the fan ring limit groove where it is located, and embed the suspended truncated cone and the anti-torsion fan ring of the angle control assembly into the cavity in the middle of the tapered roller bearing and the fan ring limit groove respectively; secondly, according to the angle between the serration trend and the shear direction on the serrated shear surface module preset in the interface shear test, engage the guide rib of the serrated shear surface module on a certain deflection angle guide groove; finally, symmetrically rotate the hollow top screw clockwise to make each micro pressure sensor slightly protrude from the end side wall of the fan ring limit groove where it is located, and make pressure contact with the top of the hollow top screw and the end of the anti-torsion fan ring until the initial readings of all micro pressure sensors are the same;

[0020] S2. Apply lubricant on the upper surface of the lower shear box, align the upper shear box with the lower shear box, insert the fixing pin, evenly apply lubricant on the inner walls of the upper and lower shear boxes, clamp the casing with the same inner cavity size as the upper shear box on the upper shear box, and ensure that the inner cavity of the casing is aligned with the inner cavity of the upper shear box; weigh the soil of the specified mass, pour it into the inner cavity of the shear box, use the T-type sample press matched with the casing to compact the soil to the specified height to form a shear sample, then remove the T-type sample press and the casing in turn, and place filter paper, permeable stone and pressure transfer plate in turn on the upper surface of the shear sample;

[0021] S3. Adjust the horizontal loading system so that the rear side of the lower shear box in the pushing direction just contacts the horizontal push rod of the shear pushing motor, and set the readings of the horizontal displacement sensor and the horizontal load sensor to zero; align the force transmission rod of the electric control loading frame with the central groove on the contact pressure transmission plate, install the vertical displacement sensor and the vertical load sensor, and set the readings of the vertical displacement sensor and the vertical load sensor to zero;

[0022] S4. Control the vertical load sensor on the electronically controlled loading frame through a computer terminal to apply a preset vertical pressure or a vertical pressure required by relevant specifications and standards;

[0023] S5, after applying vertical pressure, remove the fixing pin and start shearing again, and collect data from each sensor in real time;

[0024] S5. After the shearing is completed, adjust the vertical load sensor reading to zero, remove the vertical pressure, ensure that the force transmission rod of the electronically controlled loading frame is separated from the pressure transmission plate, remove the pressure transmission plate, the permeable stone and the upper shear box in turn, and check the shear morphology of the interface between the shear specimen and the serrated shear surface module; unscrew the hollow top screw counterclockwise to reduce the reading of each micro pressure sensor to zero; then disassemble the lower shear box and the serrated shear surface module, the angle control component and the limit torque measurement component in its inner cavity in turn, clean and dry the components of the test device, organize and analyze the test data, and obtain the change curves of the shear stress, normal displacement and torque of the soil-structure interface with the shear displacement;

[0025] S6. Repeat steps S1 to S5 to carry out the next set of tests.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) Diversified angles of interface roughness

[0028] The present invention considers the phenomenon that there is an angle between the direction of the rough texture of the interface and the shear direction, and splits the traditional interface roughness simulation structure into two structures, namely, a sawtooth shear surface module and an angle control component. Compared with the traditional interface roughness simulation structure, the sawtooth shear surface module in the present invention is thinner and lighter, and only one angle control component is required, so the material consumption is significantly reduced, saving the test cost; in addition, a plurality of deflection angle guide grooves are arranged on the upper surface of the angle control component, and the initial angle between the direction of the sawtooth texture on the sawtooth shear surface module and the shear direction is changed from 0 to 90° by selecting different deflection angle guide grooves to engage the guide ribs, thereby more realistically simulating the actual situation that the concave and convex textures on the surface of the structure are inclined to the shear direction of the structure-soil interface, solving the problem that the angle of the direction of the rough texture of the interface cannot be considered in the traditional test device or the problem that as many interface roughness simulation structures as the angles considered must be made.

[0029] (2) Keep the serrations constant during shearing

[0030] The present invention innovatively arranges a torsion-resistant fan ring on the lower surface of the angle control component, and arranges a fan ring limiting groove in the base of the lower shear box. The engagement of the torsion-resistant fan ring with the fan ring limiting groove can avoid rotation of the angle control component and the serrated shear surface module during shearing, thereby solving the problem of small and distorted shear stress test values ​​and ensuring that the shear stress test results are reliable.

