A true triaxial confining pressure seepage test chamber

Abstract

This utility model discloses a true triaxial confining pressure seepage test chamber, belonging to the technical field of geotechnical engineering testing equipment. The test chamber body includes a base, a confining pressure chamber fixedly connected above the base, a sample placed in the confining pressure chamber, an upper loading seepage shaft slidably connected to the top of the confining pressure chamber, and a seepage pressure plate fixedly connected to the lower end of the upper loading seepage shaft. A seepage channel is formed inside the upper loading seepage shaft. The test chamber body also includes two lateral loading shafts and lateral loading balance chambers corresponding to the lateral loading shafts. By integrating three independent loading shafts and seepage channels into one unit, this utility model solves the problems of existing technologies, such as difficulty in simulating the coupling effect of real three-dimensional stress and multi-directional seepage, complex structure, and single function. The lateral loading balance chambers ensure the stability of the loading, achieving a compact structure, high functional integration, and accurate testing.

Description

Technical Field

[0001] This utility model relates to the field of geotechnical engineering testing equipment, and in particular to a true triaxial confining pressure seepage test box. Background Technology

[0002] In deep geotechnical engineering, water conservancy and hydropower, and mining and oil and gas resource extraction, soil and rock masses are typically situated in complex environments of high stress and high fluid pressure. To accurately assess the stability and safety of engineering projects, precise laboratory tests must be conducted to examine the mechanical behavior and permeability characteristics of soil and rock masses under these complex conditions. Studies have shown that the geostress experienced by soil and rock masses deep underground is not usually equal in all directions, but rather exhibits a state where the magnitudes of the three principal stress directions are generally unequal, i.e., a "true triaxial" stress state.

[0003] Existing conventional triaxial testing equipment, while capable of applying axial and radial pressures, applies radial pressures that are equal in both horizontal directions and cannot be independently adjusted. This significantly differs from the actual non-isotropic stress conditions of soil and rock masses in nature. This simplification in stress simulation makes it difficult for test results to fully reflect the true deformation and failure patterns of soil and rock masses under in-situ stress paths, thus affecting the accuracy of engineering designs.

[0004] To address these issues, true triaxial testing equipment capable of applying independent principal stresses in three directions has emerged. However, conducting stress-flow coupling tests on these devices presents new structural challenges. The introduction of flow systems, such as high-pressure pipelines and fluid injection and discharge devices, often spatially interferes with the already complex true triaxial loading system. Existing solutions typically combine the loading system and flow system as two relatively independent modules, resulting in a bulky overall structure, low system integration, complex assembly operations, and the potential for errors due to the interaction between the loading axis and the flow path. This makes it difficult to achieve compact, efficient, and accurate true triaxial stress-flow coupling testing.

[0005] Therefore, this invention proposes a true triaxial confining pressure seepage test chamber to address the shortcomings of existing technologies. Utility Model Content

[0006] To overcome the above shortcomings, this utility model provides a true triaxial confining pressure seepage test chamber, which aims to improve the existing rock and soil seepage test devices, which are difficult to accurately simulate the real three-dimensional stress state of rock and soil while testing their multi-directional, high-pressure seepage characteristics.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a true triaxial confining pressure seepage test chamber, comprising: a base; a confining pressure chamber fixedly connected to the top of the base, wherein the top and side walls of the confining pressure chamber are respectively provided with loading shaft through holes, a sample is placed at the center of the confining pressure chamber, an upper loading seepage shaft is slidably connected to the loading shaft through hole at the top of the confining pressure chamber, and the upper loading seepage shaft has a seepage channel extending axially through its interior; and a seepage pressure plate, the seepage pressure plate being fixedly connected to the upper loading shaft. The lower end of the seepage shaft is used to abut against the top surface of the sample. The true triaxial confining pressure seepage test box also includes two lateral loading shafts. The two lateral loading shafts are slidably connected to the loading shaft through holes on the side wall of the confining pressure chamber, and the axes of the two lateral loading shafts are orthogonal to each other and perpendicular to the axis of the upper loading seepage shaft. Furthermore, the true triaxial confining pressure seepage test box also includes a lateral loading balance chamber corresponding to each of the lateral loading shafts. The lateral loading balance chamber is fixedly connected to the end of the lateral loading shaft away from the sample.

[0008] Furthermore, the true triaxial confining pressure seepage test chamber also includes a test chamber body, in which the confining pressure chamber, the lateral loading shaft, and the lateral loading balance chamber are all housed within the test chamber body.

[0009] Furthermore, the confining pressure chamber is also provided with a confining pressure medium interface for connecting to an external confining pressure control system.

