A kind of all-around three-dimensional stress testing device and method based on liquid pressure transmission principle

Abstract

The application relates to a kind of all-around three-dimensional stress testing device and method based on liquid pressure transmission principle, which includes liquid cavity pressure transmission module, involves the deformation induction and stress calculation of each local azimuth, and stress pressure sensing module, which involves the all-around azimuth stress integrated calculation of target measuring point.The liquid cavity pressure transmission module and stress pressure sensing module can make three-dimensional stress calculation cover to each azimuth stress, reduce the stress measurement error caused by the difference of particle size, the anisotropy of soil body and the interference of soil deformation.The improvement of stress testing precision significantly improves the actual data testing efficiency of test, and provides convenience for the fine processing and analysis of soil stress testing data.

Description

A comprehensive three-dimensional stress testing device and method based on the principle of fluid pressure transmission Technical Field

[0001] This application relates to the field of geotechnical testing technology, and in particular to an all-round three-dimensional stress testing device and method based on the principle of liquid pressure transmission. Background Technology

[0002] Previous three-dimensional stress testing methods were based on calculating the conventional stress state at a point in space by subjecting a unit cell to an axial load at a specific orientation angle. This allowed for the convenient acquisition of parameters such as the magnitude of principal stresses, stress invariants, Rhodes parameters, and generalized shear stress. However, in engineering practice, the mechanical response parameters within soil and rock masses exhibit anisotropy, and the in-situ testing environment is inevitably susceptible to interference from complex external factors, leading to significant errors. Furthermore, compared to previous three-dimensional stress testing devices, those used in larger-diameter soil and rock masses (such as slopes and tailings) can better reflect localized stress changes and stress abrupt changes caused by deformation. Based on this, a comprehensive three-dimensional stress testing device and method based on the principle of fluid pressure transmission is proposed. This device can monitor stress data from all directions within a single unit cell, reflecting a more accurate three-dimensional stress state and stress evolution pattern.

[0003] Therefore, in order to better reflect local stress changes and solve the influence of anisotropic mechanical parameters in soil on stress test errors, it is urgent to develop a comprehensive three-dimensional stress testing device and method based on the principle of liquid pressure transmission, so as to achieve refined testing of the three-dimensional stress state changes of soil. Summary of the Invention

[0004] To mitigate stress measurement errors caused by particle size differences, soil anisotropy, and soil deformation interference, and to enable three-dimensional stress calculation to cover all azimuth angles, thereby improving stress testing accuracy and significantly enhancing the efficiency of actual experimental data testing, this application provides a comprehensive three-dimensional stress testing device and method based on the principle of liquid pressure transmission.

[0005] This application provides a comprehensive three-dimensional stress testing device and method based on the principle of liquid pressure transmission.

[0006] The following technical solution is adopted:

[0007] A three-dimensional stress testing device based on the principle of liquid pressure transmission includes a shell component, a liquid cavity, and a pressure sensor. The shell component includes a stainless steel metal frame, a plastic cover, and a rubber diaphragm. The outer contour of the stainless steel metal frame is spherical. The pressure sensor is disposed on the stainless steel metal frame. The rubber diaphragm is adhered to the stainless steel metal frame to form the liquid cavity. There are six liquid cavities. The plastic cover is symmetrically disposed on the upper and lower sides of the spherical stainless steel metal frame.

[0008] By adopting the above technical solution, the shell component consists of a stainless steel metal frame, plastic caps, and a rubber diaphragm. The outer contour of the stainless steel metal frame is spherical, providing a fixed structural framework. Six liquid chambers are formed by bonding the rubber diaphragm to the stainless steel metal frame. These liquid chambers can be used to apply pressure in different directions to simulate the stress of a material or structure in various directions. Pressure sensors are mounted on the stainless steel metal frame to measure the pressure applied in the liquid chambers. By measuring the output of the pressure sensors, the stress on the tested material or structure in different directions can be determined. The plastic caps are symmetrically arranged on the upper and lower sides of the spherical stainless steel metal frame to seal the liquid chambers, ensuring no liquid leakage and providing a means of applying pressure.

[0009] Optionally, the housing component further includes an L-shaped groove, side flanges, bolts, screws, through holes, and internally threaded holes. The L-shaped groove is located on the edge side plate of the stainless steel metal frame. The rubber membrane is adhered to the L-shaped groove. The plastic cap is inserted into the L-shaped groove for installation. The side flanges are located on the frame of the stainless steel metal frame. The through holes are located on the side flanges. The side flanges overlap each other and are fastened along the through holes with bolts. The internally threaded holes are located at the edge of the plastic cap. After clamping the rubber membrane, the plastic cap is connected to the stainless steel metal frame through the internally threaded holes and the screws.

