Visual contact surface direct shear apparatus considering seepage and structure coupling effect

Abstract

The invention discloses a visual contact surface direct shear apparatus considering a seepage and structure coupling effect. The visual contact surface direct shear apparatus comprises a main body frame, a normal force applying system, a shear force applying system, an electric appliance integrated circuit box, a shear box system, a seepage control system, an image acquisition system, an information monitoring and acquisition system and a sliding seat system, the shear box system is arranged on the sliding seat system, the sliding seat system is fixed at the bottom of the inner side of the main body frame, the normal force applying system and the electric appliance integrated circuit box are arranged at the upper part of the main body frame, the shear force applying system is arranged at the right lower part of the main body frame, and the seepage control system is arranged at the right upper part of the main body frame. The image acquisition system is arranged at the front part of the main body frame, and the shooting direction directly faces the shear box system. The device has the test capacity of independently applying normal static and dynamic loads and tangential static loads, can simulate the seepage action of underground water in the sample shearing process, has the function of observing the mechanical properties of a contact surface in a macro-micro manner, and can be used for carrying out equal-section and variable-section direct shear tests.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical testing equipment, in particular to a visual contact surface direct shear instrument taking into account the coupling effect of seepage and structure. Background Art

[0002] In geotechnical engineering, we often encounter contact interfaces between different materials, such as soil-concrete structure, rock-concrete structure, soil-metal structure, and specifically lining and surrounding rock, foundation and foundation, retaining wall and backfill, anchor and stratum, etc. Due to the difference in mechanical properties of materials on both sides of the contact interface, there are nonlinear, large deformation and local displacement discontinuity phenomena at the contact interface, and the stress and deformation conditions are relatively complex. For example, the safety of underground structures such as tunnels, basements and pile foundations in geotechnical engineering is closely related to their structural stress state, and the stress state of the structure mainly depends on the stress transfer mechanism of the contact interface between the structure and the stratum. Due to the differences in construction technology, surrounding environment and functional form, there are many types of contact interfaces with different roughness, load modes and surface shapes in underground concrete structures. At present, there are few studies in this field by domestic and foreign scholars, so it is of great theoretical and practical significance to carry out research on the mechanical properties of contact surfaces.

[0003] At present, conventional contact surface shear testers can only analyze the physical and mechanical parameters of the sample, but cannot visualize the microstructural characteristics of rock and soil during the shearing process, such as particle movement and extrusion crushing. Some scholars use numerical simulation methods to fit the particle displacement, stress and other information of clay, but it is not universal and is different from actual engineering. Through a simple modification of the indoor geotechnical direct shear instrument, preliminary visualization observations are carried out. There are still many problems such as a single observation angle, low matching between the image processing system and the instrument, a lack of innovation in the research methods of the mechanical behavior of the contact surface, and an increase in the error range after the instrument modification. Therefore, the existing visualization geotechnical direct shear instrument is not enough to completely solve these problems.

[0004] For many coastal cities, their underground infrastructure has been built for a certain number of years. Many subway tunnels, building foundations and underground frame chambers have suffered from diseases to varying degrees. This is partly due to the periodic changes in groundwater levels caused by the seawater tidal effect, and the fluctuations in the bedrock fissure water level, which in turn continuously erodes and scours the strata and structures, causing deformation and damage to underground structures. Therefore, it is of great significance to consider the impact of seepage on the interface between soil and structure.

[0005] Therefore, it is a technical problem that technical personnel in this field urgently need to solve to develop a large-scale contact surface shearing device that takes into account the seepage effect when shear occurs between the structure and different materials and collects the micromechanical information of the contact surface during the whole process. Summary of the invention

[0006] The purpose of the present invention is to propose a visual contact surface direct shear apparatus that takes into account the coupling effect of seepage and structure, has the test capability of independently applying normal static loads, dynamic loads and tangential static loads, can simulate the seepage effect of groundwater during the shearing process of the sample, and has the function of macroscopic and microscopic observation of the mechanical properties of the contact surface, and can carry out direct shear tests of equal-section and variable-section surfaces.

