An indoor test device and method for simulating stress environment of geotechnical test piece in coordination

Abstract

The present application relates to geotechnical engineering mechanics test equipment technical field, disclose a kind of indoor test device and method of geotechnical test piece stress environment collaborative simulation;Including environment simulation module, mechanics loading module and collaborative control module;Environment simulation module includes maintenance box, solution tank and solution circulation assembly, the solution circulation assembly is communicated with the outside of the solution tank, the solution tank is fixedly connected in the inside of the maintenance box;Mechanics loading module is set in the solution tank, the mechanics loading module includes test module device, the test module device is used to accommodate test piece, the test module device includes axial loading assembly and confining pressure loading assembly, the confining pressure loading assembly includes water-permeable restraint mesh cloth and stretching mechanism, the water-permeable restraint mesh cloth outside is connected with the stretching mechanism.The present application realizes stress and fluid penetration synchronous simulation by using water-permeable restraint mesh cloth and servo stretching device, and completes confining pressure dynamic compensation and nondestructive evaluation in combination with photoelectric measurement and prediction model.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering mechanics testing equipment technology, specifically to an indoor testing device and method for co-simulating the stress environment of geotechnical specimens. Background Technology

[0002] In the process of deep underground engineering construction and underground resource extraction, rock and soil masses are usually in a high ground stress and complex groundwater chemical environment. In order to study the mechanical properties and deterioration law of rock and soil materials under these complex conditions, it is necessary to simulate their real stress and environmental conditions through indoor test equipment.

[0003] Existing indoor testing equipment has certain limitations in simulating the coupling of stress and fluid environment. Traditional triaxial testing equipment generally uses a sealed rubber sleeve to completely enclose the soil and rock specimen in order to apply stable lateral confining pressure. This physical isolation structure blocks the direct contact between the external fluid medium and the specimen surface, which means that while the specimen is subjected to complex geostress, it cannot simultaneously undergo the infiltration of groundwater and the dissolution process of chemical substances, making it difficult to truly reproduce the multi-field coupling environment in deep strata. Due to this structural limitation, engineers usually adopt a step-by-step testing method, that is, first immerse the specimen in a specific solution for a long time in static immersion until it reaches the preset corrosion level, and then take it out and put it into a mechanical testing machine for destructive testing. This method interrupts the dynamic evolution process of the mutual promotion between mechanical stress damage and chemical medium deterioration.

[0004] During long-term compressive stress and immersion in media, the internal microstructure of soil and rock materials changes, accompanied by nonlinear volume expansion or corrosion shrinkage deformation. Most existing mechanical loading devices perform static loading based on initially set fixed parameters, lacking a boundary stress compensation mechanism based on the evolution of environmental physicochemical parameters and specimen deformation feedback. This can lead to the actual stress state deviating from the set target confining pressure in the later stages of the test. At the same time, when monitoring the mechanical degradation characteristics of soil and rock materials, the conventional method is to attach contact strain sensors to the specimen surface. However, these sensors and their cables may short-circuit or corrode and fall off under long-term immersion in acidic or saline solutions. This means that the test process often only obtains the macroscopic mechanical strength at the final failure of the specimen, making it difficult to achieve continuous and non-destructive monitoring of the progressive reduction process of mechanical properties such as the elastic modulus of materials in multiphase fluid environments. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an indoor testing device and method for co-simulating the stress environment of geotechnical specimens. This solves the problems of existing testing devices being unable to simultaneously simulate multiaxial stress and fluid permeation coupling due to their sealed enclosure, and lacking dynamic stress compensation and non-destructive monitoring under corrosive environments.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides an indoor testing apparatus for co-simulating the stress environment of soil and rock specimens, comprising: The environmental simulation module includes a curing chamber, a solution tank, and a solution circulation component. The solution tank is connected to the outside of the solution circulation component and is fixedly connected to the inside of the curing chamber. A mechanical loading module is set inside the solution tank. The mechanical loading module includes a mold device for accommodating the specimen block. The mold device includes an axial loading component and a confining pressure loading component. The confining pressure loading component includes a permeable constraint mesh and a tensioning mechanism. The tensioning mechanism is connected to the outside of the permeable constraint mesh. The permeable constraint mesh is used to allow the solution in the solution tank to penetrate and contact the specimen block. The collaborative control module communicates with both the environmental simulation module and the mechanical loading module. The collaborative control module is used to acquire the environmental parameters and stress state parameters of the specimen block, and adjust the loading force output by the mechanical loading module according to the changes in the environmental parameters.

[0007] By using a permeable constraint mesh, the environmental solution in the solution tank can directly contact the specimen block; after the collaborative control module obtains the environmental parameter change data, it adjusts the loading force of the mechanical loading module to form a synchronous simulation of stress and environmental erosion.