[0010] By adopting the above technical solution, an L-shaped groove is provided on the edge side plate of the stainless steel metal frame for fixing the rubber diaphragm. The rubber diaphragm is adhered to the L-shaped groove to ensure a sealed connection with the stainless steel metal frame. A plastic cap is inserted into the L-shaped groove for installation, clamping the rubber diaphragm to ensure the airtightness of the liquid chamber. Internally threaded holes are located at the edge of the plastic cap for connection with screws, further reinforcing the structure of the liquid chamber. Side flanges are provided on the frame of the stainless steel metal frame, overlapping each other and fastened with bolts through through holes. The main function of these side flanges is to enhance the structural strength of the device, ensuring that the device will not deform or break under pressure.

[0011] Optionally, the liquid chamber includes an injection hole, an overflow hole, and a metal gasket. The injection hole is located in the liquid chamber and is used to inject hydraulic oil into the liquid chamber. The overflow hole is located in the liquid chamber, and the metal gasket and the screw seal the overflow hole and the injection hole.

[0012] By employing the above technical solution, the injection port is located in the liquid chamber and is used to inject hydraulic oil into the liquid chamber. By injecting hydraulic oil, pressure can be built into the liquid chamber, thereby applying pressure to the material or structure under test to simulate the effect of external stress. The overflow port is also located in the liquid chamber and is used to control the flow of hydraulic oil within the liquid chamber. The overflow port is typically combined with a metal gasket and a screw. By adjusting the tightness of the screw, the pressure in the liquid chamber can be controlled, and the pressure can be safely released after the test. The metal gasket and screw are used to seal the overflow port and injection port, ensuring that the liquid does not leak. The metal gasket provides additional sealing, while the screw is used to secure the metal gasket to prevent pressure release or liquid leakage.

[0013] Optionally, the pressure sensor includes a pressure sensor connecting wire, a gland connector, and a plug. The pressure sensor connecting wire is connected to the pressure sensor and leads out from the center hole of one side of the sphere. The gland connector is located on the plastic cap and communicates with the center hole. The pressure sensor connecting wire passes through the gland connector and is locked therein. The plug is located at the center hole on the other side for sealing.

[0014] By adopting the above technical solution, the pressure sensor connection cable connects to the pressure sensor and exits from the central hole of the sphere, allowing the pressure sensor to be connected to external devices. This connection cable exits through the central hole, avoiding direct exposure of the sensor connection cable in the pressure environment created within the liquid chamber, thus protecting the integrity and stability of the connection cable. The gland connector is located on the plastic cap and communicates with the central hole of the sphere. This connector allows the pressure sensor connection cable to pass through and provides a sealed channel to prevent liquid leakage or contamination of the sensor connection cable. A plug is located on the other side of the central hole of the sphere to seal the orifice. This plug ensures that liquid does not leak from the central hole and also protects the pressure sensor connection cable and the gland connector.

[0015] Optionally, an all-around three-dimensional stress testing device based on the principle of fluid pressure transmission includes the following steps:

[0016] S1. Install the pressure sensor in the housing component and firmly attach it with adhesive. The area around the pressure sensor should be fully filled with adhesive, and there should be no pores, cracks, or obstruction of the pressure-sensing surface.

[0017] S2. Use adhesive to bond the spherical curved rubber film to the L-shaped groove inside the stainless steel metal frame. The adhesive seam should be tight and straight, and close to the bend of the L-shaped groove to ensure airtightness.

[0018] S3. After the shell component adheres to the rubber diaphragm and the interior is closed to form a liquid cavity, hydraulic oil is injected into the liquid cavity through the injection hole until hydraulic oil overflows from the overflow hole. Then, the overflow hole is sealed with screws and metal washers. Injection continues, and the curvature of the rubber diaphragm is constantly observed during the process. Injection can be stopped when the curvature becomes a spherical curvature. Then, the injection hole is sealed with screws and metal washers.

[0019] S4, lead the sensor connection line out from the center hole on one side, then overlap the side flange plates between the housing components and tighten the bolts to make the device spherical and stable as a whole;

[0020] S5. The device is divided into upper and lower parts and each is fitted with a plastic cover. The groove on the side plate of the plastic cover can fit into the L-shaped groove. After the plastic cover is embedded in the stainless steel metal frame, it is firmly connected to the stainless steel metal frame with screws. This can further improve the sealing performance of the liquid chamber by compressing and sealing the rubber membrane.

[0021] S6, the sensor connection wire is locked with a gland connector, the gland connector is threaded to the top hole of the plastic cover, and the other side of the center hole is threaded to the plastic cover with a plug, so as to achieve the effect of sealing and waterproofing inside the device.

[0022] S7. After the device is assembled, the pressure of each liquid chamber needs to be calibrated, and the internal liquid pressure caused by the slight deformation of the rubber diaphragm needs to be zeroed.

[0023] S8. After the assembly and calibration preparations are completed, the setup can be carried out according to different working conditions. For example, if the medium in the test environment is fine-grained soil or liquid, it can be set up directly. If the medium in the test environment is gravel or engineering waste, the need for protective measures should be determined based on the sharpness of the loose particles. In addition, if the test environment is in the grouting hole of a tunnel, soil sidewall, pile foundation, or any concrete hook, protective measures must be taken. The protective measures can be achieved by filling a certain thickness of fine sand, plastic particles, or other media around the device to protect it.

