A shear test device capable of adjusting sample response stress

Abstract

The present application discloses a shear test device capable of regulating the response stress of a sample, and relates to the field of geotechnical engineering. The device comprises: a lower shear box, an upper shear box, a normal loading plate, a tangential loading head, a water pump, a pressure film, a plurality of film sensors and a host computer. After the host computer controls the normal loading plate to apply a constant downward pressure to the soil sample to be tested, the water pump is controlled to inject or pump water into the pressure film according to the response stress of the soil sample to be tested at different positions on the surface of the pressure film, so as to regulate the response stress of the soil sample to be tested at different positions on the surface of the pressure film, and after the response stress reaches the target value, the tangential loading head is controlled to move the lower shear box, so that the lower shear box and the upper shear box can achieve shearing. The present application accurately regulates the response stress of the soil sample to be tested at different positions.

Description

Technical Field

[0001] The present application relates to the field of geotechnical engineering, and in particular to a shear test device capable of adjusting the response stress of a sample. Background Art

[0002] The mechanical and deformation properties of the soil-structure interface are key factors that determine the interaction between soil and structure. They bear the important functions of load transfer and deformation coordination between soil and structure, and are often the weak link in the system. The shear sliding displacement, stress state and other stress-deformation properties of the thin soil at the interface are quite different from those of the rest of the soil. It is crucial to clarify the stress-deformation characteristics of the soil-structure interface and the form of shear failure. At present, there is no comprehensive guidance on the stress-deformation parameters of the soil-structure interface in the relevant standards, and the understanding of the shear properties of the soil-structure interface is still unclear. Due to the insufficient performance of the test equipment and the imperfect boundary condition control technology, the stress-deformation characteristics of the soil-structure interface obtained through various shear tests are often low in universality, poor in parameter reliability, and unclear in the stress-strain state of the specimen, making it difficult to characterize the actual working conditions.

[0003] Boundary conditions are crucial to the shear mechanical behavior of interfaces, especially the stability of boundary conditions during the shear process. The reasonable and reliable regular parameters provided by the test results of accurate and stable boundary conditions during the shear process are the basis of theoretical analysis, numerical simulation, and engineering design. Constant normal pressure is the most common boundary condition of existing instruments. In related technologies, the normal constant pressure is often provided by the loading head, and the point load is converted into a uniformly distributed load on the specimen through a rigid loading plate connected to the loading head. However, after setting the normal pressure, the relevant instruments only rely on the control system to apply the load, without monitoring the actual stress response acting on the specimen, and there is no way to accurately control it. The accuracy and stability of the constant normal pressure environment need to be improved. Summary of the invention

[0004] The purpose of the present application is to provide a shear test device capable of adjusting the response stress of a sample, which can accurately adjust the response stress of a soil sample to be tested at different positions through a water pump and a pressure film.

[0005] To achieve the above objectives, this application provides the following solutions.

[0006] A shear test device capable of adjusting the response stress of a sample, wherein the sample is a soil sample to be tested, and the shear test device capable of adjusting the response stress of the sample comprises:

[0007] Lower shear box for placement of structural material.

[0008] The upper shear box is arranged above the lower shear box and is used for placing the soil sample to be tested.

[0009] The normal loading plate is used to apply a constant downward pressure to the soil sample to be tested.

[0010] A tangential loading head is used to move the lower shear box.

[0011] The pressure film is arranged on the inner wall of the upper shear box.

[0012] A water pump is connected to the pressure film and is used for injecting water into or pumping water out of the pressure film.

[0013] A plurality of film sensors are respectively located at different positions on the surface of the pressure film and inside the soil sample to be tested, and are used to detect the response stresses exerted on the soil sample to be tested at different positions on the surface of the pressure film.

[0014] The upper computer is connected to the film sensor, the water pump, the normal loading plate and the tangential loading head, and is used to control the normal loading plate to apply a constant downward pressure to the soil sample to be tested, and then control the water pump to inject or pump water into the pressure film according to the response stress of the soil sample to be tested at different positions on the surface of the pressure film, so as to regulate the response stress of the soil sample to be tested at different positions on the surface of the pressure film, and after the response stress reaches the target value, control the tangential loading head to move the lower shear box to achieve shearing between the lower shear box and the upper shear box.