[0008] Furthermore, the permeable restraint mesh is made of carbon fiber mesh; The molding device includes a specimen base, and the confining pressure loading component also includes a fixed side plate. The fixed side plate is fixedly connected to the upper side of the specimen base. The fixed side plate is in contact with the side of the specimen block. One end of the carbon fiber mesh is fixedly connected to the outside of the fixed side plate. The end of the carbon fiber mesh away from the fixed side plate is connected to a tensioning mechanism after wrapping around the outer circumference of the specimen block. The tensioning mechanism includes multiple independent servo tensioning devices, a left pressure plate, and a right pressure plate, which are segmented along the axial direction of the specimen block. Side holes are opened on both sides of the fixed side plate, and a central hole is opened on the outer side of the fixed side plate. After one end of the carbon fiber mesh passes through the central hole and the side hole, multiple fixed anchors are fixedly connected to the outer side of the fixed side plate. The other end of the fixed anchor is fixedly connected to the corresponding left pressure plate and right pressure plate. Screw holes are provided on the outer sides of the left and right pressure plates, and two sets of nut holes are provided on the outer side of the fixed side plate. Rotating rods are inserted into the screw holes and nut holes. Multiple independent servo tensioning devices are fixedly connected to the outer sides of the left and right pressure plates. The independent servo tensioning devices are used to adjust the tension of the carbon fiber mesh in the corresponding segment.

[0009] Furthermore, multiple miniature pressure sensors are fixedly connected to the inner side of the fixed side plate; The miniature pressure sensor communicates with the collaborative control module, which sends commands to the corresponding independent servo tensioning device to adjust the tensioning parameters based on the local force data acquired by the miniature pressure sensor. After acquiring the local force data on the specimen surface, the miniature pressure sensor, in conjunction with the axially segmented independent servo tensioning device, independently adjusts the confining pressure in different height sections of the specimen.

[0010] Furthermore, the axial loading assembly includes a fixing frame, a force-applying column, and a self-locking nut; the force-applying column is slidably connected to the top of the fixing frame, and a self-locking nut is threadedly connected to the outside of the force-applying column; The force-applying column abuts against the specimen block, and the self-locking nut is used to lock the axial position of the force-applying column.

[0011] Furthermore, the solution circulation component includes an inlet pipe, one end of which passes through the curing tank and is connected to the solution tank, and the other end of which is connected to a water pump. The input end of the water pump is connected to a first configuration tank, and the outside of the first configuration tank is connected to a water supply port. The outside of the solution tank is connected to an outlet pipe, and the other end of the outlet pipe passes through the curing tank and is connected to a second configuration tank. Water valves are fixedly connected to the outside of both the inlet pipe and the outlet pipe. The solution tank is made of transparent plexiglass, with a base plate fixedly connected to the bottom. A sample rack is fixedly connected to the upper part of the base plate, and the mold assembly is mounted on the sample rack. The solution circulation assembly, in conjunction with a water pump and a preparation tank, replaces the solution to maintain the solution state inside the tank.

[0012] Furthermore, the curing box is equipped with a sealed door, and a hinge is fixedly connected to the outside of the curing box. The sealed door is rotatably connected to the outer wall of the curing box through the hinge, and a rotating fixing button is rotatably connected above the base plate. The curing chamber is internally equipped with a temperature control component, a humidity control component, and a gas injection component. The indoor testing device also includes a photoelectric measurement module, which is fixedly connected to the outside of the solution tank. The photoelectric measurement module includes a microscopic imaging component and a laser interferometric length measuring component. The photoelectric measurement module is used to acquire surface images and deformation displacement data of the specimen block through the transparent sidewall of the solution tank, and transmit the surface images and deformation displacement data to the collaborative control module.

[0013] Furthermore, an ultrasonic oscillation generator and an adjustable speed spray head are fixedly connected to the inside of the solution tank; The collaborative control module is connected to the ultrasonic oscillation generator, which emits ultrasonic waves to the specimen block, and the adjustable speed spray head is used to spray solution onto the specimen block.

[0014] Furthermore, the collaborative control module integrates an accelerated corrosion prediction unit; The accelerated corrosion prediction unit is used to calculate the mechanical property change data of the specimen block by using the surface image obtained by the photoelectric measurement module and the stress state parameters obtained by the collaborative control module as input sequences.

[0015] Furthermore, the collaborative control module is equipped with a preset change threshold; when the solution concentration data or temperature data in the acquired environmental parameters reach the preset change threshold, the collaborative control module sends a control command to the stretching mechanism to adjust the tension of the permeable constraint net.

[0016] A second aspect of the present invention also provides a method for co-simulating the stress environment of soil and rock specimens, using the aforementioned indoor testing apparatus for co-simulating the stress environment of soil and rock specimens, comprising the following steps: S1. Place the specimen in the mold device, wrap the outer periphery of the specimen with a water-permeable constraint mesh, adjust the tension mechanism to apply the initial confining pressure, adjust the axial loading component to apply the initial axial pressure, and place the mold device into the solution tank. S2. Start the environmental simulation module to adjust the temperature, humidity and gas parameters in the curing chamber, and inject solution into the solution tank through the solution circulation component; S3. The collaborative control module acquires the environmental parameters and stress state parameters of the specimen; when the collaborative control module determines that the change of the environmental parameters meets the set conditions, it sends an instruction to the tensioning mechanism to adjust the output tension. S4. Obtain multi-field collaborative feature data of the specimen within a set test period.