[0031] (3) Accurate measurement and control of interface shear torque

[0032] Taking into account that conventional interface shear tests ignore the torsion effect generated during the shearing process, the present invention not only avoids the shear stress test error caused by the torsion effect through the above-mentioned angle control component, but also pays attention to the torque formed by the torsion effect. A torsion measuring recess is provided at the end of the fan ring limit groove, and a micro pressure sensor is built in to innovatively measure the pressure generated by the torsion, and then calculate the torque. In addition, in terms of the structure to reduce the torque error, a tapered roller bearing is placed in the truncated cone limit groove of the limit torque measurement component, which greatly reduces the friction resistance between the suspended truncated cone and the truncated cone limit groove, and makes the angle control component suspended without contacting the lower shear box, and the torsion fan ring only contacts the micro pressure sensor; in addition, lubricant is applied between the inner walls of the upper and lower shear boxes and the interface between the components to avoid the friction resistance caused by the contact with the soil or the components. The above-mentioned structural design of the present invention can obtain accurate torque values.

[0033] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0035] Figure 1 The schematic diagram of the overall three-dimensional structure of the test device according to one embodiment of the present invention is shown in FIG. Figure 1 (a) is a three-dimensional image from the front. Figure 1 (b) is a three-dimensional image from the oblique rear;

[0036] Figure 2 A schematic diagram of a cross-sectional structure of a shear box according to an embodiment of the present invention;

[0037] Figure 3 Schematic diagram of a sawtooth shearing surface module according to an embodiment of the present invention, wherein Figure 3 (a) is a three-dimensional graph, Figure 3 (b) is a cross-sectional view;

[0038] Figure 4 FIG. 1 is a schematic diagram of a corner control component according to an embodiment of the present invention, wherein Figure 4 (a) is a three-dimensional graph, Figure 4 (b) is a top view. Figure 4 (c) is a bottom view;

[0039] Figure 5 Schematic diagram of the limit torque measuring assembly in the lower shear box according to an embodiment of the present invention, wherein Figure 5 (a) is a three-dimensional graph, Figure 5 (b) is a top view;

[0040] Figure 6 FIG. 1 is a schematic diagram of a spiral preloading structure and a micro pressure sensor according to an embodiment of the present invention, wherein Figure 6 (a) is a three-dimensional graph, Figure 6 (b) is a cross-sectional view;

[0041] Figure 7 A schematic diagram of channel wiring details on a data acquisition device according to an embodiment of the present invention;

[0042] Among them, 1-shear box; 1.1-upper shear box; 1.2-lower shear box; 2-loading system; 2.1-horizontal loading system; 2.2-vertical loading system; 3-data acquisition instrument; 4-pressure transmission plate; 4.1-center groove; 5-permeable stone; 6-filter paper; 7-shear specimen; 8-fixing pin; 9-serrated shear surface module; 10-angle control component; 11-limited torque measurement component; 12-directional wheel rail; 13-serrated pattern; 14-guide rib; 15-pie structure; 16-deflection angle guide groove; 17-suspended truncated table; 18-torsion fan ring; 19-Front table limit groove; 20-Fan ring limit groove; 21.1, 21.2, 21.3, 21.4-Micro pressure sensor; 22.1, 22.2, 22.3, 22.4-Spiral preload structure; 23-Tapered roller bearing; 24-Torsion measuring recess; 25-Horizontal threaded channel; 26-Hollow screw-in bolt; 27-Reset spring; 28-Shear push motor; 29-Horizontal load sensor; 30-Horizontal displacement sensor; 31-Electronic control loading frame; 32-Vertical load sensor; 33-Vertical displacement sensor; 34-Computer terminal. DETAILED DESCRIPTION

[0043] The present invention will be described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0044] See also Figures 1 to 7 This embodiment provides a soil-structure rough interface multi-angle shear test device, including a shear box 1, a loading system 2 and a data acquisition device 3; the specific structure is as follows:

[0045] The shear box 1 includes an upper shear box 1.1 and a lower shear box 1.2; the inner cavity of the upper shear box 1.1 is provided with a pressure transmission plate 4, a permeable stone 5, a filter paper 6 and a shear specimen 7 arranged in sequence from top to bottom for transmitting the load of the electric control loading frame 31. The inner cavity of the lower shear box 1.2 is provided with a serrated shear surface module 9, an angle control component 10 and a limit torque measurement component 11 arranged in sequence from top to bottom. The serrated shear surface module 9, the angle control component 10 and the limit torque measurement component 11 are made of corrosion-resistant materials, preferably stainless steel. The upper surface of the serrated shear surface module 9 is provided with a serrated pattern 13 representing the interface roughness, and the lower surface of the serrated shear surface module 9 is provided with a guide rib 14. The upper surface of the serrated shear surface module 9 is in close contact with the lower surface of the shear specimen 7. The rotation angle control component 10 includes a circular cake structure 15, a suspended truncated cone 17 and a torsion-blocking fan ring 18. The upper surface of the circular cake structure 15 is provided with a plurality of deflection angle guide grooves 16 passing through its geometric center. The suspended truncated cone 17 and the torsion-blocking fan ring 18 are arranged at the bottom of the circular cake structure 15. The center of the suspended truncated cone 17 coincides with the center of the lower surface of the rotation angle control component 10. There are two torsion-blocking fan rings 18, which are symmetrically arranged on both sides of the suspended truncated cone 17. Two torsion-blocking fan rings 18 are arranged in this structural setting, which can prevent the eccentricity and tilting of the shearing sample 7 during the shearing process, and ensure the accuracy of the torque test. The limit torque measurement component 11 is arranged in the base of the lower shear box 1.2, including a truncated cone limiting groove 19, a fan ring limiting groove 20, four micro pressure sensors 21.1, 21.2, 21.3, 21.4, four spiral preloading structures 22.1, 22.2, 22.3, 22.4 and a tapered roller bearing 23. The truncated cone limiting groove 19 and the fan ring limiting groove 20 are recessed downward from the upper surface of the base of the lower shear box 1.2, and the center of the truncated cone limiting groove 19 coincides with the center of the base of the lower shear box 1.2. The tapered roller bearing 23 is arranged in the truncated cone limiting groove 19. There are two fan ring limiting grooves 20, which are symmetrically arranged on both sides of the truncated cone limiting groove 19. The two ends (end faces at both ends in the length direction) of each fan ring limiting groove 20 are provided with a torsion measuring recess 24. A horizontal threaded channel 25 penetrating the side wall of the lower shear box 1.2 is vertically arranged on the side wall of the torsion measuring recess 24; four micro pressure sensors 21.1, 21.2, 21.3, and 21.4 are respectively placed in the corresponding torsion measuring recess 24; four spiral preloading structures 22.1, 22.2, 22.3, and 22.4 are respectively arranged in the corresponding horizontal threaded channels 25, and each spiral preloading structure is composed of a hollow top screw 26 and a reset spring 27. The top of the hollow top screw 27 is provided with a receiving groove, one end of the reset spring 27 is arranged in the receiving groove, and the other end is used to connect with the micro pressure sensor. The suspended truncated cone 17 is built into the cavity in the middle of the tapered roller bearing 23 and is in close contact.The loading system 2 includes a horizontal loading system 2.1 and a vertical loading system 2.2. The horizontal loading system 2.1 includes a shearing push motor 28, a horizontal load sensor 29 and a horizontal displacement sensor 30. The top end of the horizontal push rod of the shearing push motor 28 contacts the lower shear box 1.2, and is used to push the lower shear box 1.2 to move horizontally for shearing. The horizontal load sensor 29 is arranged in front of the pushing direction of the upper shear box 1.1, and is used to test the shear stress during the shearing process. The horizontal displacement sensor 30 is used to measure the shear displacement of the lower shear box 1.2. The vertical loading system 2.2 includes an electric control loading frame 31, a vertical load sensor 32 and a vertical displacement sensor 33. The electric control loading frame 31 applies vertical pressure to the pressure transmission plate 4 through its force transmission rod, and uses the vertical load sensor 32 to control the vertical pressure value. The vertical displacement sensor 33 is used to measure the normal displacement of the pressure transmission plate 4 during the application of vertical pressure and shearing. The data acquisition instrument 3 is connected to the loading system 2, and transmits the data obtained by monitoring each sensor to the computer terminal 34.