[0015] According to the specific embodiments provided in this application, this application has the following technical effects:

[0016] The present application provides a shear test device with adjustable sample response stress. After a constant downward pressure is applied to a soil sample to be tested through a normal loading plate, the response stresses received by the soil sample to be tested at different positions on the surface of the pressure film are detected according to film sensors placed on the surface of the pressure film and inside the soil sample to be tested. According to the response stresses received by the soil sample to be tested at different positions on the surface of the pressure film, water is injected or pumped into the pressure film through a water pump to accurately adjust the response stresses received by the soil sample to be tested at different positions, so that the response stresses received by the soil sample to be tested at different positions all reach target values. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic structural diagram of a shear test device capable of adjusting the response stress of a sample provided in one embodiment of the present application.

[0019] Figure 2 This is a top view of section A in the structural schematic diagram of a shear test device capable of adjusting the response stress of a sample provided in one embodiment of the present application.

[0020] Reference numerals:

[0021] Upper shear box—1, lower shear box—2, soil sample to be tested—3, structural material—4, normal loading plate—5, tangential loading head—6, pressure film—7, film sensor—8, capillary—9, water pump—10, host computer—11, camera—12. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] In order to make the purpose, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0024] The present application also provides a shear test device capable of adjusting the response stress of a sample, wherein the sample is a soil sample 3 to be tested. Figure 1 and Figure 2 As shown, the shear test device capable of adjusting the sample response stress comprises:

[0025] The lower shear box 2 is used to place the structural material 4.

[0026] The upper shear box 1 is arranged above the lower shear box 2 and is used for placing the soil sample 3 to be tested.

[0027] The normal loading plate 5 is used to apply a constant downward pressure to the soil sample 3. Specifically, the normal loading plate 5 can be controlled to apply a constant pressure or a constant displacement.

[0028] The tangential loading head 6 is used to move the lower shear box 2.

[0029] The pressure film 7 is arranged on the inner wall of the upper shear box 1 .

[0030] The water pump 10 is connected to the pressure film 7 and is used for injecting water into or pumping water out of the pressure film 7 .

[0031] A plurality of film sensors 8 are respectively located at different positions on the surface of the pressure film 7 and inside the soil sample 3 to be tested, and are used to detect the response stresses exerted on the soil sample 3 to be tested at different positions on the surface of the pressure film 7 .

[0032] The host computer 11 is connected to the film sensor 8, the water pump 10, the normal loading plate 5 and the tangential loading head 6, and is used to control the normal loading plate 5 to apply a downward constant pressure to the soil sample 3 to be tested, and then, according to the response stress of the soil sample 3 to be tested at different positions on the surface of the pressure film 7, control the water pump 10 to inject or pump water into the pressure film 7 to adjust the response stress of the soil sample 3 to be tested at different positions on the surface of the pressure film 7, and after the response stress reaches the target value, control the tangential loading head 6 to move the lower shear box 2 so that the lower shear box 2 and the upper shear box 1 can achieve shearing. Specifically, the host computer 11 includes a proportional-integral-derivative (PID) controller, which receives the response stress measurement value of the film sensor 8, and adjusts the injection / pumping amount of the high-precision water pump 10 accordingly, so as to control the boundary response stress value of the soil sample, so that the soil sample to be tested is subjected to balanced stress at different positions.

[0033] As an optional implementation, the upper surface area of ​​the structural material 4 in the lower shear box 2 is larger than the lower surface area of ​​the soil sample 3 to be tested in the upper shear box 1, so as to control the shear surface size to remain unchanged during the shearing process.

[0034] As an optional embodiment, the shear test device with adjustable sample response stress also includes: a capillary 9, connected to the water pump 10 and the pressure film 7, and used to transfer the water in the water pump 10 to the pressure film 7 when filling water; and transfer the water in the pressure film 7 to the water pump 10 when pumping water.

[0035] As an optional implementation, the film sensor 8 is located at the interface between the capillary tube 9 and the pressure film 7. The capillary tube 9 and the film sensor 8 are installed at the same position to accurately control the response stress.

[0036] As an optional implementation, the normal loading plate 5 has the same shape as the soil sample 3 to be tested.