[0017] This invention provides an indoor testing apparatus and method for co-simulating the stress environment of soil and rock specimens. It has the following beneficial effects: 1. This invention overcomes the structural limitations of traditional triaxial tests by using carbon fiber mesh as a permeable confining mesh and combining it with independent servo tensioning devices arranged in segments along the specimen's axial direction. While the carbon fiber mesh applies radial confining pressure to the specimen under tensile load, the micropores on its surface allow chemical solutions from the environmental simulation module to directly penetrate and contact the specimen surface. By adjusting the output tension of the independent servo tensioning devices in different segments, testers can apply refined gradient confining pressure to the specimen, thereby simulating the physical boundary of soil and rock materials under the combined action of fluid infiltration and multiaxial forces.

[0018] 2. This invention constructs a dynamic confining pressure compensation mechanism based on multi-source data fusion. It acquires local stress data of the specimen in real time through a miniature pressure sensor inside the fixed side plate, and combines it with solution concentration and temperature parameters collected by the environmental probe, which are then processed by the collaborative control module. When the specimen undergoes physical and chemical degradation due to long-term immersion in the medium, resulting in deformation-induced stress abrupt changes or when environmental parameters reach a preset threshold, the collaborative control module immediately sends adjustment commands to the corresponding independent servo tensioning device. By increasing or decreasing the mesh tension, it adaptively compensates for the confining pressure deviation, ensuring the stability of the force boundary in multi-field coupling tests over long spans.

[0019] 3. This invention is equipped with a non-contact photoelectric measurement module and an accelerated corrosion prediction unit to solve the problem that conventional contact strain gauges will fail and damage the specimen surface in corrosive liquid environments. The photoelectric measurement module continuously acquires images and displacement data of the specimen surface through the transparent plexiglass sidewall. The system splices and fuses the image features with real-time stress state parameters and inputs them into the built-in convolutional long short-term memory neural network model for calculation. Finally, it outputs the elastic modulus reduction coefficient of the soil and rock specimen in real time, thereby completing the continuous non-destructive assessment of the mechanical deterioration state of rock mass under complex geological environments. Attached Figure Description

[0020] Figure 1 This is a perspective view of the present invention; Figure 2 This is a perspective view of the curing box of the present invention; Figure 3 This is a schematic diagram of the solution tank of the present invention; Figure 4 This is a perspective view of the solution tank of the present invention; Figure 5 This is a schematic diagram of the structure of the fixing frame of the present invention; Figure 6 This is a schematic diagram of the structure of the specimen of the present invention; Figure 7 for Figure 6 A magnified view of point A; Figure 8 This is a schematic diagram of the structure of the specimen base of the present invention; Figure 9 This is a schematic diagram of the side hole structure of the present invention; Figure 10 This is a schematic diagram of the structure of the central hole in this invention; Figure 11 This is a schematic diagram of the environment simulation module of the present invention; Figure 12 This is a schematic diagram of the mechanical loading module of the present invention; Figure 13 This is a schematic diagram of data interaction in the collaborative control module of the present invention.

[0021] The components include: 1. Curing box; 2. Water pump; 3. Preparation tank one; 4. Preparation tank two; 5. Water outlet pipe; 6. Water inlet pipe; 7. Water valve; 8. Water supply port; 9. Solution tank; 10. Mold testing device; 11. Base plate; 12. Sample holder; 13. Rotary fixing button; 14. Hinge; 15. Force application column; 16. Fixing frame; 17. Self-locking nut; 18. Specimen block; 19. Specimen base; 20. Fixing side plate; 21. Left pressure plate; 22. Right pressure plate; 23. Screw hole; 24. Fixing anchor head; 25. Rotating rod; 26. Nut hole; 27. Side hole; 28. Center hole; 29. ​​Independent servo tensioning device. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Please see the appendix Figure 1 - Appendix Figure 10 This invention provides an indoor testing device for co-simulating the stress environment of soil and rock specimens. The indoor testing device includes: The environmental simulation module includes a curing chamber 1, a solution tank 9, and a solution circulation component. The solution tank 9 is connected to the outside of the solution circulation component and is fixedly connected to the inside of the curing chamber 1. The solution circulation assembly includes an inlet pipe 6, one end of which passes through the curing tank 1 and is connected to the solution tank 9. The other end of the inlet pipe 6 is connected to a water pump 2. The input end of the water pump 2 is connected to a first configuration tank 3. A water supply port 8 is connected to the outside of the first configuration tank 3. An outlet pipe 5 is connected to the outside of the solution tank 9. The other end of the outlet pipe 5 passes through the curing tank 1 and is connected to a second configuration tank 4. Water valves 7 are fixedly connected to the outside of both the inlet pipe 6 and the outlet pipe 5. The solution tank 9 is a transparent plexiglass box. A base plate 11 is fixedly connected to the bottom of the solution tank 9. A sample rack 12 is fixedly connected to the upper side of the base plate 11. The mold device 10 is set on the sample rack 12. The curing box 1 is equipped with a sealed door, and a hinge 14 is fixedly connected to the outside of the curing box 1. The sealed door is rotatably connected to the outer wall of the curing box 1 through the hinge 14. A rotary fixing button 13 is rotatably connected above the base plate 11. The curing chamber 1 is internally fixedly connected to a temperature control component, a humidity control component, and a gas injection component; An ultrasonic oscillation generator and an adjustable speed spray head are fixedly connected to the inside of the solution tank 9. Specifically, the environmental simulation module is used to construct a controlled multiphase physicochemical environment for geotechnical specimens in an indoor test environment. The specific implementation method and working mechanism of this part include the following steps and structural details.