[0010] Furthermore, the walls of the confining chamber are also provided with sensing interfaces for installing sensors.

[0011] Furthermore, the base is provided with a seepage pipe, one end of which is connected to the bottom of the sample.

[0012] Furthermore, the seepage channel within the upper loading seepage shaft is connected to the top of the sample via the seepage pressure plate, and the seepage pipe on the base is connected to the bottom of the sample, thereby forming a structure for realizing normal seepage.

[0013] Furthermore, a seepage channel is provided inside the lateral loading shaft.

[0014] Furthermore, the seepage channel within the lateral loading shaft is connected to the side of the sample to achieve horizontal seepage.

[0015] This utility model has the following beneficial effects: 1. This invention solves the problem of existing technologies' inability to simultaneously simulate real three-dimensional stress states and multi-directional seepage coupling effects in the same device by setting mutually perpendicular and independently loaded upper loading seepage shafts and two lateral loading shafts, and cleverly integrating seepage channels within these loading shafts. This design not only accurately reproduces the complex non-isotropic stress environment of underground soil and rock masses, but also allows for vertical or horizontal seepage testing during loading, thereby greatly enhancing functional integration, making the device structure more compact, and enabling a more comprehensive and realistic evaluation of the mechanical seepage coupling characteristics of materials.

[0016] 2. This invention solves the problems of data distortion caused by pressure fluctuations and the difficulty of sensor deployment under high pressure by equipping the lateral loading shaft with a lateral loading balance chamber and directly opening a dedicated sensing interface on the confining pressure chamber. The lateral loading balance chamber can actively compensate for pressure changes, ensuring the constantness and stability of loading conditions; while the integrated sensing interface provides a pathway for convenient installation and signal acquisition of various sensors such as stress, strain, and flow. The synergistic effect of these two features significantly improves the accuracy and controllability of the experimental process and the comprehensiveness of data monitoring, providing a solid guarantee for obtaining high-precision, multi-parameter, and reliable experimental results. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural diagram of a true triaxial confining pressure seepage test chamber proposed in this utility model; Figure 2 This is a schematic diagram of the upper loading seepage axis section of a true triaxial confined pressure seepage test box proposed in this utility model; Figure 3 This is a schematic diagram of the sample section structure of a true triaxial confining pressure seepage test chamber proposed in this utility model.

[0018] Legend: 1. Upper loading seepage shaft; 2. Confining pressure chamber; 3. Sample; 4. Base; 5. Seepage pressure plate; 6. Lateral loading balance chamber; 7. Lateral loading shaft; 8. Test box body. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] Please refer to Figures 1 to 3This utility model provides a true triaxial confining pressure seepage test chamber, which aims to solve the problem that existing soil and rock seepage test devices are difficult to accurately simulate the real three-dimensional stress state of soil and rock while testing their seepage characteristics in multiple directions and under high pressure.

[0021] The overall structure of this true triaxial confining pressure seepage test chamber is based on the base 4, with the confining pressure chamber 2 fixedly connected above the base 4. The confining pressure chamber 2 is a closed high-pressure cavity made of high-strength alloy material, used to create a high-pressure environment inside. Loading shaft through holes are opened on the top and two opposite side walls of the confining pressure chamber 2. The sample 3, as the test object, is placed in the center of the confining pressure chamber 2. The entire loading and seepage system is finally assembled and protected by the test chamber body 8. The test chamber body 8 houses the confining pressure chamber 2 and the loading system described later inside the test chamber body 8, forming a compact integrated structure.

[0022] The core structure of the true triaxial loading and seepage mainly includes a vertical loading seepage section and a horizontal loading section. The vertical loading seepage section consists of an upper loading seepage shaft 1 and a seepage pressure plate 5. The body of the upper loading seepage shaft 1 forms a sealed sliding connection with the loading shaft through hole at the top of the confining pressure chamber 2, so that the upper loading seepage shaft 1 can move in the vertical direction to apply load to the sample 3. The upper loading seepage shaft 1 has a seepage channel that runs through it along its axial direction to transport high-pressure seepage liquid. The seepage pressure plate 5 is fixedly connected to the lower end of the upper loading seepage shaft 1 away from the external loading end and directly abuts against the top surface of the sample 3. This structure allows the seepage pressure plate 5 to uniformly distribute the liquid from the seepage channel inside the upper loading seepage shaft 1 to the surface of the sample 3 while transmitting axial pressure.