[0024] By adopting the above technical solution, the pressure sensor is installed (S1): ensuring that the sensor is firmly bonded to the housing component, and that the adhesive filling the surrounding area ensures the sealing and integrity of the sensor; the rubber diaphragm is bonded (S2): using adhesive, the spherical curved rubber diaphragm is bonded to the L-shaped groove inside the metal frame to ensure the sealing of the liquid chamber; hydraulic oil is injected (S3): hydraulic oil is injected into the liquid chamber through the injection hole, and the degree of hydraulic oil filling is determined by observing the curvature change of the rubber diaphragm to ensure that the pressure inside the liquid chamber meets the requirements; the housing component is assembled (S4): the sensor connection wire is led out and bolted to ensure that the entire device is stable and secure, ensuring the accuracy of the test; the plastic is installed. Sealing (S5): Install plastic caps and connect them to the metal frame with screws to further improve the sealing of the liquid chamber; Locking sensor connection wires (S6): Lock the sensor connection wires with gland connectors and achieve a sealed and waterproof effect inside the device through plugs, protecting the device from the influence of the external environment; Pressure calibration (S7): Perform pressure calibration on each liquid chamber to ensure the accuracy of the test results, and at the same time, zero out the internal liquid pressure caused by slight deformation of the rubber diaphragm; Arrangement work (S8): Arrange the work according to different working conditions, and take protective measures when necessary, such as filling the test environment with fine sand, plastic particles and other media to protect the device from the influence of the external environment.

[0025] Optionally, the three-dimensional stress testing device contains at least six liquid chambers, each corresponding to an area force in one of the six directions. The axial stress on a local spherical surface of the rubber membrane is collected by the pressure sensor via liquid pressure transmission, and the resulting spatial area force... as follows:

[0026] (1)

[0027] in, A pressure sensor embedded inside a stainless steel frame collects stress data; A C This represents the surface area of ​​the pressure-sensitive surface of the current liquid cavity; Axial pressure is distributed on the curved surface of the rubber membrane; Let be the area of ​​the spherical element on the rubber membrane; i represents the i-th liquid cavity (i=1,2,……,6).

[0028] By adopting the above technical solution This represents the stress collected by a pressure sensor embedded inside the stainless steel frame. This is the pressure within the liquid chamber measured by the pressure sensor, representing the magnitude of the force within that chamber. A C This represents the surface area of ​​the pressure-sensitive surface in the current liquid chamber. This is the area on the surface of the rubber membrane inside the liquid chamber; the shape and size of the liquid chamber affect the surface area of ​​the pressure-sensitive surface. This represents the axial pressure distributed on the curved surface of the rubber diaphragm. This is the pressure exerted by the hydraulic oil inside the fluid chamber on the rubber diaphragm, transmitted to the curved surface of the rubber diaphragm through fluid pressure transmission. This represents the area of ​​a spherical infinitesimal element on the rubber membrane. This is achieved by discretizing the surface using calculus, dividing the surface into small infinitesimal elements to calculate the pressure on each element.

[0029] Optionally, a spatial reference coordinate system is established with the center of the test device sphere as the origin O, and equation (1) is further expanded:

[0030] (2)

[0031] in, A pressure sensor embedded inside a stainless steel frame collects stress data; A C This represents the surface area of ​​the pressure-sensitive surface of the current liquid cavity; , , Let be the orientation cosine of the axial load distributed on the surface of the i-th liquid cavity; , , , , , represents the conventional stress component at the origin O of the spatial reference coordinate system; i represents the i-th liquid cavity (i=1,2,……,6); Let be the area of ​​the spherical element on the rubber membrane.

[0032] By adopting the above technical solution This represents the stress collected by a pressure sensor embedded inside the stainless steel frame. It indicates the magnitude of the force corresponding to the pressure within the liquid chamber of the testing device. A C This represents the surface area of ​​the pressure-sensitive surface in the current liquid cavity. The shape and size of the liquid cavity affect the surface area of ​​the pressure-sensitive surface. , , These represent the orientation cosines of the axial load distributed on the surface of the i-th liquid cavity. These orientation cosines indicate the stress direction within each liquid cavity. , , , , , represents the conventional stress components at the origin O of the spatial reference coordinate system. These components represent the stress magnitude in each direction within the spatial reference coordinate system. 'i' represents the area of ​​a spherical infinitesimal element on the rubber membrane. This is achieved by discretizing the surface using calculus, dividing the surface into small infinitesimal elements to calculate the pressure on each element.