[0024] In the construction of the environmental chamber and support system, the solution tank 9 is made of transparent organic glass to meet the light transmission requirements of the subsequent non-contact photoelectric measurement module for image acquisition. The solution tank 9 is installed in the inner cavity of the curing chamber 1 to form a double-layer nested isolation structure. To ensure the sealing of the meteorological environment inside the environmental chamber and convenient operation, the curing chamber 1 is equipped with a sealed door. A hinge 14 is fixedly connected to the outside of the curing chamber 1. The sealed door is rotatably connected to the outer wall of the curing chamber 1 through the hinge 14. In terms of the internal support structure, a base plate 11 is fixedly connected to the bottom of the solution tank 9. A rotating fixing button 13 is rotatably connected above the base plate 11 to stabilize the internal components. A sample holder 12 is fixedly connected to the upper side of the base plate 11. The mold device 10 is placed on the sample holder 12. The sample holder 12 has a water-permeable grid, which raises the mold device 10 away from the bottom of the solution tank 9 so that the solution injected into the solution tank 9 can fully contact the bottom edge of the mold device 10, aiming to provide a uniform flow field distribution around the specimen block 18.

[0025] In the external meteorological and temperature and humidity environment regulation process, the curing chamber 1 is used to control the macroscopic medium environment outside the solution tank 9. The gas injection component includes an external high-pressure gas cylinder, a pressure reducing valve, and a gas pipeline. It is used to inject a set concentration of carbon dioxide or hydrogen sulfide into the sealed cavity of the curing chamber 1 to simulate acidic underground gas conditions. The temperature regulation component includes a heating resistor and a cooling element. The humidity regulation component includes a humidification water tank and a dehumidification module. For the specific hardware circuits and closed-loop control logic of the temperature regulation component and the humidity regulation component, those skilled in the art can use a conventional proportional-integral-derivative temperature and humidity controller, which is a well-known technology in the field and will not be described in detail here.

[0026] In the dynamic circulation and media renewal control design of the solution, the solution circulation component is used to maintain the effective concentration of the chemical medium in the solution tank 9. During the test, the set solute and solvent are added to the configuration tank 3 through the water supply port 8. The water valve 7 on the outside of the water inlet pipe 6 and the water outlet pipe 5 is opened. The water pump 2 steadily pumps the solution in the configuration tank 3 into the solution tank 9. The reaction waste liquid after chemical corrosion with the specimen block 18 is discharged into the configuration tank 4 through the water outlet pipe 5. In this embodiment, this dynamic circulation mechanism reduces the polarization phenomenon of ion concentration on the surface of the specimen block 18 in the conventional static immersion test.

[0027] During the solution circulation and renewal phase described above, the physical evolution of the solution concentration in solution tank 9 with the flow rate of water pump 2 and circulation time is controlled and calculated based on the material conservation formula, specifically expressed as follows: ; In the formula; express The actual concentration of the solution in solution tank 9 at any given time. This indicates the initial concentration of the formulation continuously injected into configuration pool 3. This indicates the initial concentration in solution tank 9. The base constant of the natural logarithm, This indicates the volumetric flow rate of the solution driven by pump 2. This indicates the effective volume of the solution in solution tank 9. This indicates the duration of the circulating flow. From a general perspective, the above formula describes the physical process where, with the continuous injection of fresh solution, the mixed concentration within the environmental chamber exponentially approaches the concentration of the injected source. During this process, researchers can flexibly control the rate of deterioration of the corrosive environment by adjusting the flow rate parameters. As a preferred method, to ensure the stability of concentration adjustment, the effective volume... The volume of the test mold device 10 is typically selected to be five to ten times that of the water pump 2, while the volumetric flow rate of the water pump 2 is... Based on the expected update cycle, the ratio is set so that The flow rate is controlled within the range of 0.1 to 0.5 per hour to avoid unnatural hydrodynamic damage to the specimen block 18 caused by high flow rate.

[0028] In the application of dynamic environmental excitation, the ultrasonic oscillation generator and the adjustable speed spray head are used to provide hydrodynamic and acoustic dynamic loads to the specimen. The adjustable speed spray head is installed on the top inside the solution tank 9. Its interior includes a flow regulating valve and a wide-angle atomizing nozzle, which is used to spray circulating solution onto the surface of the specimen from top to bottom to simulate the scouring and erosion process of rainfall infiltration or groundwater fissure flow. At the same time, the ultrasonic oscillation generator is fixed to the inner wall of the solution tank 9. The high-frequency mechanical waves generated when it is started induce acoustic cavitation effect in the solution medium. The micro-jet generated by the collapse of cavitation bubbles promotes the penetration of chemical solution into the original micro-cracks of the specimen, which helps to advance the dissolution evolution process under indoor test conditions.