[0046] In a specific embodiment, the inner cavity cross-sections of the upper shear box 1.1 and the lower shear box 1.2 are both circular, and the upper shear box 1.1 and the lower shear box 1.2 can be fixed by a fixing pin 8 to ensure that their inner cavities are aligned. A directional wheel track 12 is provided at the bottom of the lower shear box 1.2 to ensure that the lower shear box 1.2 is stuck on the directional wheel track 12 and always moves along the shearing direction. The apex of the serration 13 of the serration shear surface module 9 is flush with the height of the interface between the upper shear box 1.1 and the lower shear box 1.2 to ensure that the shear surface occurs at the apex of the serration 13.

[0047] In a specific embodiment, the anti-torsion fan ring 18 and the suspended truncated cone 17 are respectively embedded in the fan ring limiting groove 20 and the truncated cone limiting groove 19, ensuring that the center of the angle control component 10 always coincides with the center of the inner cavity of the lower shear box 1.2; the tapered roller bearing 23 is arranged between the suspended truncated cone 17 and the truncated cone limiting groove 19, and the inner roller of the tapered roller bearing 23 can convert the sliding friction between the suspended truncated cone 17 and the truncated cone limiting groove 19 into rolling friction, thereby reducing the influence on the torsion during the shearing process. Preferably, the gap between the bottom surface of the tapered roller bearing 23 and the bottom surface of the suspended truncated cone 17 and the bottom surface of the truncated cone limiting groove 19 is not less than 0.3mm; the gap between the bottom surface of the pancake structure 15 of the angle control component 10 and the top surface of the base of the lower shear box 1.2 is not less than 0.5mm, so as to eliminate the torque loss caused by the contact friction between the angle control component 10 and the bottom of the lower shear box 1.2.

[0048] In a specific embodiment, the sawtooth shear surface module 9 is a series of test parts, and a specific sawtooth shear surface module 9 can be selected according to the shear test requirements. The sawtooth pattern 13 between a series of sawtooth shear surface modules 9 is set as an undulating pattern with different tooth depths, tooth pitches, tooth widths, and chamfers. During the test, by selecting sawtooth shear surface modules 9 with different undulating patterns, simulation of different interface roughness can be achieved. Among them, there is one guide rib 14 under the sawtooth shear surface module 13, and the length direction of the guide rib 14 is consistent with the direction of the sawtooth pattern 13. The guide rib 14 is selected to engage with the guide grooves 16 with different deflection angles to achieve a variety of angle settings between the direction of the sawtooth pattern 13 on the sawtooth shear surface module 9 and the shear direction, thereby simulating the various interface roughness pattern direction inclination angles existing in actual engineering. The symmetry axis passing through the anti-torsion fan ring 18 and the suspended truncated cone 17 is perpendicular to the shearing direction. The anti-torsion fan ring 18 is engaged with the fan ring limiting groove 20 to limit the rotation of the angle control component 10, and then limit the rotation of the sawtooth shear surface module 9 during the shearing process, ensuring that the direction of the sawtooth pattern 13 remains unchanged during the shearing process. Specifically, the guide rib 14 in the structural setting has the following functions: (1) controlling the angle: by engaging with the deflection angle guide groove 16 on the angle control module 10, different angle settings can be achieved; (2) playing a limiting role: ensuring that the sawtooth shear module 9 does not rotate during the shearing process, and then the angle remains unchanged, and the test results are not distorted; (3) transmitting the torsion effect: transmitting the torsion effect formed by shearing to the angle control module 10, and then transmitting to and passing through the micro pressure sensor of the limiting torque measurement component 11 to measure the pressure change and calculate the torque.

[0049] In a specific embodiment, after the serrated shear surface module 9 and the angle control component 10 are assembled, they do not contact the inner cavity side wall of the lower shear box 1.2 to avoid torque loss caused by contact friction. The angle control component 10 only contacts the four micro pressure sensors 21.1, 21.2, 21.3, 21.4 and the tapered roller bearing 23 through the anti-torsion fan ring 18 and the suspended truncated cone 17, so that the torsional force generated during the shearing process is measured by the four micro pressure sensors 21.1, 21.2, 21.3, 21.4 through the anti-torsion fan ring 18. The inner cavity side walls and interfaces of the upper shear box 1.1 and the lower shear box 1.2 are coated with lubricant, which will further reduce the influence of contact friction on shear stress and torque.