[0033] Optionally, based on the azimuth angle range of the spherical surface on each liquid cavity and the pressure collected by the pressure sensor, the conventional stress components in the rectangular coordinate system are calculated. First, equation (2) is expressed as:

[0034] (3)

[0035] in, = , , , , , ; This represents the surface area of ​​the pressure-sensitive surface of the current liquid cavity; Let be the area of ​​the spherical element on the rubber membrane; i represents the i-th liquid cavity (i=1,2,……,6); It is a column vector composed of stresses collected by i pressure sensors; ( , , ) The integral coefficient matrix of the coordinate system is ∏n×6; ti( , , ) represents the elements within the coefficient matrix.

[0036] To obtain the conventional stress components, equation (3) is further expressed as:

[0037] (4)

[0038] in,[ ] is a column vector composed of stresses collected by n pressure sensors; ]=[ , , , , , T represents the conventional stress component; A C is the surface area of ​​the pressure-sensitive surface of the current liquid cavity; π-1 is the inverse transformation form of the function matrix, which requires an accurate spherical azimuth angle interval to obtain the numerical matrix and perform the inverse transformation.

[0039] By adopting the above technical solution, [ ]=[ , , , , , [T] represents a column vector composed of conventional stress components, indicating the magnitude of stress in each direction in the spatial reference coordinate system. A C This represents the surface area of ​​the pressure-sensitive surface in the current liquid cavity. The shape and size of the liquid cavity affect the surface area of ​​the pressure-sensitive surface. This represents the area of ​​a spherical infinitesimal element on the rubber membrane. This is achieved by discretizing the surface using calculus, dividing the surface into small infinitesimal elements to calculate the pressure on each element. ∏n×6;ti( , , ) are the elements within the coefficient matrix. These elements are determined by the azimuth angle interval of the sphere on the liquid cavity and are used to calculate the integral coefficient matrix. ( , , ) This is the integral coefficient matrix, which is the function matrix calculated based on the azimuth angle interval of the sphere on the liquid cavity. The inverse transformation form of the integral coefficient matrix is ​​∏⁻¹, used to solve for conventional stress components. ] is a column vector composed of stresses collected by n pressure sensors.

[0040] In summary, this application includes at least one of the following beneficial technical effects:

[0041] 1. The housing consists of a stainless steel frame, plastic caps, and a rubber diaphragm. The stainless steel frame has a spherical outer profile, providing a fixed structural framework. Six liquid chambers are formed by bonding the rubber diaphragm to the stainless steel frame. These chambers can be used to apply pressure in different directions to simulate the stress on a material or structure in various directions. Pressure sensors are mounted on the stainless steel frame to measure the pressure applied in the liquid chambers. By measuring the output of the pressure sensors, the stress on the tested material or structure in different directions can be determined. The plastic caps are symmetrically positioned on the upper and lower sides of the spherical stainless steel frame to seal the liquid chambers, ensuring no leakage and providing a means of applying pressure.

[0042] 2. Install the pressure sensor (S1): Ensure the sensor is firmly bonded to the housing component, and that the adhesive filling around it ensures a tight seal and sensor integrity; Attach the rubber diaphragm (S2): Use adhesive to attach the spherical curved rubber diaphragm to the L-shaped groove inside the metal frame to ensure the liquid chamber is sealed; Inject hydraulic oil (S3): Inject hydraulic oil into the liquid chamber through the injection hole, and determine the degree of hydraulic oil filling by observing the curvature change of the rubber diaphragm, ensuring the internal pressure of the liquid chamber meets the requirements; Assemble the housing component (S4): Lead out the sensor connection wire and tighten the bolts to ensure the overall stability and accuracy of the device; Install the plastic cap (S5). ): Install plastic caps on each liquid chamber and connect them to the metal frame with screws to further improve the sealing of the liquid chamber; Lock the sensor connection line (S6): Lock the sensor connection line with a gland connector and achieve a sealed and waterproof effect inside the device through the plug, protecting the device from the influence of the external environment; Pressure calibration (S7): Perform pressure calibration on each liquid chamber to ensure the accuracy of the test results, and at the same time, zero out the internal liquid pressure caused by the slight deformation of the rubber diaphragm; Arrange the work (S8): Arrange the work according to different working conditions, and take protective measures when necessary, such as filling the test environment with fine sand, plastic particles and other media to protect the device from the influence of the external environment;

[0043] 3.[ ]=[ , , , , , [T] represents a column vector composed of conventional stress components, indicating the magnitude of stress in each direction in the spatial reference coordinate system. A C This represents the surface area of ​​the pressure-sensitive surface in the current liquid cavity. The shape and size of the liquid cavity affect the surface area of ​​the pressure-sensitive surface. This represents the area of ​​a spherical infinitesimal element on the rubber membrane. This is achieved by discretizing the surface using calculus, dividing the surface into small infinitesimal elements to calculate the pressure on each element. ∏n×6;ti( , , ) are the elements within the coefficient matrix. These elements are determined by the azimuth angle interval of the sphere on the liquid cavity and are used to calculate the integral coefficient matrix. ( , , ) This is the integral coefficient matrix, which is the function matrix calculated based on the azimuth angle interval of the sphere on the liquid cavity. The inverse transformation form of the integral coefficient matrix is ​​∏⁻¹, used to solve for conventional stress components. ] is a column vector composed of stresses collected by n pressure sensors. Attached Figure Description

[0044] Figure 1 is a schematic diagram of the structure of the all-round three-dimensional stress testing device and calculation method based on the principle of liquid pressure transmission according to an embodiment of this application;

[0045] Figure 2 is a component assembly view of the all-round three-dimensional stress testing device and calculation method based on the principle of liquid pressure transmission according to an embodiment of this application;

[0046] Figure 3 is a schematic diagram of the azimuth layout according to an embodiment of the present invention.