[0029] See appendix Figure 1 - Appendix Figure 10 The mechanical loading module is set inside the solution tank 9. The mechanical loading module includes a mold device 10, which is used to accommodate the specimen block 18. The mold device 10 includes an axial loading component and a confining pressure loading component. The confining pressure loading component includes a permeable restraint mesh and a tensioning mechanism. The tensioning mechanism is connected to the outside of the permeable restraint mesh. The permeable restraint mesh is used to allow the solution in the solution tank 9 to penetrate and contact the specimen block 18. The permeable restraint mesh is made of carbon fiber mesh. The molding device 10 includes a specimen base 19, and the confining pressure loading component also includes a fixed side plate 20. The fixed side plate 20 is fixedly connected to the upper side of the specimen base 19. The fixed side plate 20 fits against the side of the specimen block 18. One end of the carbon fiber mesh is fixedly connected to the outside of the fixed side plate 20. The end of the carbon fiber mesh away from the fixed side plate 20 is connected to a tensioning mechanism after wrapping around the outer periphery of the specimen block 18. The tensioning mechanism includes multiple independent servo tensioning devices 29, a left pressure plate 21, and a right pressure plate 22, which are segmented along the axial direction of the specimen block 18. Side holes 27 are provided on both sides of the fixed side plate 20, and a central hole 28 is provided on the outer side of the fixed side plate 20. After one end of the carbon fiber mesh passes through the central hole 28 and the side hole 27, multiple fixed anchors 24 are fixedly connected to the outer side of the fixed side plate 20. The other end of the fixed anchor 24 is fixedly connected to the corresponding left pressure plate 21 and right pressure plate 22. Screw holes 23 are respectively opened on the outer side of the left pressure plate 21 and the right pressure plate 22. Two sets of nut holes 26 are opened on the outer side of the fixed side plate 20. Rotating rods 25 are inserted into the screw holes 23 and the nut holes 26. Multiple independent servo tensioning devices 29 are respectively fixedly connected to the outer side of the left pressure plate 21 and the right pressure plate 22. The independent servo tensioning devices 29 are used to adjust the tension of the carbon fiber mesh in the corresponding segment. The axial loading assembly includes a fixed frame 16, a force-applying column 15, and a self-locking nut 17; the force-applying column 15 is slidably connected to the top of the fixed frame 16, and the self-locking nut 17 is threadedly connected to the outside of the force-applying column 15. The force-applying column 15 abuts against the specimen block 18, and the self-locking nut 17 is used to lock the axial position of the force-applying column 15. Specifically, the mechanical loading module is used to apply and maintain a set multiaxial stress state on soil and rock specimens in a solution environment to simulate the actual geostress boundary conditions in deep strata. The specific structural assembly and force conversion process of this module includes the following operational steps. During the construction of specimen positioning and axial constant deformation constraints, the specimen base 19 of the test mold device 10 provides a bottom support platform for the specimen block 18. The fixing frame 16 is straddling and installed above the specimen base 19 and forms a force reaction frame. The tester presses down on the force-applying column 15, which is slidably connected to the top of the fixing frame 16, so that the bottom end of the force-applying column 15 abuts against the top surface of the specimen block 18, thereby applying an initial vertical compressive load downward. After reaching the expected axial stress, the self-locking nut 17 connected to the outer thread of the force-applying column 15 is rotated to tighten it and abut against the fixing frame 16 to lock the axial position of the force-applying column 15. In this embodiment, the axial loading component constitutes a rigid limiting boundary for the axial displacement of the specimen block 18, which can simulate the physical state of the soil and rock mass under the heavy pressure of the overlying rock layer in the deep strata and which cannot expand freely axially.

[0030] After completing the axial constraint, the assembly transitions to the flexible, permeable lateral confining pressure loading boundary. Conventional triaxial tests often use a sealed rubber sleeve to wrap the specimen block 18, thus blocking the direct intrusion of external fluid media. To overcome this physical isolation limitation, the confining pressure loading component in this design uses carbon fiber mesh as a permeable constraint mesh. The carbon fiber mesh not only possesses the mechanical properties to withstand high tensile loads, but its surface is also uniformly distributed with micropores. This permeable constraint mesh allows the chemical solution in the solution tank 9 to directly permeate and interact with the side of the specimen block 18. When the surfaces come into contact, the inner arc surface of the fixed side plate 20, which is fixedly connected to the upper side of the specimen base 19 in the structural assembly, fits against a part of the side surface of the specimen block 18. Side holes 27 are opened on both sides of the fixed side plate 20, and a central hole 28 is opened on the outer side of the fixed side plate 20. One end of the carbon fiber mesh passes through the central hole 28 and the side hole 27 and is firmly fixed to the outer side of the fixed side plate 20. The other end serves as a movable end, closely adhering to the outer periphery of the specimen block 18 and going around once before connecting to the lateral tensioning mechanism, thus forming an encircling open lateral constraint enclosure.