[0007] A visual contact surface direct shear instrument considering the coupling effect of seepage and structure, comprising a main frame, a normal force application system, a shear force application system, an electrical integrated circuit box, a shear box system, a seepage control system, an image acquisition system, an information monitoring and acquisition system and a slide system; the shear box system is arranged on the slide system, the slide system is fixed to the inner bottom of the main frame, the normal force application system and the electrical integrated circuit box are arranged on the upper part of the main frame, the shear force application system is arranged on the lower right part of the main frame, the seepage control system is arranged on the upper right part of the main frame, and the image acquisition system is arranged on the front of the main frame. The shooting direction is facing the shear box system; the shear box system is used to place the sample and perform direct shear test on the contact surface of the sample; the normal force application system is used to apply vertical static and dynamic force to the sample; the shear force application system is used to apply horizontal shear force to the sample; the seepage control system is used to regulate the seepage of the sample; the image acquisition system is used to capture images of the cross section of the sample contact surface during the shearing process; the information monitoring and acquisition system is used to collect load, displacement, water content, pore water pressure and permeability data of the sample; the slide system is used to provide horizontal displacement power for the shear box system when shearing the sample.

[0008] The above-mentioned visualized contact surface direct shear instrument that considers the coupling effect of seepage and structure, wherein the shear box system includes an upper shear box, a lower shear box, a connecting box, a shear box horizontal fixer, a rigid pressure plate, and a sealing plate; the top of the upper shear box fits with the bottom of the connecting box and is connected by a pin; the rigid pressure plate, the sealing plate, and the water storage tray are placed in the connecting box from top to bottom in sequence; the upper shear box is connected to the lower shear box through a shear box horizontal fixer, and the shear box horizontal fixer is composed of a guide seat and a horizontal pulley; the lower shear box is connected to the mud and water temporary storage tray by a pin; the mud and water temporary storage tray is fixed on a rigid base.

[0009] The above-mentioned visualized contact surface direct shear apparatus that takes into account the coupling effect of seepage and structure, wherein the right side of the front side of the lower shear box is provided with a shear area adjustment plate that can change the size of the shear interface and a telescopic pressure rod that controls the position of the adjustment plate, as well as a left top force transmission pad that transmits shear force, and a permeable plate that discharges the seepage water flow.

[0010] The above-mentioned visualized contact surface direct shear apparatus considering the coupling effect of seepage and structure, wherein the normal force application system includes a vertical servo actuator, a hydraulic pump, a cylinder, a measurement controller, and a computer control software; the vertical servo actuator is composed of a lower head and a servo motor, and applies a normal force to the sample through a rigid pressure plate; the measurement controller connects the vertical servo actuator and the hydraulic pump; the hydraulic pump connects the cylinder and the measurement controller; the measurement controller is connected to the computer through a data cable via an electrical integrated circuit box, and the closed-loop control of the normal loading pressure, displacement, and frequency, as well as the data reception of the load sensor and the displacement sensor, is realized through the computer control software.

[0011] The above-mentioned visualized contact surface direct shear apparatus considering the coupling effect of seepage and structure, wherein the shear force application system includes a horizontal servo actuator, a hydraulic pump, a cylinder, a measurement controller, and computer control software; the horizontal servo actuator is composed of a left top head and a servo motor, and applies a tangential force to the sample through the left top head force transmission pad; the measurement controller connects the horizontal servo actuator and the hydraulic pump; the hydraulic pump connects the cylinder and the measurement controller; the measurement controller is connected to the computer through a data cable via an electrical integrated circuit box, and the closed-loop control of the shear force and shear rate, as well as the data reception of the load sensor and the displacement sensor, is realized through the computer software.

[0012] The above-mentioned visualized contact surface direct shear apparatus considering the coupling effect of seepage and structure, wherein the seepage control system includes a constant temperature water tank, a water inlet pipe, a water inlet hole, a pressure water pump, a water inlet control valve, a water storage tray, a drain valve, a drain trough, a drain pipe, an exhaust hole, a permeable plate, a seepage control device, a mud and water temporary storage tray, and a mud and water recovery tank; the constant temperature water tank is connected to the seepage control device through the water inlet pipe via the water inlet control valve; the seepage control device is connected to the water storage tray through the water inlet pipe via the water inlet hole; the pressure water pump is connected to the constant temperature water tank, responsible for pumping water to the water inlet pipe; the permeable plate is placed at the bottom of the inner side of the lower shear box; the drain trough is arranged at the bottom of the inner side of the lower shear box; the drain trough is connected to the drain pipe; the drain pipe extends to the mud and water temporary storage tray; the mud and water temporary storage tray is connected to the mud and water recovery tank through the drain pipe.