[0047] Explanation of reference numerals in the attached drawings: 1. Shell component; 101. Stainless steel metal frame; 102. Plastic cover; 103. Rubber diaphragm; 104. L-shaped groove; 105. Side flange plate; 106. Bolt; 107. Screw; 108. Through hole; 109. Internal threaded hole; 2. Liquid chamber; 201. Injection hole; 202. Overflow hole; 203. Metal gasket; 3. Pressure sensor; 301. Pressure sensor connecting wire; 302. Gland connector; 303. Plug. Detailed Implementation

[0048] The present application will be further described in detail below with reference to Figures 1-3.

[0049] This application discloses an all-around three-dimensional stress testing device and method based on the principle of liquid pressure transmission.

[0050] Referring to Figures 1 and 2, a comprehensive three-dimensional stress testing device and method based on the principle of liquid pressure transmission includes a shell component 1, a liquid chamber 2, and a pressure sensor 3. The shell component 1 includes a stainless steel metal frame 101, a plastic cap 102, and a rubber diaphragm 103. The shell component 1, composed of the stainless steel metal frame 101, plastic cap 102, and rubber diaphragm 103, has a simple and reliable structure. The stainless steel metal frame 101 serves as the main structural support, providing a stable framework, while the plastic cap 102 ensures the sealing of the liquid chamber 2 and ease of operation. The device is designed with six liquid chambers 2, distributed in different directions of the sphere, capable of applying pressure in different directions. This design allows for the simulation of stresses on materials or structures in various directions, thereby providing a more comprehensive evaluation of their performance and behavior. The pressure sensor 3 is mounted on the stainless steel metal frame 101 and is used to measure the pressure applied in the liquid chambers 2. This allows for real-time monitoring of pressure changes and accurate recording of pressure data, thus providing a better understanding of the stress conditions of the tested material or structure. Plastic caps 102 are symmetrically positioned on the upper and lower sides of the sphere within the stainless steel frame 101 to seal the liquid chamber 2, ensuring no liquid leakage and providing a means of applying pressure. This design is simple yet effective, facilitating operation and maintenance.

[0051] Referring to Figures 1 and 2, the housing component 1 also includes an L-shaped groove 104, a side flange plate 105, a bolt 106, a screw 107, a through hole 108, and an internally threaded hole 109. The L-shaped groove 104 is located on the edge side plate of the stainless steel metal frame 101 and is used to fix the rubber diaphragm 103. The rubber diaphragm 103 is adhered to the L-shaped groove 104, ensuring a sealed connection with the stainless steel metal frame 101 and preventing liquid leakage. The plastic cap 102 is inserted into the L-shaped groove 104 for installation, and by clamping the rubber diaphragm 103, it ensures the sealing of the liquid chamber 2. This design is simple and effective, ensuring the sealing and stability of the liquid chamber 2. The internally threaded hole 109 is located at the edge of the plastic cap 102 and is used to connect with the screw 107, further reinforcing the structure of the liquid chamber 2. This design makes the assembly of the device more stable and able to withstand the pressure inside the liquid chamber 2 without deformation or rupture. Side flanges 105 are mounted on the frame of the stainless steel metal frame 101, overlapping each other and fastened with bolts 106 through through holes 108. The main function of these side flanges 105 is to enhance the structural strength of the device, ensure that the device will not deform or break under pressure, and improve the stability and durability of the device.

[0052] Referring to Figures 1 and 2, the liquid chamber 2 includes an injection port 201, an overflow port 202, and a metal gasket 203. The injection port 201, located in the liquid chamber 2, is used to inject hydraulic oil into the liquid chamber 2. Injecting hydraulic oil establishes pressure in the liquid chamber 2 to simulate the effect of external stress. By controlling the amount and speed of the injected hydraulic oil, the pressure within the liquid chamber 2 can be precisely adjusted, thereby applying different levels of pressure to the tested material or structure. The overflow port 202, located in the liquid chamber 2, is used to control the flow of hydraulic oil within the liquid chamber 2. Typically, when the pressure within the liquid chamber 2 exceeds a set value, the overflow port 202 releases the overpressure, thus protecting the device and the tested material or structure from damage. The metal gasket 203 and the screw 107 are used to seal the overflow port 202 and the injection port 201, ensuring that the liquid does not leak. The metal gasket 203 provides additional sealing to prevent liquid leakage through the overflow port 202 and the injection port 201. Screw 107 is used to secure the metal gasket 203, ensuring the stability of the seal and preventing pressure release or liquid leakage.