[0050] In a specific embodiment, four micro pressure sensors 21.1, 21.2, 21.3, 21.4 are respectively placed at the top of four spiral pre-stressing structures 22.1, 22.2, 22.3, 22.4 and are connected by a reset spring 27. The wires of the micro pressure sensors 21.1, 21.2, 21.3, 21.4 are led out through the hollow inner core channel of the hollow top screw 26 and connected to the corresponding channels on the data acquisition instrument 3; the micro pressure sensors 21.1, 21.2, 21.3, 21.4 are pushed by the screwing in or out of the hollow top screw 26 and the adjustment of the reset spring 27, so that they are slightly protruding from the end side wall of the fan ring limiting groove 20, and are in pressure contact with the top of the hollow top screw 26 and the end of the anti-torsion fan ring 18. The four micro pressure sensors 21.1, 21.2, 21.3, 21.4 have the same initial reading, and the initial reading is preferably adjusted to 5kPa~10kPa.

[0051] like Figure 7 As shown, the nine corresponding channels on the data acquisition instrument 3 are respectively connected to the micro pressure sensors 21.1, 21.2, 21.3, 21.4, the vertical displacement sensor 33, the horizontal displacement sensor 30, the vertical load sensor 32, the horizontal load sensor 29 and the computer terminal 34, so that the test data measured by each sensor is transmitted to the computer terminal 34 through the data acquisition instrument 3.

[0052] When there is an angle between the sawtooth pattern 13 on the upper surface of the sawtooth shearing module 9 and the shearing direction, the shearing specimen 7 will produce a torsional effect on the sawtooth shearing module 9 during the shearing process. The torsional effect is transmitted to the angle control component 10 through the engagement of the guide rib 14 and the deflection angle guide groove 16, and then to the anti-torsion fan ring 18, and then contact pressure is generated on the four micro pressure sensors. The pressure values ​​of the four micro pressure sensors 21.1, 21.2, 21.3, and 21.4 are read, and the torque T can be calculated by the following formula:

[0053]

[0054] Wherein, the pressure values ​​P1 and P2 are the readings of the micro pressure sensors 21.1 and 21.2 arranged at the two ends of one of the sector ring limiting grooves 20, and the pressure values ​​P3 and P4 are the readings of the micro pressure sensors 21.3 and 21.4 arranged at the two ends of the other sector ring limiting groove 20; R is the horizontal distance from the central axis of the sector ring limiting groove 20 to the center of the truncated cone limiting groove 19. When processing torque data, it is advisable to use a chart with the same horizontal axis as the shear displacement to obtain the torque value when the shear stress reaches the maximum value and the maximum torque value.

[0055] The present invention also provides an operating method of a soil-structure rough interface multi-angle shear test device, comprising the following steps:

[0056] S1. First, place the lower shear box on the directional wheel rail 12, remove the debris in the limit torque measuring assembly 11, apply lubricant in the truncated cone limit groove 19 and the fan ring limit groove 20, and place the tapered roller bearing 23 in the truncated cone limit groove 19; then, rotate the hollow top screw 26 counterclockwise, stretch the reset spring 27, and then pull the micro pressure sensors 21.1, 21.2, 21.3, 21.4, so that the micro pressure sensors 21.1, 21.2, 21.3, 21.4 are respectively retracted to the torque measuring concave portion 24 of the end side wall of the fan ring limit groove 20 where they are located, and the suspended truncated cone 17 and the anti-torsion fan ring 18 of the angle control assembly 10 are respectively embedded in the cavity in the middle of the tapered roller bearing 23 and the fan ring limit groove 20; secondly, according to the interface shear The angle between the direction of the sawtooth pattern 13 on the sawtooth shear surface module 9 preset in the cutting test and the shear direction is adjusted, and the guide rib 14 of the sawtooth shear surface module 9 is engaged with a certain deflection angle guide groove 16; finally, the hollow top screw 26 is symmetrically screwed in clockwise to squeeze the reset spring 27, and then the micro pressure sensors 21.1, 21.2, 21.3, and 21.4 are pushed, so that the micro pressure sensors 21.1, 21.2, 21.3, and 21.4 are respectively slightly protruded from the end side walls of the fan ring limiting groove 20 where they are located, and the pressure contacts the top of the hollow top screw 26 and the end of the anti-torsion fan ring 18 until the four micro pressure sensors 21.1, 21.2, 21.3, and 21.4 have the same initial reading, and the initial reading is preferably within the range of 5kPa to 10kPa.