[0013] The above-mentioned visualized contact surface direct shear instrument considering the coupling effect of seepage and structure, wherein the image acquisition system includes a CDD high-speed camera, an Edmund telecentric long-distance lens, a camera mechanical arm, an image transmission data cable, and a computer image processing software; the Edmund telecentric long-distance lens and the image transmission data cable are installed on the CDD high-speed camera; the CDD high-speed camera is installed at the head end of the forearm of the camera mechanical arm and is connected to the computer through the image transmission data cable; the tail end of the large arm of the camera mechanical arm is fixed to the upper front part of the main frame.

[0014] The above-mentioned visualized contact surface direct shear instrument that considers the coupling effect of seepage and structure, wherein the information monitoring and collection system includes a vertical load sensor, a horizontal load sensor, a vertical displacement sensor, a horizontal displacement sensor, a moisture sensor, a flow meter, an osmometer, and a data transmission interface; the load sensor and the displacement sensor transmit the monitoring data to the computer through the measurement controller; the moisture sensor and the osmometer are arranged on the inner wall of the shear box and transmitted to the computer through the data transmission interface; the flow meter is installed on the water inlet pipe close to the seepage control device, and the monitoring data is read through the monitoring display screen.

[0015] The above-mentioned visualized contact surface direct shear apparatus considering the coupling effect of seepage and structure, wherein the slide system includes a rigid base, an X-direction guide rail, an X-direction slide, a Y-direction guide rail, and a Y-direction slide; the mud and water temporary storage tray is fixed on the rigid base; the X-direction slide is installed at the bottom of the rigid base; the X-direction slide slides on the X-direction guide rail; the Y-direction slide is installed at the bottom of the Y-direction guide rail; and the Y-direction slide slides on the Y-direction guide rail.

[0016] The visual contact surface direct shear instrument considering the coupling effect of seepage and structure proposed in the present invention has the following beneficial effects:

[0017] 1. The shear box system of the present invention has the ability to conduct direct shear tests with equal and variable sections by setting a lower shear box with a variable shear area; through the visual transformation of the shear box, macro and micro observations of the shear characteristics of the soil-structure contact surface under seepage and complex load conditions are realized; by setting a larger shear area, the influence of boundary effects on the shear strength determination of the specimen is effectively reduced, thereby improving the accuracy of the test results.

[0018] 2. The normal force application system of the present invention realizes the precise application of normal static and dynamic load size and frequency through hydraulic servo control, and has the test function of simulating complex extreme load conditions; the device is easy to operate, the system runs safely and stably, and can fully restore the dynamic characteristics of the sample contact interface.

[0019] 3. The seepage control system of the present invention realizes a high degree of simulation of groundwater seepage, and achieves seepage regulation of the sample during the shear process through the seepage control device, so as to provide more realistic soil mechanical behavior, which is closer to actual engineering conditions.

[0020] 4. The image acquisition system of the present invention uses a high-definition camera to shoot the entire process of the shear contact interface, and then uses computer digital image processing software to process the image to obtain microscopic dynamic information on the displacement of soil particles and the form of crushing and crack extension at the contact surface between soil and structure during the test.

[0021] 5. The present invention realizes the seepage effect when shear occurs on the contact surface between soil and structure. The visual shear box combined with the high-speed camera realizes the observation of the mechanical properties of the contact surface from a microscopic level, and the special normal loading device has the test capability of simulating complex dynamic loads, providing experimental conditions for the study of the mechanical properties of the contact surface of water-soil-structure coupling under storm surge load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 It is a front structural schematic diagram of a visual contact surface direct shear instrument considering the seepage and structural coupling effect according to an embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of the back structure of a visual contact surface direct shear instrument considering the seepage and structural coupling effect according to an embodiment of the present invention;

[0025] Figure 3 It is a structural schematic diagram of an upper shear box and a lower shear box;

[0026] Figure 4 It is a side structural schematic diagram of a visualized contact surface direct shear instrument taking into account the seepage and structural coupling effect according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings. Several embodiments of the present invention are shown in the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0028] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right", "upper", "lower" and similar expressions used herein are for illustrative purposes only and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] See also Figures 1 to 4 The embodiment of the present invention proposes a visual contact surface direct shear instrument that takes into account the coupling effect of seepage and structure, including a main frame 1, a normal force application system 2, a shear force application system 3, an electrical integrated circuit box 4, a shear box system 5, a seepage control system 6, an image acquisition system 7, an information monitoring and acquisition system 8, and a slide system 9.