[0031] To achieve precise adjustment of radial stress and enter the servo application and stress conversion control steps of gradient confining pressure, the tensioning mechanism includes multiple independent servo tensioning devices 29 arranged in segments at different heights along the axial direction of the specimen block 18. The corresponding carbon fiber mesh is also divided into multiple independent stress-bearing segments. The left pressure plate 21 and right pressure plate 22 on the movable end side are responsible for clamping the edge of the carbon fiber mesh. The push-pull execution ends of the independent servo tensioning devices 29 are fixedly connected to the outer sides of the left pressure plate 21 and right pressure plate 22, respectively. When the independent servo tensioning device 29 retracts and pulls outward, the carbon fiber mesh tightens accordingly, generating inward radial compressive stress on the side of the specimen block 18 by relying on the circumferential tension force. By adjusting the output force of the independent servo tensioning devices 29 in different segments, gradient confining pressure control at different depths along the axial direction of the specimen block 18 can be achieved. For the bottom motor drive and force closed-loop control strategy of the independent servo tensioning device 29, those skilled in the art can use a conventional servo motor driver in conjunction with the actuator cylinder to achieve this, which is a well-known technology in the field and will not be described in detail here.

[0032] In the aforementioned confining pressure loading process, the conversion relationship between the linear tensile force output by the independent servo tensile device 29 and the equivalent radial confining pressure actually borne by the surface of the specimen block 18 is calculated based on a thin-walled circular ring force model including friction attenuation correction. The specific mechanical equilibrium formula is expressed as follows: ; In the formula; This indicates the actual effective radial confining pressure exerted on the side of specimen block 18 within the corresponding segment. This represents the end linear tensile force applied by a single independent servo tensioning device 29 to the corresponding segment of carbon fiber mesh. This indicates the cross-sectional diameter of specimen block 18 under compression. This indicates the axial width distribution dimension of the carbon fiber mesh corresponding to this segment. The base constant of the natural logarithm, This represents the coefficient of sliding friction between the carbon fiber mesh and the rough surface of specimen block 18. This indicates the actual center wrap angle of the carbon fiber mesh-covered specimen block 18, and is typically taken as a value. Within the arc; from the general perspective of the principle, the formula reveals the mapping mechanism of the end tension to the radial pressure of the inner cylinder under the condition of flexible belt circling force. At the same time, it considers the stress attenuation effect along the path caused by the frictional resistance between the mesh and the rock mass contact surface. Based on this mechanical conversion relationship, the control system can reverse solve the basic tension command required by each independent servo tensioning device 29 through the set target confining pressure value. As a preferred method, the upper limit of the tension parameter setting is limited by the ultimate tensile strength of the carbon fiber mesh. During the test, it is usually controlled within 60% of the ultimate tensile strength to leave a safety margin. The friction coefficient needs to be obtained by sliding friction calibration test in advance according to the roughness of the surface of the specimen block 18, and its value range is generally between 0.1 and 0.4, so as to ensure that the mesh still has accurate stress compensation ability when the specimen block 18 undergoes nonlinear deformation.

[0033] See appendix Figure 11 - Appendix Figure 13 The collaborative control module is connected to the environmental simulation module and the mechanical loading module respectively. The collaborative control module is used to obtain the environmental parameters and stress state parameters of the specimen block 18, and adjust the loading force output by the mechanical loading module according to the change data of the environmental parameters. Multiple miniature pressure sensors are fixedly connected to the inner side of the fixed side plate 20; The miniature pressure sensor is connected to the collaborative control module. The collaborative control module is used to send instructions to the corresponding independent servo tensioning device 29 to adjust the tensioning parameters based on the local force data obtained by the miniature pressure sensor. The indoor testing device also includes a photoelectric measurement module, which is fixedly connected to the outside of the solution tank 9. The photoelectric measurement module includes a microscopic imaging component and a laser interferometric length measuring component. The photoelectric measurement module is used to obtain the surface image and deformation displacement data of the specimen block 18 through the transparent side wall of the solution tank 9, and transmit the surface image and deformation displacement data to the collaborative control module. An ultrasonic oscillation generator and an adjustable speed spray head are fixedly connected to the inside of the solution tank 9. The collaborative control module is connected to the ultrasonic oscillation generator, which is used to emit ultrasonic waves to the specimen block 18, and the adjustable speed spray head is used to spray solution onto the specimen block 18. The collaborative control module integrates an accelerated corrosion prediction unit. The accelerated corrosion prediction unit is used to perform calculations using the surface image obtained by the photoelectric measurement module and the stress state parameters obtained by the collaborative control module as input sequences, and outputs the mechanical property change data of the specimen block 18. The collaborative control module is equipped with a preset change threshold. When the solution concentration data or temperature data in the acquired environmental parameters reach the preset change threshold, the collaborative control module sends a control command to the stretching mechanism to adjust the tension of the permeable constraint net. Specifically, the collaborative control module acts as the data processing center and action execution core of the entire indoor testing device to achieve multi-source information interaction and dynamic closed-loop mechanical boundary. The specific working logic and collaborative control method of this module include the following implementation steps. In the data perception and information acquisition network construction stage, the collaborative control module communicates with the environmental simulation module and the mechanical loading module to build a data interaction system covering the entire test process. Multiple miniature pressure sensors are fixedly connected to the inner side of the fixed side plate 20 inside the test mold device 10. These miniature pressure sensors are in real time attached to the side of the soil and rock specimen block 18 to capture the local stress changes generated when it absorbs water and expands or is softened by chemical media corrosion. The relevant sensing nodes communicate with the collaborative control module to transmit continuous local stress data back to the control center. At the same time, the collaborative control module synchronously acquires the macroscopic environmental parameters of the specimen block 18 through various environmental probes. These environmental parameters specifically include the solution concentration data and temperature data of the current immersion medium, thereby forming a comprehensive set of stress state parameters including physicochemical variables and internal mechanical responses to provide basic data support for subsequent dynamic servo control.