[0053] Referring to Figures 1 and 2, the pressure sensor 3 includes a pressure sensor connection cable 301, a gland connector 302, and a plug 303. The pressure sensor connection cable 301 connects to the pressure sensor 3 and extends from the center hole of the sphere. This connection cable allows the pressure sensor 3 to connect to external devices to transmit acquired pressure data. By extending from the center hole of the sphere, the connection cable avoids direct exposure to the pressure environment of the liquid chamber 2, protecting the integrity and stability of the connection cable while reducing the risk of potential damage. The gland connector 302 is located on the plastic cap 102 and connects to the center hole of the sphere. This connector allows the pressure sensor connection cable 301 to pass through and provides a sealed channel to prevent liquid leakage or contamination of the sensor connection cable. The design of the gland connector 302 ensures the safe transmission of the connection cable while ensuring the sealing and stability of the device. The plug 303 is located on the other side of the center hole of the sphere and is used to seal the orifice. This plug 303 ensures that liquid does not leak from the center hole and also protects the pressure sensor connection cable 301 and the gland connector 302. The use of plugs ensures the stability and safety of the device during testing, preventing liquid leakage or contamination of the sensor connection lines.

[0054] Referring to Figures 1 and 2, install the pressure sensor (S1): Install the pressure sensor 3 in the housing component 1, ensuring it is firmly bonded. The adhesive filling around the sensor should be full and free of air holes, cracks, or obstructions to the pressure-sensing surface to ensure the sensor's sealing and integrity. Adhere the rubber diaphragm (S2): Use adhesive to bond the spherical curved rubber diaphragm to the L-shaped groove 104 inside the stainless steel metal frame 101. The adhesive seam should be tight and straight, close to the bend of the L-shaped groove 104 to ensure the sealing of the liquid chamber 2. Inject hydraulic oil (S3): Inject hydraulic oil into the liquid chamber 2 through the injection hole 201 until hydraulic oil overflows from the overflow hole 202. Then, use screws 107 and metal washers 203 to seal the overflow hole 202. During the injection process, observe the changes in the curvature of the rubber diaphragm 103 until the curvature becomes spherical; Assemble the housing components (S4): Lead the sensor connection line out from the center hole on one side, then overlap the side flanges 105 between the housing components 1 and tighten them with bolts 106 to make the device as a whole stable and secure, so as to ensure the accuracy of the test; Install the plastic caps (S5): Install the plastic caps 102 respectively, ensuring that the grooves on the side plates of the caps fit with the L-shaped grooves 104. After the plastic cap 102 is embedded in the stainless steel frame 101, it is securely connected to the stainless steel frame 101 using screws 107 to further improve the sealing of the liquid chamber 2; Locking the sensor connection line (S6): The sensor connection line is locked by the gland connector 302. The gland connector 302 is threaded to the top hole of the plastic cap 102, and the other side of the center hole is threaded to the plastic cap 102 by the plug 303, achieving a sealed and waterproof effect inside the device; Pressure calibration (S7): Pressure calibration is performed on each liquid chamber 2 to ensure the accuracy of the test results. At the same time, the internal liquid pressure caused by the slight deformation of the rubber diaphragm 103 is zeroed to ensure the accuracy and reliability of the test; Arrangement work (S8): Arrangement work is carried out according to different working conditions, and protective measures are taken when necessary, such as filling the test environment with fine sand, plastic particles, etc., to protect the device from the influence of the external environment and ensure the smooth progress of the test.

[0055] Referring to Figure 3, the pressure-bearing spherical surface of the rubber membrane 103 is used as the measurement range, and a spatial coordinate system is established with the center of the sphere as the origin O, as shown in Figure 3. Then, the azimuth angle interval of the spherical surface is measured. l, m, and n are defined as the azimuth cosine values ​​of the azimuth direction and the coordinate axes (x, y, z), i.e., the azimuth cosine. Furthermore, the following is defined... The azimuth direction is in The angle between the projection of the plane and the x-axis. This is the angle between the azimuth direction and the z-axis, and the azimuth cosine value is as follows:

[0056]

[0057] (1)

[0058]

[0059] Where l, m, and n are azimuth cosines; The azimuth direction is in The angle between the projection of the plane and the x-axis; This is the angle between the azimuth direction and the z-axis.

[0060] By transmitting pressure through liquid, the axial stress on a local spherical surface of the rubber diaphragm can be collected by a pressure sensor, thus obtaining the spatial area force. as follows:

[0061] (2)

[0062] in, A pressure sensor embedded inside a stainless steel frame collects stress data; A C This represents the surface area of ​​the pressure-sensitive surface of the current liquid cavity; Axial pressure is distributed on the curved surface of the rubber membrane; Let be the area of ​​the spherical element on the rubber membrane; i represents the i-th liquid cavity (i=1,2,……,6).