[0031] The shear box system 5 is used to place the sample and conduct direct shear test on the contact surface of the sample; the normal force application system 2 applies vertical static and dynamic force to the sample; the shear force application system 3 applies horizontal shear force to the sample; the seepage control system 6 regulates the seepage of the sample; the image acquisition system 7 acquires images of the cross section of the sample contact surface during the shearing process; the information monitoring and acquisition system 8 acquires the load, displacement, water content, pore water pressure, and permeability data of the sample. The slide system 9 provides horizontal displacement power for the shear box system 5 when the sample is sheared.

[0032] Specifically, the shear box system 5 includes an upper shear box 20, a lower shear box 21, a connecting box 29, a shear box horizontal fixer 25, a rigid pressure plate 18, and a sealing plate 19; the top of the upper shear box 20 is fitted with the bottom of the connecting box 29 and connected by a latch; the rigid pressure plate 18, the sealing plate 19, and the water storage tray 33 are placed in the connecting box 29 from top to bottom; the upper shear box 20 is connected to the lower shear box 21 through the shear box horizontal fixer 25, and the shear box horizontal fixer 25 is composed of a guide seat and a horizontal pulley; the lower shear box 21 is connected to the mud and water temporary storage tray 39 through a latch; the mud and water temporary storage tray 39 is fixed on the rigid base 53.

[0033] In this embodiment, the front side panels of the upper shear box 20 and the lower shear box 21 in the shear box system 5 are both made of fully vacuum tempered glass, and the rest are made of steel; the internal dimensions of the upper shear box 20 are 500mm×500mm×150mm; the internal dimensions of the lower shear box 21 are 800mm×500mm×150mm; the right side of the front side of the lower shear box 21 is provided with a shear area adjustment plate 22 that can change the size of the shear interface and a telescopic pressure rod 23 that controls the position of the adjustment plate, as well as a left top force transmission pad 24 that transmits shear force, and a permeable plate 38 for discharging the infiltrated water flow is also provided at the inner bottom. The adjustment plate 22 controls the movement and fixed position through the telescopic pressure rod 23; the connecting box 29 fixes the rigid pressure plate 18, the sealing plate 19 and the water storage tray 33 on the same vertical line; the rigid pressure plate 18 is made of a metal matrix composite material, which can evenly transfer the normal force downward to the contact surface of the sample; the sealing plate 19 is provided with sealing rubber strips around it, which can effectively prevent the infiltrated water from escaping from the top; the inner wall of the shear box is arranged with a moisture content sensor 49 and a monitoring circuit board of the piezometer 51; the shear box horizontal fixer 25 is composed of a guide seat and a horizontal pulley, wherein the guide seat is installed at the rear of the lower shear box 21, and the horizontal pulley is installed at the rear of the upper shear box 20, which can ensure that the sample is always in horizontal shear during the direct shear test.

[0034] The normal force application system 2 includes a vertical servo actuator 10, a hydraulic pump 11, a cylinder 12, a measurement controller 13, and computer control software; the vertical servo actuator 10 is composed of a lower ejector head and a servo motor, and applies a normal force to the sample through a rigid pressure plate 18; the measurement controller 13 connects the vertical servo actuator 10 and the hydraulic pump 11; the hydraulic pump 11 connects the cylinder 12 and the measurement controller 13; the measurement controller 13 is connected to the computer through a data cable via the electrical integrated circuit box 4, and the closed-loop control of the normal loading pressure, displacement, and frequency, as well as the data reception of the load sensor and the displacement sensor, is realized through the computer control software.

[0035] In this embodiment, the vertical servo actuator 10 can realize single loading and cyclic loading of the normal force. The maximum force value in the vertical direction is 800kN (80 tons), the maximum axial stroke is ±180mm, the maximum dynamic load application frequency is 8Hz, the amplitude is 2mm, and the displacement measurement accuracy is 0.1%FS; a vertical load sensor 45 is provided at the end of the lower head, and a plurality of load sensors with different ranges are provided to adapt to tests with different normal forces and different load frequency requirements to ensure the measurement accuracy of the normal force; a vertical displacement sensor 47 is arranged at the inner top of the main frame 1, and is used to measure the normal compression of the sample under the action of the normal force.