[0057] S2. Apply lubricant on the upper surface of the lower shear box 1.2, align the upper shear box 1.1 with the lower shear box 1.2, insert the fixing pin 8, evenly apply lubricant on the inner walls of the upper and lower shear boxes, and clamp the casing with the same inner cavity size as the upper shear box 1.1 into the upper shear box 1.1 to ensure that the inner cavity of the casing is aligned with the inner cavity of the upper shear box 1.1. Weigh the soil of the specified mass and pour it into the inner cavity of the shear box 1, and use the T-type sample press matched with the casing to compact the soil to the specified height to form a shear sample 7, then remove the T-type sample press and the casing in turn, and place filter paper 6, permeable stone 5 and pressure transfer plate 4 on the surface of the shear sample 7 in turn;

[0058] S3. By adjusting the horizontal loading system 2.1, ensure that the rear side of the lower shear box 1.1 in the pushing direction is just in contact with the horizontal push rod of the shear pushing motor 28, and set the readings of the horizontal displacement sensor 30 and the horizontal load sensor 29 to zero; align the force transmission rod of the electric control loading frame 31 with the central groove 4.1 on the contact pressure transmission plate 4, install the vertical displacement sensor 33 and the vertical load sensor 32, and set the readings of the vertical displacement sensor 33 and the vertical load sensor 32 to zero.

[0059] S4. Control the vertical load sensor 32 on the electric loading frame 31 through the computer terminal 32 to apply a preset vertical pressure or a vertical pressure required by relevant specifications and standards.

[0060] S5. After applying vertical pressure, remove the fixing pin 8 and start shearing again, and collect the data of each sensor in real time; when the shear stress reading reaches stability or decreases significantly, it means that the shear sample 7 has been sheared; when the shear stress reading continues to increase, the shear displacement should be no less than 6mm, and the data of all sensors during the shearing process are recorded in real time.

[0061] S5. After the shearing is completed, adjust the vertical load sensor 32 to read zero, remove the vertical pressure, ensure that the force transmission rod of the electric control loading frame 31 is separated from the pressure transmission plate 4, remove the pressure transmission plate 4, the permeable stone 5 and the upper shear box 1.1 in turn, and check the shear morphology of the interface between the shear specimen 7 and the serrated shear surface module 9; unscrew the hollow top screw 26 counterclockwise to reduce the readings of the micro pressure sensors 21.1, 21.2, 21.3, and 21.4 to zero; then disassemble the lower shear box 1.2 and the serrated shear surface module 9, the angle control component 10 and the limit torque measurement component 11 in its inner cavity in turn, clean and dry the components of the test device, organize and analyze the test data, and obtain the change curves of the shear stress, normal displacement and torque of the soil-structure interface with the shear displacement.