[0023] The horizontal loading section includes two lateral loading shafts 7 and lateral loading balance chambers 6 corresponding to the two lateral loading shafts 7. The two lateral loading shafts 7 are respectively connected to the loading shaft through holes on the side wall of the confining pressure chamber 2 in a sealed sliding connection. The axes of the two lateral loading shafts 7 are orthogonal to each other and perpendicular to the axis of the upper loading seepage shaft 1, thus forming a three-dimensional orthogonal loading system. The lateral loading balance chamber 6 is fixedly connected to the end of the lateral loading shaft 7 away from the sample 3. The lateral loading balance chamber 6 is filled with high-pressure oil to compensate for the volume change of the hydraulic system during loading, thereby maintaining a constant lateral loading pressure.

[0024] The confining pressure chamber 2 has a confining pressure medium interface on its wall for connecting to an external confining pressure control system. This interface allows high-pressure confining pressure medium to be injected into the cavity inside the confining pressure chamber 2, thereby applying precise and controllable isotropic or anisotropic confining pressure to the sample 3. The confining pressure chamber 2 also has a sensing interface on its wall for installing sensors. This sensing interface provides a mounting position for monitoring elements such as stress-strain sensors, acoustic emission probes, and pore pressure gauges, enabling real-time data acquisition of the mechanical response and internal permeability of the sample 3 during the test.

[0025] Meanwhile, in order to construct a complete seepage path, a seepage pipe is provided inside the base 4. One end of the seepage pipe is connected to the bottom of the sample 3, and the other end is connected to an external fluid control and measurement system. In conjunction with the structure described in the first part, the seepage channel inside the upper loading seepage shaft 1 is connected to the top of the sample 3 via the seepage pressure plate 5, and the seepage pipe on the base 4 is connected to the bottom of the sample 3. Together, they constitute a structure for realizing normal seepage. High-pressure liquid can flow through the sample 3 from top to bottom or from bottom to top within this structure. In addition, a seepage channel is also provided inside the lateral loading shaft 7. When a horizontal seepage test is required, fluid can be injected through the seepage channel of one lateral loading shaft 7, flow through the sample 3, and then flow out from the seepage channel of the other opposite lateral loading shaft 7, thereby realizing a horizontal seepage test.

[0026] For the external hydraulic control system that drives the upper loading seepage shaft 1 and the lateral loading shaft 7, the seepage system that provides and regulates the seepage pressure, and the signal system that collects and processes data, those skilled in the art can use various conventional methods such as existing servo hydraulic sources, high-pressure fluid pumps, and data acquisition cards. The specific internal structure of these external systems is well-known in the art and will not be described in detail here.

[0027] As a preferred integrated implementation, in order to integrate the loading system, confining pressure system and seepage system into a compact and protected whole, the true triaxial confining pressure and seepage test box also includes a test box body 8. As an overall assembly and protection assembly, the test box body 8 houses the internal core components such as the confining pressure chamber 2, the lateral loading shaft 7 and the lateral loading balance chamber 6 inside the test box body 8. The frame structure of the test box body 8 provides space for the attachment and layout of external hydraulic pipelines and data cables.

[0028] As a preferred embodiment for achieving precise environmental control and data monitoring, the confining pressure chamber 2 is also provided with an interface for connecting to an external control system. Specifically, the confining pressure chamber 2 is provided with a confining pressure medium interface, which adopts a high-pressure thread form and is used to make a sealed connection with the external confining pressure control system pipeline to inject or discharge the confining pressure medium. Based on the confining pressure medium interface, the confining pressure chamber 2 is further provided with a sensing interface, which is a standard connector port with a sealed feedthrough structure, used to lead the signal cables of various sensors installed on or inside the sample 3 out of the confining pressure chamber 2 and connect them to an external data acquisition system.

[0029] As a preferred embodiment for achieving normal permeation testing, a permeation pipe is provided on the base 4. One end of the permeation pipe is connected to the bottom of the sample 3 through a porous base plate provided on the top surface of the base 4, and the other end extends to the outside of the base 4. Based on this structure, the permeation channel in the upper loading permeation shaft 1 is connected to the top of the sample 3 through the permeation pressure plate 5, while the permeation pipe on the base 4 is connected to the bottom of the sample 3, thereby forming a complete structure that can achieve normal permeation, allowing the permeation liquid to pass through the sample 3 in a vertical direction under the action of the pressure gradient.

[0030] As a preferred embodiment for realizing multidimensional seepage testing, a seepage channel is provided inside the lateral loading shaft 7; furthermore, the outlet of the seepage channel is located on the end face of the lateral loading shaft 7 that abuts against the sample 3, and a permeation gasket is provided on the end face accordingly, so that the seepage channel inside the lateral loading shaft 7 can be connected to the side of the sample 3. By controlling the fluid pressure inside the two opposing lateral loading shafts 7, a structure for realizing horizontal seepage can be formed.