[0037] As an optional implementation, the pressure film 7 is flatly fixed to the inner wall of the upper shear box 1. Specifically, the pressure film 7 is flatly fixed to the inner wall of the upper shear box 1, and has a smooth surface.

[0038] As an optional implementation, the upper shear box 1 is round or square.

[0039] As an optional implementation, when the upper shear box 1 is square, the material of the upper shear box 1 is a rigid transparent material.

[0040] As an optional embodiment, the shear test device with adjustable sample response stress further includes: a camera 12. The camera 12 is connected to the host computer 11, and is used to collect an image of the soil sample 3 to be tested in the upper shear box 1 when the material of the upper shear box 1 is a rigid transparent material, so as to observe the deformation of the soil sample 3 to be tested in the upper shear box 1.

[0041] When the upper shear box 1 is cylindrical, the stress concentration phenomenon is small. When it is square, the soil deformation during the shearing process can be observed by using transparent materials or setting a transparent observation window in conjunction with a high-precision camera system.

[0042] As an optional implementation, the film sensors 8 are located at four corners in the upper shear box 1. The film sensors 8 are arranged at locations where stress concentration is likely to occur, such as corners of soil samples.

[0043] The present application uses a PID controller and a high-precision water pump 10 to real-time regulate the response stress value of the soil sample 3 to be tested detected by the thin film sensor 8 at each position, so that the force of the soil sample 3 to be tested at each position is balanced, avoiding the influence of local stress concentration on the shear test results, thereby creating a constant stress boundary condition that conforms to the actual situation for the sample, so as to improve the accuracy of the shear test results.

[0044] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0045] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A shear test device capable of adjusting the response stress of a sample, wherein the sample is a soil sample to be tested, characterized in that: The shear test device capable of adjusting the sample response stress comprises: a lower shear box for placing structural materials; An upper shear box is arranged above the lower shear box and is used to place the soil sample to be tested; the upper surface area of ​​the structural material in the lower shear box is larger than the lower surface area of ​​the soil sample to be tested in the upper shear box; A normal loading plate, used for applying a constant downward pressure to the soil sample to be tested; a tangential loading head for moving the lower shear box; A pressure film, arranged on the inner wall of the upper shear box; A water pump connected to the pressure film and used to inject or pump water into the pressure film; A plurality of thin film sensors are respectively located at different positions on the surface of the pressure film and inside the soil sample to be tested, and are used to detect the response stress of the soil sample to be tested at different positions on the surface of the pressure film; the plurality of thin film sensors are respectively located at four corners in the upper shear box; A capillary tube is connected to the water pump and the pressure film, and is used to transfer water in the water pump to the pressure film when filling water; and to transfer water in the pressure film to the water pump when pumping water; the film sensor is located at the interface between the capillary tube and the pressure film; The upper computer is connected to the film sensor, the water pump, the normal loading plate and the tangential loading head, and is used to control the normal loading plate to apply a constant downward pressure to the soil sample to be tested, and then control the water pump to inject or pump water into the pressure film according to the response stress of the soil sample to be tested at different positions on the surface of the pressure film, so as to regulate the response stress of the soil sample to be tested at different positions on the surface of the pressure film, and after the response stress reaches the target value, control the tangential loading head to move the lower shear box to achieve shearing between the lower shear box and the upper shear box.

2. The shear test device capable of adjusting the sample response stress according to claim 1, characterized in that: The normal loading plate has the same shape as the soil sample to be tested.

3. The shear test device capable of adjusting the sample response stress according to claim 1, characterized in that: The pressure film is flatly fixed on the inner wall of the upper shear box.

4. The shear test device capable of adjusting the sample response stress according to claim 1, characterized in that: The upper shear box is circular or square.

5. The shear test device capable of adjusting the sample response stress according to claim 4, characterized in that: When the upper shear box is square, the material of the upper shear box is a rigid transparent material.

6. The shear test device capable of adjusting the sample response stress according to claim 5, characterized in that: The shear test device capable of adjusting the sample response stress further comprises: The camera is connected to the host computer and is used to collect images of the soil sample to be tested in the upper shear box when the material of the upper shear box is a rigid transparent material, so as to observe the deformation of the soil sample to be tested in the upper shear box.

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