[0062] S6. Repeat steps S1 to S5 to carry out the next set of tests.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A soil-structure rough interface multi-angle shear test device, characterized in that: It includes a shear box, a loading system and a data acquisition instrument; the shear box includes an upper shear box and a lower shear box, the inner cavity of the upper shear box is provided with a pressure transmission plate, a permeable stone, filter paper and a shear sample in sequence from top to bottom, the inner cavity of the lower shear box is provided with a serrated shear surface module, an angle control component and a limit torque measurement component in sequence from top to bottom, the upper surface of the serrated shear surface module is provided with serrated patterns for close contact with the lower surface of the shear sample, the lower surface of the serrated shear surface module is provided with guide ribs, the angle control component includes a round cake structure, a suspended truncated cone and two torsion-resistant fan rings, A plurality of deflection angle guide grooves passing through its geometric center are provided on the upper surface of the pancake structure; the suspended truncated cone and the anti-torsion fan ring are arranged at the bottom of the pancake structure; the center of the suspended truncated cone coincides with the center of the lower surface of the angle control component; the two anti-torsion fan rings are symmetrically arranged on both sides of the suspended truncated cone; the position limiting torque measuring component comprises a truncated cone limiting groove, a fan ring limiting groove, a tapered roller bearing, a micro pressure sensor and a spiral preloading structure; the truncated cone limiting groove and the fan ring limiting groove are recessed downward from the upper surface of the lower shear box base; the center of the truncated cone limiting groove coincides with the center of the lower surface of the lower shear box base The centers of the seats coincide, and the tapered roller bearing is arranged in the truncated cone limiting groove; there are two fan ring limiting grooves, which are symmetrically arranged on both sides of the truncated cone limiting groove, and each of the two ends of the fan ring limiting groove is provided with a torsion measuring recess, and a horizontal threaded channel penetrating the side wall of the lower shear box is provided on the side wall of the torsion measuring recess; each of the torsion measuring recesses is correspondingly provided with a micro pressure sensor; each of the horizontal threaded channels is provided with a spiral preloading structure, and the spiral preloading structure includes a hollow top screw and a reset spring; the suspended truncated cone is built into the cavity in the middle of the tapered roller bearing, and is in close contact with the tapered roller bearing; the loading system includes a horizontal loading system and a vertical loading system, the horizontal loading system includes a shear push motor, a horizontal load sensor and a horizontal displacement sensor, the top end of the horizontal push rod of the shear push motor is in contact with the lower shear box; the horizontal load sensor is arranged on the front side of the propulsion direction of the upper shear box; the vertical loading system includes an electrically controlled loading frame, a vertical load sensor and a vertical displacement sensor; the data acquisition instrument is connected to the loading system to transmit the data obtained by monitoring each sensor to the computer terminal.

2. The shear test device according to claim 1, characterized in that: The inner cavity cross-sections of the upper shear box and the lower shear box are both circular, and the upper shear box and the lower shear box are fixedly connected by a fixing pin; a directional wheel rail is arranged at the bottom of the lower shear box.

3. The shear test device according to claim 1, characterized in that: The apex of the sawtooth pattern of the sawtooth shear surface module is flush with the height of the interface between the upper shear box and the lower shear box.

4. The shear test device according to claim 1, characterized in that: The anti-torsion fan ring and the suspended truncated cone are respectively embedded in the fan ring limiting groove and the truncated cone limiting groove, and the tapered roller bearing is located between the suspended truncated cone and the truncated cone limiting groove; a gap is provided between the bottom surface of the tapered roller bearing, the bottom surface of the suspended truncated cone and the bottom surface of the truncated cone limiting groove; a gap is also provided between the bottom surface of the pancake structure and the top surface of the base of the lower shear box.

5. The shear test device according to claim 1, characterized in that: The sawtooth shear surface module is a series of test pieces, and the sawtooth patterns between a series of sawtooth shear surface modules are arranged as undulating patterns with different tooth depths, tooth pitches, tooth widths, and chamfers combined with each other; by selecting sawtooth shear surface modules with different undulating patterns, simulation of different interface roughnesses can be achieved; there is one guide rib, and the length direction of the guide rib is consistent with the direction of the sawtooth pattern.

6. The shear test device according to claim 1, characterized in that: The guide ribs are selectively engaged with guide grooves with different deflection angles to achieve various angle settings between the sawtooth pattern on the sawtooth shear surface module and the shear direction; the symmetry axis running through the torsion-resistant fan ring and the suspended truncated cone is perpendicular to the shear direction.

7. The shear test device according to claim 1, characterized in that: The circumferential sides of the serrated shear surface module and the angle control component are not in contact with the inner cavity side walls of the lower shear box, and the angle control component is in contact with the micro pressure sensor and the tapered roller bearing respectively through the torsion-resistant fan ring and the suspended frustum; lubricant is applied on the inner cavity side walls of the upper shear box and the lower shear box and on the interface between the two.