[0036] The shear force applying system 3 includes a horizontal servo actuator 14, a hydraulic pump 15, a cylinder 16, a measuring controller 17, and computer control software; the horizontal servo actuator 14 is composed of a left top head and a servo motor, and applies a tangential force to the sample through the left top head force transmission pad 24; the measuring controller 17 connects the horizontal servo actuator 14 and the hydraulic pump 15; the hydraulic pump 15 connects the cylinder 16 and the measuring controller 17; the measuring controller 17 is connected to the computer through a data cable via the electrical integrated circuit box 4, and realizes closed-loop control of shear force and shear rate through computer software, as well as data reception of load sensors and displacement sensors.

[0037] In this embodiment, the horizontal servo actuator 14 realizes the shear displacement of the sample contact surface by applying horizontal force to the left top force transmission pad 24 of the lower shear box 21. The maximum force value in the horizontal direction is 500kN (50 tons), the shear rate range is 0.00025-5mm / min, and the maximum horizontal stroke is ±150mm; the horizontal load sensor 46 is arranged on the left part of the main frame 1, and a plurality of load sensors with different ranges are provided to adapt to tests with different shear force and shear rate requirements and improve the measurement accuracy of the shear force; the horizontal displacement sensor 48 is arranged at the lower part of the horizontal servo actuator 14, and is used to measure the horizontal displacement of the sample under the action of the shear force.

[0038] The seepage control system 6 is intended to artificially control the seepage effect of simulated groundwater level changes on the soil, and includes a constant temperature water tank 26, a water inlet pipe 27, a water inlet hole 28, a pressure water pump 30, a water inlet control valve 31, a water storage tray 33, a drain valve 34, a drain trough 35, a drain pipe 36, an exhaust hole 37, a permeable plate 38, a seepage control device 32, a muddy water temporary storage tray 39, and a muddy water recovery tank 40; the constant temperature water tank 26 is connected to the seepage control device 32 through the water inlet pipe 27 via the water inlet control valve 31. Control device 32; seepage control device 32 is connected to water storage tray 33 through water inlet pipe 27 via water inlet hole 28; pressure water pump 30 is connected to constant temperature water tank 26, responsible for pumping water to water inlet pipe 27; water-permeable plate 38 is placed at the bottom of the inner side of lower shear box 21; drainage groove 35 is arranged at the bottom of the inner side of lower shear box 21; drainage groove 35 is connected to drainage pipe 36; drainage pipe 36 extends to mud and water temporary storage tray 39; mud and water temporary storage tray 39 is connected to mud and water recovery tank 40 via drainage pipe 36.

[0039] In this embodiment, the constant temperature water tank 26 is used to store clean water and adjust the water temperature according to the test requirements; the water inlet control valve 31 controls the opening and closing of the water flow; the seepage control device 32 controls the flow rate and flow velocity of the water; the bottom of the water storage tray 33 is provided with dense holes, which can evenly infiltrate the water flow into the sample; the drain valve 34 controls the opening and closing of the seeping mud and water; the exhaust hole 37 is provided with a pressure control valve, and when the pressure exceeds a certain set value, the valve switch is triggered to exhaust, so as to ensure the water flow and discharge the internal gas at the same time, so as to ensure the constant penetration pressure; there are 3 drainage grooves 35, and after the water flow penetrates the sample, it flows to the drainage groove 35 through the permeable plate 38, and then flows to the mud and water temporary storage tray 39 through the drainage pipe 36; after the test is completed, the mud and water are discharged from the mud and water temporary storage tray 39 to the mud and water recovery box 40; the mud and water recovery box 40 is equipped with an oven, which can dry the mud and water, separate the water and soil particles, and realize the recycling of the rock and soil particles of the sample.

[0040] The image acquisition system 7 is used to shoot the entire shearing process of the contact surface of the sample, observe the relative displacement, rotation and crushing state of the rock and soil particles in real time, and later combine with computer digital image processing software to further obtain the displacement field, strain field and velocity field of the rock and soil particles during the shearing process. It includes a CDD high-speed camera 41, an Edmund telecentric long-distance lens 42, a camera mechanical arm 43, an image transmission data cable 44, and a computer image processing software; the Edmund telecentric long-distance lens 42 and the image transmission data cable 44 are installed on the CDD high-speed camera 41; the CDD high-speed camera 41 is installed at the head end of the forearm of the camera mechanical arm 43, and is connected to the computer through the image transmission data cable 44; the tail end of the upper arm of the camera mechanical arm 43 is fixed to the upper front side of the main frame 1.