[0063] Based on the established system coordinate system in Figure 3, equation (2) can be further expanded:

[0064] (3)

[0065] in, A pressure sensor embedded inside a stainless steel frame collects stress data; A C This represents the surface area of ​​the pressure-sensitive surface of the current liquid cavity; , , Let be the orientation cosine of the axial load distributed on the surface of the i-th liquid cavity; , , , , , represents the conventional stress component at the origin O of the spatial reference coordinate system; i represents the i-th liquid cavity (i=1,2,……,6); Let be the area of ​​the spherical element on the rubber membrane.

[0066] Based on the azimuth range of the curved spherical surface measured in Figure 3 and the pressure collected by the pressure sensor, the conventional stress components in the rectangular coordinate system can be calculated. First, equation (3) is expressed as:

[0067] (4)

[0068] in, = , , , , , For conventional stress components; A C This represents the surface area of ​​the pressure-sensitive surface of the current liquid cavity; Let be the area of ​​the spherical element on the rubber membrane; i represents the i-th liquid cavity (i=1,2,……,6); It is a column vector composed of stresses collected by i pressure sensors; ( , , ) The integral coefficient matrix of the coordinate system is ∏n×6; ti( , , ) represents the elements within the coefficient matrix.

[0069] As shown in Figure 3, the area of ​​the infinitesimal element of the spherical surface. It can be represented as:

[0070] (5)

[0071] Where r is the spherical radius of the device; The azimuth direction is in The angle between the projection of the plane and the x-axis; This is the angle between the azimuth direction and the z-axis.

[0072] Combining equations (1), (4), and (5), the elements within the coefficient matrix can be represented as follows:

[0073] A=

[0074] B=

[0075] C=

[0076] D=

[0077] E=

[0078] F= (6)

[0079] in, , , Let r be the orientation cosine of the axial load distributed on the surface of the i-th liquid cavity; r is the spherical radius of the device. The azimuth direction is in The angle between the projection of the plane and the x-axis; This is the angle between the azimuth direction and the z-axis; Let the area of ​​the spherical element on the rubber membrane be denoted as .

[0080] As shown in Figure 3, the azimuth interval is ∈[29°, 87°]、 ∈[5° , 115°], we can obtain A=0.5998r2, B=0.7161r2, C=0.5962r2, D=0.4877r2, E=0.5631r2, F=1.0034r2 (retain four decimal places) by definite integration according to equation (6). Similarly, by referring to the same spatial coordinate system, we measure the azimuth angles of the other five blocks of the shell in Figure 1, and calculate the elements in the coefficient matrix of the other blocks according to equation (6);

[0081] Based on the measured azimuth angle ranges of each shell segment, calculate the pressure-sensing surface area A of the liquid cavity. C for

[0082] (7)

[0083] Where r is the spherical radius of the device; The azimuth direction is in The angle between the projection of the plane and the x-axis; This is the angle between the azimuth direction and the z-axis.

[0084] Finally, according to calculation step 8), substitute equations (6) and (7) into equation (4) to obtain the conventional stress components at the measuring point where the device is located. ]:

[0085] (8)

[0086] in,[ ] is a column vector composed of stresses collected by n pressure sensors; ]=[ , , , , , T represents the conventional stress component; A C U is the pressure-sensitive surface area of ​​the current liquid cavity; U-1 is the inverse transformation form of the numerical coefficient matrix calculated by equation (6). The numerical matrix can only be obtained and inverse transformation can be performed by accurately calculating the spherical azimuth angle interval.

[0087] The implementation principle of the omnidirectional three-dimensional stress testing device and method based on the principle of liquid pressure transmission in this application is as follows:

[0088] This invention provides an omnidirectional three-dimensional stress testing device and method based on the principle of liquid pressure transmission. It quantifies the axial compression borne by curved areas at certain azimuth angles through liquid pressure transmission, thereby indirectly and conveniently achieving accurate and gridded stress acquisition across all directions. This enables three-dimensional stress calculation to cover all azimuth angles, facilitating the refined processing and analysis of soil stress test data. Furthermore, the above description is only for illustration in conjunction with the fabrication process. The omnidirectional three-dimensional stress testing device based on the principle of liquid pressure transmission provided by this invention consists of only six partitions, and the calculation method is described based on this. This allows for highly convenient assembly, testing, and maintenance.