8. The shear test device according to claim 1, characterized in that: Each of the micro pressure sensors is placed at the top of the corresponding spiral pre-stressing structure and is connected through the corresponding reset spring; the wire of each micro pressure sensor is led out through the hollow inner core channel of the hollow screw-in screw and connected to the corresponding channel on the data acquisition instrument; through the screwing in or out of the hollow screw-in screw and the adjustment of the reset spring, the micro pressure sensor is slightly protruded from the end side wall of the fan ring limiting groove, and is in pressure contact with the top of the hollow screw-in screw and the end of the torsion-resistant fan ring. The initial reading of the micro pressure sensor should be set to 5kPa~10kPa.

9. The shear test device according to claim 1, characterized in that: During the shear test, the pressure values ​​of the four micro pressure sensors are read, and the torque T formed can be calculated by the following formula: In the formula, the pressure values ​​P1 and P2 are the readings of two micro pressure sensors at both ends of one of the fan ring limiting grooves, and the pressure values ​​P3 and P4 are the readings of the micro pressure sensors at both ends of the other fan ring limiting groove; R is the horizontal distance from the central axis of the fan ring limiting groove to the center of the truncated cone limiting groove.

10. A method for operating a shear test device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. First, place the lower shear box on the directional wheel rail, remove the debris in the limit torque measurement assembly, apply lubricant in the truncated cone limit groove and the fan ring limit groove, and place the tapered roller bearing in the truncated cone limit groove; then, rotate the hollow top screw counterclockwise to retract each micro pressure sensor into the torque measuring recess on the end side wall of the fan ring limit groove where it is located, and embed the suspended truncated cone and the anti-torsion fan ring of the angle control assembly into the cavity in the middle of the tapered roller bearing and the fan ring limit groove respectively; again, according to the angle between the serration trend and the shear direction on the serrated shear surface module preset in the interface shear test, engage the guide rib of the serrated shear surface module on a certain deflection angle guide groove; finally, symmetrically rotate the hollow top screw clockwise to make each micro pressure sensor slightly protrude from the end side wall of the fan ring limit groove where it is located, and make pressure contact with the top of the hollow top screw and the end of the anti-torsion fan ring until the initial readings of all micro pressure sensors are the same; S2. Apply lubricant on the upper surface of the lower shear box, align the upper shear box with the lower shear box, insert the fixing pin, evenly apply lubricant on the inner walls of the upper and lower shear boxes, clamp the casing with the same inner cavity size as the upper shear box on the upper shear box, and ensure that the inner cavity of the casing is aligned with the inner cavity of the upper shear box; weigh the soil of the specified mass, pour it into the inner cavity of the shear box, use the T-type sample press matched with the casing to compact the soil to the specified height to form a shear sample, then remove the T-type sample press and the casing in turn, and place filter paper, permeable stone and pressure transfer plate in turn on the upper surface of the shear sample; S3, adjust the horizontal loading system so that the rear side of the lower shear box in the advancing direction just contacts the horizontal push rod of the shear advancing motor, and set the readings of the horizontal displacement sensor and the horizontal load sensor to zero; Align the force transmission rod of the electric control loading frame with the central groove of the contact pressure transmission plate, install the vertical displacement sensor and the vertical load sensor, and set the readings of the vertical displacement sensor and the vertical load sensor to zero; S4. Control the vertical load sensor on the electronically controlled loading frame through a computer terminal to apply a preset vertical pressure or a vertical pressure required by relevant specifications and standards; S5, after applying vertical pressure, remove the fixing pin and start shearing again, and collect data from each sensor in real time; S5. After the shearing is completed, adjust the vertical load sensor reading to zero, remove the vertical pressure, ensure that the force transmission rod of the electronically controlled loading frame is separated from the pressure transmission plate, remove the pressure transmission plate, the permeable stone and the upper shear box in turn, and check the shear morphology of the interface between the shear specimen and the serrated shear surface module; unscrew the hollow top screw counterclockwise to reduce the reading of each micro pressure sensor to zero; then disassemble the lower shear box and the serrated shear surface module, the angle control component and the limit torque measurement component in its inner cavity in turn, clean and dry the components of the test device, organize and analyze the test data, and obtain the change curves of the shear stress, normal displacement and torque of the soil-structure interface with the shear displacement; S6. Repeat steps S1 to S5 to carry out the next set of tests.

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