[0041] In this embodiment, the CCD high-speed camera 41 is an image acquisition device with a maximum frame rate of 79 frames / s, which is used to collect dynamic displacement images of soil particles; the Edmund telecentric long-distance lens 42 is used to correct the parallax of ordinary lenses and eliminate the influence of the height of the measured object on the results; the image is post-processed by coloring through computer image processing software to more intuitively obtain the displacement changes of any point in the image at each moment.

[0042] The information monitoring and collection system 8 includes a vertical load sensor 45, a horizontal load sensor 46, a vertical displacement sensor 47, a horizontal displacement sensor 48, a moisture sensor 49, a flow meter 50, a piezometer 51, and a data transmission interface 52; the load sensor and the displacement sensor transmit the monitoring data to the computer through the measurement controller; the moisture sensor 49 and the piezometer 51 are arranged on the inner wall of the shear box and are transmitted to the computer through the data transmission interface 52; the flow meter 50 is installed on the water inlet pipe 27 close to the seepage control device 32, and the monitoring data is read through the monitoring display screen.

[0043] In this embodiment, all load sensors are load sensors with multiple different ranges; all displacement sensors are laser displacement sensors with a measurement accuracy of 0.005mm; the moisture content sensor 49 is a resistive moisture sensor with an accuracy of ±0.1%; the flow meter 50 is an integrated electromagnetic flow meter with a measurement accuracy of ±0.2%; the osmometer 51 is a vibrating string osmometer, which can accurately measure the pore water pressure of the sample; the digital signal interface of the above sensors is converted into a USB interface through a converter, transmitted to the computer through a data cable via a data transmission interface 52, and the monitoring data is recorded and a curve chart is drawn through computer software.

[0044] The slide system 9 includes a rigid base 53, an X-direction guide rail 54, an X-direction slide 55, a Y-direction guide rail 56, and a Y-direction slide 57; the muddy water temporary storage tray 39 is fixed on the rigid base 53; the X-direction slide 55 is installed at the bottom of the rigid base 53; the X-direction slide 55 slides on the X-direction guide rail 54; the Y-direction slide 57 is installed at the bottom of the Y-direction guide rail 56; the Y-direction slide 57 slides on the Y-direction guide rail 56. The X-direction pulley is responsible for the X-direction movement of the sample during the test; the Y-direction pulley is responsible for the Y-direction movement of the shear box system during the test box loading and unloading. The slide system is made of high-density structural steel and can withstand 150 tons of pressure.

[0045] The conventional test operation steps of the visual contact surface direct shear instrument of this embodiment are as follows:

[0046] 1) Place the pre-prepared concrete test block in the lower box of the shear box;

[0047] 2) Place soil sample on the upper box of the shear box, and the soil sample is consolidated soil;

[0048] 3) Apply silicone waterproof glue around the contact surface of the sample. The glue has good elastic deformation ability and can effectively prevent the penetration water from seeping out from the gap between the upper and lower shear boxes during the shearing process;

[0049] 4) The connection box is placed on the top of the upper shear box, and the water storage tray, sealing plate and rigid pressure plate are placed in the connection box in sequence, and the upper and lower shear boxes are fixed to the connection box with latches;

[0050] 5) Set the normal force value, actuation frequency, amplitude and waveform (such as triangle wave, sine wave and square wave, etc.) through the computer;

[0051] 6) Setting the step-by-step tangential force value and displacement rate through the computer;

[0052] 7) The seepage control device sets a constant water flow seepage pressure;

[0053] 8) Adjust the camera angle to aim at the contact surface and prepare to shoot;

[0054] 9) Start various monitors through the computer to start recording data;

[0055] 10) Pull out the pin and start applying normal force to the target value;

[0056] 11) Begin to apply tangential force to shear the sample, and at the same time open the water inlet control valve to infiltrate the sample, and dynamically maintain the target infiltration pressure;

[0057] 12) The test ends when the sample is slowly sheared until the shear force reaches a peak and then decreases.

[0058] In summary, the visual contact surface direct shear instrument considering the coupling effect of seepage and structure proposed in the present invention has the following beneficial effects:

[0059] 1. The shear box system of the present invention has the ability to conduct direct shear tests with equal and variable sections by setting a lower shear box with a variable shear area; through the visual transformation of the shear box, macro and micro observations of the shear characteristics of the soil-structure contact surface under seepage and complex load conditions are realized; by setting a larger shear area, the influence of boundary effects on the shear strength determination of the specimen is effectively reduced, thereby improving the accuracy of the test results.