[0089] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A three-dimensional omnidirectional stress testing device based on the principle of liquid pressure transmission, characterized in that, include: The housing component (1), liquid chambers (2), and pressure sensors (3) are provided. The housing component (1) includes a stainless steel metal frame (101), a plastic cap (102), and a rubber diaphragm (103). The outer contour of the stainless steel metal frame (101) is spherical. The pressure sensor (3) is mounted on the stainless steel metal frame (101). The rubber diaphragm (103) is adhered to the stainless steel metal frame (101) to form the liquid chambers (2). There are six liquid chambers (2). The plastic caps (102) are symmetrically arranged on the upper and lower sides of the sphere of the stainless steel metal frame (101). The housing component (1) also includes an L-shaped groove (104), a side flange plate (105), bolts (106), screws (107), a through hole (108), and an internal threaded hole (109). The L-shaped groove (104) is provided on the edge side plate of the stainless steel metal frame (101). The rubber membrane (103) is bonded to the L-shaped groove (104) by adhesive. The plastic cover (102) is installed by snapping into the L-shaped groove (104). The side flange plate (105) is provided on the frame of the stainless steel metal frame (101). The through hole (108) is provided on the side flange plate (105). The side flange plates (105) overlap each other and are fastened along the through hole (108) with the bolt (106). The internal thread hole (109) is provided at the edge of the plastic cover (102). After the plastic cover (102) clamps the rubber membrane (103), it is connected to the stainless steel metal frame (101) through the internal thread hole (109) and the screw (107).

2. The omnidirectional three-dimensional stress testing device based on the principle of liquid pressure transmission according to claim 1, characterized in that: The liquid chamber (2) includes an injection hole (201), an overflow hole (202), and a metal gasket (203). The injection hole (201) is located in the liquid chamber (2) and is used to inject hydraulic oil into the liquid chamber (2). The overflow hole (202) is located in the liquid chamber (2). The metal gasket (203) and the screw (107) seal the overflow hole (202) and the injection hole (201).

3. The omnidirectional three-dimensional stress testing device based on the principle of liquid pressure transmission according to claim 2, characterized in that: The pressure sensor (3) includes a pressure sensor connecting wire (301), a gland connector (302), and a plug (303). The pressure sensor connecting wire (301) is connected to the pressure sensor (3) and leads out from the center hole of one side of the sphere. The gland connector (302) is located on the plastic cap (102) and communicates with the center hole. The pressure sensor connecting wire (301) passes through the gland connector (302) and is locked by it. The plug (303) is located at the center hole on the other side for sealing.

4. The omnidirectional three-dimensional stress testing device based on the principle of liquid pressure transmission according to claim 2, characterized in that, The installation method includes the following steps: S1, install the pressure sensor (3) in the housing component (1) and firmly adhere it with adhesive. The pressure sensor (3) should be fully filled with adhesive around its perimeter, and there should be no air holes, cracks, or obstruction of the pressure-sensing surface; S2, use adhesive to adhere the spherical curved rubber diaphragm (103) to the L-shaped groove (104) inside the stainless steel metal frame (101). The adhesive joint should be tight and straight, and close to the bend of the L-shaped groove (104) to ensure sealing; S3, wait for the housing component (1) and the rubber diaphragm (103) to adhere to the housing component (1) and the rubber diaphragm (103) to adhere to the housing component (1) and the housing component (1) to adhere to the housing component (1) and the housing component (103 ... After the adhesion closes the interior to form a liquid cavity (2), hydraulic oil is injected into the liquid cavity (2) through the injection hole (201) until hydraulic oil overflows from the overflow hole (202). Then, the overflow hole (202) is sealed with a screw (107) and a metal gasket (203). Then, injection continues, and the curvature of the rubber diaphragm (103) is constantly observed during the process. The injection can be stopped when the curvature becomes a spherical curvature. Then, the injection hole (201) is sealed with a screw (107) and a metal gasket (203). S4, the pressure sensor connection wire (301) is connected from A central hole is led out from one side, and then the side flanges (105) between the shell components (1) are overlapped and bolted (106) to make the device spherical and stable as a whole; S5, the device is divided into upper and lower parts and plastic covers (102) are installed on them respectively. The groove on the side plate of the plastic cover (102) can fit with the L-shaped groove (104). After the plastic cover (102) is embedded in the stainless steel metal frame (101), screws (107) are used to firmly connect it to the stainless steel metal frame (101), so that the rubber membrane (103) can be compressed and sealed. After sealing, the sealing performance of the liquid chamber (2) is further improved; S6, the pressure sensor connection line (301) is locked by the gland connector (302), the gland connector (302) is threaded to the top hole of the plastic cap (102), and the other side of the center hole is threaded to the plastic cap (102) by the plug (303), so as to achieve the effect of sealing and waterproofing inside the device; S7, after the device is assembled, the pressure of each liquid chamber (2) needs to be calibrated, and the internal liquid pressure caused by the slight deformation of the rubber diaphragm (103) is zeroed.

5. The omnidirectional three-dimensional stress testing device based on the principle of liquid pressure transmission according to claim 4, characterized in that: The three-dimensional stress testing device contains at least 6 liquid chambers, each corresponding to an area force in 6 directions. The axial stress on the local spherical surface of the rubber membrane (103) is collected by the pressure sensor (3) through liquid pressure transmission.

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