[0031] Working principle: During the test, the sample 3 is first placed in the center of the confining pressure chamber 2. Then, the external hydraulic system drives the upper loading seepage shaft 1 and the two lateral loading shafts 7 respectively. Since the upper loading seepage shaft 1 and the lateral loading shafts 7 are slidably connected to the loading shaft through holes of the confining pressure chamber 2, the upper loading seepage shaft 1 moves in the vertical direction, applying a vertical load to the sample 3 through the seepage pressure plate 5, while the two lateral loading shafts 7 move in the horizontal direction, applying horizontal loads to the sample 3 in two directions. During this process, the lateral loading balance chamber 6 connected to the lateral loading shaft 7 compensates for the volume change in the loading system by filling it with high-pressure oil, thereby ensuring that the lateral pressure applied to the sample 3 remains constant. Together with the vertical pressure applied by the upper loading seepage shaft 1, it constitutes a precise and controllable true triaxial stress state. At the same time, the confining pressure medium is injected through the confining pressure medium interface of the confining pressure chamber 2, forming a stable confining pressure environment around the sample 3.

[0032] During the seepage test while stress is applied, high-pressure liquid is transported downward through the seepage channel inside the upper loading seepage shaft 1, and is uniformly applied to the top surface of the sample 3 through the seepage pressure plate 5. After the liquid permeates through the sample 3, it is discharged from the seepage pipe at the bottom of the base 4, thus completing the normal seepage test. Alternatively, when conducting the horizontal seepage test, high-pressure liquid is injected into the seepage channel inside the loading shaft 7 from one side, passes laterally through the sample 3, and is discharged from the seepage channel of the loading shaft 7 from the opposite side, thus completing the horizontal seepage test. Throughout the loading and seepage process, the sensor installed on the sensing interface of the confining pressure chamber 2 collects data such as stress, strain, and flow rate in real time. Through this coordinated operation of structure and action, the accurate measurement of multi-directional seepage coupling characteristics under true triaxial stress environment is achieved.

Claims

1. A true triaxial confining pressure seepage test chamber, comprising: Base (4); The confining pressure chamber (2) is fixedly connected to the base (4) above, and the top and side walls of the confining pressure chamber (2) are respectively provided with loading shaft through holes; The sample (3) is placed at the center of the confining pressure chamber (2); The upper loading seepage shaft (1) is slidably connected to the loading shaft through hole at the top of the confining pressure chamber (2), and the upper loading seepage shaft (1) has a seepage channel extending through it along its axial direction inside; and a seepage pressure plate (5) is fixedly connected to the lower end of the upper loading seepage shaft (1) and is used to abut against the top surface of the sample (3); The true triaxial confining pressure seepage test box is characterized by further comprising two lateral loading shafts (7), which are slidably connected to the loading shaft through holes on the side wall of the confining pressure chamber (2), and the axes of the two lateral loading shafts (7) are orthogonal to each other and perpendicular to the axis of the upper loading seepage shaft (1). Furthermore, the true triaxial confining pressure seepage test box also comprises a lateral loading balance chamber (6) corresponding to the lateral loading shafts (7) one by one, and the lateral loading balance chamber (6) is fixedly connected to the end of the lateral loading shaft (7) away from the sample (3).

2. The true triaxial confining pressure seepage test chamber according to claim 1, characterized in that, The true triaxial confining pressure seepage test chamber also includes a test chamber body (8), and the confining pressure chamber (2), the lateral loading shaft (7) and the lateral loading balance chamber (6) are all housed inside the test chamber body (8).

3. The true triaxial confining pressure seepage test chamber according to claim 1, characterized in that, The confining pressure chamber (2) is also provided with a confining pressure medium interface for connecting to an external confining pressure control system.

4. The true triaxial confining pressure seepage test chamber according to claim 3, characterized in that, The confining chamber (2) is also provided with a sensing interface for installing sensors.

5. The true triaxial confining pressure seepage test chamber according to claim 1, characterized in that, The base (4) is provided with a seepage pipe, one end of which is connected to the bottom of the sample (3).

6. The true triaxial confining pressure seepage test chamber according to claim 5, characterized in that, The seepage channel in the upper loading seepage shaft (1) is connected to the top of the sample (3) via the seepage pressure plate (5), and the seepage pipe on the base (4) is connected to the bottom of the sample (3), thereby forming a structure for realizing normal seepage.

7. The true triaxial confining pressure seepage test chamber according to claim 1, characterized in that, The lateral loading shaft (7) has a seepage channel inside.

8. The true triaxial confining pressure seepage test chamber according to claim 7, characterized in that, The seepage channel in the lateral loading shaft (7) is connected to the side of the sample (3) to achieve horizontal seepage.

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