[0060] 2. The normal force application system of the present invention realizes the precise application of normal static and dynamic load size and frequency through hydraulic servo control, and has the test function of simulating complex extreme load conditions; the device is easy to operate, the system runs safely and stably, and can fully restore the dynamic characteristics of the sample contact interface.

[0061] 3. The seepage control system of the present invention realizes a high degree of simulation of groundwater seepage, and achieves seepage regulation of the sample during the shear process through the seepage control device, so as to provide more realistic soil mechanical behavior, which is closer to actual engineering conditions.

[0062] 4. The image acquisition system of the present invention uses a high-definition camera to shoot the entire process of the shear contact interface, and then uses computer digital image processing software to process the image to obtain microscopic dynamic information on the displacement of soil particles and the form of crushing and crack extension at the contact surface between soil and structure during the test.

[0063] 5. The present invention realizes the seepage effect when shear occurs on the contact surface between soil and structure. The visual shear box combined with the high-speed camera realizes the observation of the mechanical properties of the contact surface from a microscopic level, and the special normal loading device has the test capability of simulating complex dynamic loads, providing experimental conditions for the study of the mechanical properties of the contact surface of water-soil-structure coupling under storm surge load conditions.

[0064] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0065] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A visual contact surface direct shear instrument considering the coupling effect of seepage and structure, characterized in that: The invention comprises a main frame (1), a normal force applying system (2), a shear force applying system (3), an electrical integrated circuit box (4), a shear box system (5), a seepage control system (6), an image acquisition system (7), an information monitoring and acquisition system (8) and a slide system (9); the shear box system (5) is arranged on the slide system (9), the slide system (9) is fixed to the inner bottom of the main frame (1), the normal force applying system (2) and the electrical integrated circuit box (4) are arranged on the upper part of the main frame (1), the shear force applying system (3) is arranged on the lower right part of the main frame (1), the seepage control system (6) is arranged on the upper right part of the main frame (1), and the image acquisition system (7) is arranged on the upper right part of the main frame (1). The front part of the body frame (1) is photographed in a direction facing the shear box system (5); the shear box system (5) is used to place the sample and perform a direct shear test on the contact surface of the sample; the normal force application system (2) is used to apply vertical static and dynamic forces to the sample; the shear force application system (3) is used to apply horizontal shear force to the sample; the seepage control system (6) is used to control the seepage of the sample; the image acquisition system (7) is used to acquire images of the cross section of the contact surface of the sample during the shearing process; the information monitoring and acquisition system (8) is used to acquire load, displacement, water content, pore water pressure, and permeability data of the sample; and the slide system (9) is used to provide horizontal displacement power for the shear box system (5) when the sample is sheared.

2. The visual contact surface direct shear instrument considering the coupling effect of seepage and structure according to claim 1 is characterized in that: The shear box system (5) comprises an upper shear box (20), a lower shear box (21), a connecting box (29), a shear box horizontal fixer (25), a rigid pressure plate (18), and a sealing plate (19); the top of the upper shear box (20) fits with the bottom of the connecting box (29) and is connected by a latch; the rigid pressure plate (18), the sealing plate (19), and the water storage tray (33) are placed in the connecting box (29) from top to bottom; the upper shear box (20) is connected to the lower shear box (21) through the shear box horizontal fixer (25), and the shear box horizontal fixer (25) is composed of a guide seat and a horizontal pulley; the lower shear box (21) is connected to the mud and water temporary storage tray (39) by a latch; the mud and water temporary storage tray (39) is fixed on a rigid base (53).

3. The visual contact surface direct shear instrument considering the coupling effect of seepage and structure according to claim 2 is characterized in that: The right side of the front side of the lower shear box (21) is provided with a shear area adjustment plate (22) capable of changing the size of the shear interface, a telescopic pressure rod (23) for controlling the position of the adjustment plate, and a left top force transmission pad (24) for transmitting shear force, and a water permeable plate (38) for discharging the infiltrated water flow is also provided at the inner bottom.

4. The visual contact surface direct shear instrument considering the coupling effect of seepage and structure according to claim 1 is characterized in that: The normal force application system (2) comprises a vertical servo actuator (10), a hydraulic pump (11), an oil cylinder (12), a measurement controller (13), and computer control software; the vertical servo actuator (10) is composed of a lower ejector head and a servo motor, and applies a normal force to a sample through a rigid pressure plate (18); the measurement controller (13) is connected to the vertical servo actuator (10) and the hydraulic pump (11); the hydraulic pump (11) is connected to the oil cylinder (12) and the measurement controller (13); the measurement controller (13) is connected to a computer through a data line via an electrical integrated circuit box (4), and the closed-loop control of normal loading pressure, displacement, and frequency, as well as data reception of a load sensor and a displacement sensor, is realized through the computer control software.