[0034] As the experiment progresses through prolonged immersion in the medium and under stress, it enters the stage of dynamic compensation servo control based on threshold judgment for confining pressure. The physicochemical degradation of specimen block 18 caused by environmental factors directly disrupts the original stress equilibrium state. To correct the mechanical boundary conditions in real time, the collaborative control module is pre-configured with preset variation thresholds. These thresholds cover the allowable variation difference in solution concentration and the limit for local stress surges. As a preferred approach, the preset variation threshold for solution concentration data is typically set to 5% to 10% of the initial prepared concentration, while the limit for local stress surges is set to 2% to 5% of the initial applied confining pressure. The collaborative control module... When the solution concentration data or temperature data in the acquired environmental parameters reach the preset change threshold, or when the change in local force data acquired based on the micro pressure sensor exceeds the above limit, a dynamic adjustment command is generated and sent to the tensioning mechanism to adjust the tension of the permeable constraint mesh. Specifically, the collaborative control module sends a command to the corresponding independent servo tensioning device 29 to adjust the tensioning parameters, guiding the independent servo tensioning device 29 to compensate for the confining pressure loss of the specimen block 18 caused by corrosion shrinkage or water absorption expansion by increasing or decreasing the output tension, so that the loading force output by the mechanical loading module can adaptively follow the volume deformation of the specimen block 18 caused by environmental evolution.

[0035] Simple contact-based mechanical sensing has certain observational limitations. Therefore, a non-contact optical monitoring and environmental excitation collaborative intervention mechanism is configured for this system. Considering that conventional internal strain gauges will fail in corrosive solutions and that the application process will damage the surface integrity of the specimen block 18, the indoor testing device is equipped with a photoelectric measurement module fixedly connected to the outside of the solution tank 9. This photoelectric measurement module mainly includes a microscopic imaging component and a laser interferometry component, used to non-destructively acquire surface images and deformation displacement data of the specimen block 18 exposed in the solution through the transparent plexiglass sidewall of the solution tank 9. The acquired surface images and deformation data are then transmitted to the outside of the solution tank. Displacement data is synchronously transmitted to the collaborative control module for fusion analysis. During this monitoring cycle, the collaborative control module maintains a communication connection with the ultrasonic oscillation generator fixedly connected inside the solution tank 9. By sending an excitation signal of a specific frequency, the ultrasonic oscillation generator is controlled to emit ultrasonic waves to the specimen block 18, thereby using the cavitation effect to overcome the capillary resistance of the fluid and drive the medium to penetrate into the micro-fractures of the rock and soil. At the same time, the system synchronously controls the adjustable speed spray head to spray solution onto the surface of the specimen block 18 to simulate the dynamic scouring of fracture water. The above-mentioned opto-mechanical-electro-acoustic collaborative operation mechanism effectively realizes the cross-field coupling simulation of mechanical load and hydro-meteorological dynamic load.

[0036] To extract material degradation patterns from massive amounts of multi-field data, the system performs macro- and micro-data fusion and accelerated corrosion prediction model construction steps. The collaborative control module integrates an accelerated corrosion prediction unit to assess the damage process of specimen block 18. This unit uses the surface image acquired by the photoelectric measurement module and the stress state parameters acquired by the collaborative control module as input sequences to perform forward propagation calculations and output the current mechanical property changes of specimen block 18. In this embodiment, the accelerated corrosion prediction unit incorporates a multi-modal fusion convolutional long short-term memory neural network model. In data preprocessing and structural connection logic, the system crops and scales the acquired surface image to... After specifying the resolution, the data is input into a convolutional neural network layer for feature extraction. Through multi-layer convolution and pooling operations, the microcrack morphology features are extracted and flattened into a one-dimensional image feature vector. Subsequently, this one-dimensional image feature vector is concatenated and fused with the normalized one-dimensional stress state parameters in the channel dimension to avoid algorithm dead zones caused by tensor dimension mismatch. The concatenated comprehensive feature sequence is fed into a long short-term memory network layer to extract the damage accumulation dependency in the time dimension. Finally, it is processed through a fully connected layer for numerical regression output. The specific physical state corresponding to this output result is the current elastic modulus reduction coefficient of the soil and rock specimen block 18, thereby intuitively quantifying the degree of mechanical degradation of the material.