5. The visual contact surface direct shear instrument considering the coupling effect of seepage and structure according to claim 1 is characterized in that: The shear force applying system (3) comprises a horizontal servo actuator (14), a hydraulic pump (15), an oil cylinder (16), a measuring controller (17), and computer control software; the horizontal servo actuator (14) is composed of a left top head and a servo motor, and applies a tangential force to the sample through a left top head force transmission pad (24); the measuring controller (17) is connected to the horizontal servo actuator (14) and the hydraulic pump (15); the hydraulic pump (15) is connected to the oil cylinder (16) and the measuring controller (17); the measuring controller (17) is connected to the computer through a data line via an electrical integrated circuit box (4), and the closed-loop control of the shear force and the shear rate, as well as the data reception of the load sensor and the displacement sensor, is realized through the computer software.

6. The visual contact surface direct shear instrument considering the coupling effect of seepage and structure according to claim 1 is characterized in that: The seepage control system (6) comprises a constant temperature water tank (26), a water inlet pipe (27), a water inlet hole (28), a pressure water pump (30), a water inlet control valve (31), a water storage tray (33), a drainage valve (34), a drainage trough (35), a drainage pipe (36), an air vent (37), a water permeable plate (38), a seepage control device (32), a muddy water temporary storage tray (39), and a muddy water recovery tank (40); the constant temperature water tank (26) is connected to the seepage control device (32) via the water inlet control valve (31) and the water inlet pipe (27); the seepage control device The housing (32) is connected to a water storage tray (33) through a water inlet hole (28) and a water inlet pipe (27); a pressure water pump (30) is connected to a constant temperature water tank (26) and is responsible for pumping water to the water inlet pipe (27); a water permeable plate (38) is arranged at the bottom of the inner side of the lower shear box (21); a drainage groove (35) is arranged at the bottom of the inner side of the lower shear box (21); the drainage groove (35) is connected to a drainage pipe (36); the drainage pipe (36) extends into a muddy water temporary storage tray (39); and the muddy water temporary storage tray (39) is connected to a muddy water recovery tank (40) through the drainage pipe (36).

7. The visual contact surface direct shear instrument considering the coupling effect of seepage and structure according to claim 1 is characterized in that: The image acquisition system (7) comprises a CDD high-speed camera (41), an Edmund telecentric long-distance lens (42), a camera mechanical arm (43), an image transmission data line (44), and computer image processing software; the Edmund telecentric long-distance lens (42) and the image transmission data line (44) are installed on the CDD high-speed camera (41); the CDD high-speed camera (41) is installed at the head end of the forearm of the camera mechanical arm (43) and is connected to the computer via the image transmission data line (44); the tail end of the upper arm of the camera mechanical arm (43) is fixed to the upper front part of the main frame (1).

8. The visual contact surface direct shear instrument considering the coupling effect of seepage and structure according to claim 1 is characterized in that: The information monitoring and collection system (8) comprises a vertical load sensor (45), a horizontal load sensor (46), a vertical displacement sensor (47), a horizontal displacement sensor (48), a moisture content sensor (49), a flow meter (50), an osmometer (51), and a data transmission interface (52); the load sensor and the displacement sensor transmit the monitoring data to a computer via a measurement controller; the moisture content sensor (49) and the osmometer (51) are arranged on the inner wall of the shear box, and the data are transmitted to the computer via the data transmission interface (52); the flow meter (50) is installed on the water inlet pipe (27) close to the seepage control device (32), and the monitoring data is read via a monitoring display screen.

9. The visual contact surface direct shear instrument considering the seepage and structure coupling effect according to claim 1 is characterized in that: The slide system (9) comprises a rigid base (53), an X-direction guide rail (54), an X-direction slide (55), a Y-direction guide rail (56), and a Y-direction slide (57); the mud and water temporary storage tray (39) is fixed on the rigid base (53); the X-direction slide (55) is installed at the bottom of the rigid base (53); the X-direction slide (55) slides on the X-direction guide rail (54); the Y-direction slide (57) is installed at the bottom of the Y-direction guide rail (56); and the Y-direction slide (57) slides on the Y-direction guide rail (56).

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