[0037] To ensure the accuracy of the prediction model's output, it is essential to optimize the model parameters and perform closed-loop training and updates. Before the formal start of the experiment, the testers used historical data to conduct offline training and optimization of the convolutional long short-term memory neural network model. The training samples came from a multi-field coupled test dataset accumulated in the laboratory for the same batch of geotechnical materials under standard immersion and destructive stress conditions. The sample labels were strictly defined as the actual elastic modulus reduction values ​​measured through destructive mechanics tests. The training steps included inputting preprocessed historical time-series samples into the network architecture for inference calculation according to batch size, comparing the error between the network's predicted values ​​and the true label values, and using the backpropagation algorithm combined with an optimizer to update the weights and bias parameters of the network layer by layer according to the set learning rate. The objective function for model iterative optimization was designed based on the mean square error calculation rules, and the specific loss function calculation formula is expressed as follows: ; In the formula; This represents the mean squared error loss value calculated by the network in a single iteration batch. This indicates the total number of samples in this batch currently being sent for network training. This is the sequence number variable of the training samples within a single iteration batch. This indicates that the accelerated corrosion prediction unit is for the first The predicted value of the elastic modulus reduction factor output from the forward calculation of historical samples. Indicates the first The true label value of the elastic modulus reduction coefficient corresponding to each historical sample, based on physical test calibration, can be implemented by those skilled in the art using conventional open-source deep learning frameworks. This is a well-known technology in the field and will not be elaborated here.

[0038] The method for co-simulating the stress environment of soil and rock specimens described below can be referred to in correspondence with the indoor test device for co-simulating the stress environment of soil and rock specimens described above. This invention also provides a method for collaborative simulation of the stress environment of soil and rock specimens, comprising the following steps: S1. Place the specimen block 18 in the mold-making device 10, wrap the outer periphery of the specimen block 18 with the water-permeable constraint mesh, adjust the tension mechanism to apply the initial confining pressure, adjust the axial loading component to apply the initial axial pressure, and place the mold-making device 10 into the solution tank 9. S2. Start the environmental simulation module to adjust the temperature, humidity and gas parameters in the curing chamber 1, and inject solution into the solution tank 9 through the solution circulation component; S3. The collaborative control module acquires the environmental parameters and stress state parameters of the specimen block 18. When the collaborative control module determines that the change in environmental parameters meets the set conditions, it sends an instruction to the tensioning mechanism to adjust the output tension. S4. Obtain multi-field collaborative feature data of specimen block 18 within the set test period; The method in this embodiment can be used to execute the above system embodiment, and its principle and technical effect are similar, so they will not be described again here; Working principle: First, the sealed door on the curing chamber 1 is opened by rotating the hinge 14. The base plate 11 is stabilized by operating the rotating fixing button 13. The specimen block 18 is placed on the test mold device 10 on the sample rack 12 inside the solution tank 9. The side of the specimen block 18 is wrapped with a water-permeable constraint mesh. During operation, one end of the water-permeable constraint mesh is passed through the central hole 28 and the side hole 27 of the fixing side plate 20 for secure fixation. The other end is wrapped around the outer circumference of the specimen block 18 and then clamped by the clamping component. Then, the sealed door is closed, and the temperature regulation component, humidity regulation component and gas injection component inside the curing chamber 1 are turned on to establish temperature, humidity and gas boundary conditions. The water valve 7 is opened and the water pump 2 is started. The water pump 2 pumps the solution in the first preparation tank 3 into the solution tank 9 through the inlet pipe 6 at the set volume flow rate. The reaction waste liquid is discharged into the second preparation tank 4 through the outlet pipe 5. The chemical medium concentration in the solution tank 9 is maintained through circulation operation to provide the set corrosion environment for the specimen block 18. Next, the downward-pressing force column 15 is brought into contact with the top of the specimen block 18, and the self-locking nut 17 is tightened to press against the fixing frame 16 to lock the axial position of the force column 15, thus forming an axial deformation constraint on the specimen block 18. The collaborative control module controls the independent servo tensioning device 29, which is arranged in segments along the axial direction of the specimen block 18, to retract outward according to the confining pressure setting value. The independent servo tensioning device 29 drives the left pressure plate 21 and the right pressure plate 22 to be guided by the rotating rod 25 passing through the screw hole 23 and the nut hole 26, and supported and restricted by the fixed anchor head 24, to smoothly stretch the permeable constraint mesh. The permeable constraint mesh tightens to generate circumferential tension and applies radial confining pressure to the side of the specimen block 18. The ultrasonic oscillation generator and the adjustable speed spray head inside the solution tank 9 are activated. The acoustic cavitation effect generated by the ultrasonic oscillation generator causes the solution to penetrate into the internal micro-cracks of the specimen block 18, and the adjustable speed spray head sprays the solution onto the surface of the specimen block 18 to generate water scouring. During the test run, the miniature pressure sensor inside the fixed side plate 20 collects stress data generated by the local deformation of the specimen block 18. The photoelectric measurement module obtains the surface image and deformation displacement data of the specimen block 18 through the transparent side wall of the solution tank 9. The collaborative control module summarizes the mechanical data and solution concentration and temperature parameters. When it is determined that the solution concentration or temperature data reaches the preset change threshold, or the change amplitude of the local stress data exceeds the limit, the collaborative control module sends a command to the corresponding independent servo tensioning device 29 to adjust the tension of the permeable constraint net to compensate for the confining pressure deviation caused by the deformation of the specimen block 18. At the same time, the accelerated corrosion prediction unit inside the collaborative control module splices and fuses the extracted surface image features with the stress state parameters, calculates them through the built-in convolutional long short-term memory neural network model, and outputs the current elastic modulus reduction coefficient of the specimen block 18 to complete the assessment of the mechanical deterioration state of the soil and rock materials.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An indoor testing device for co-simulating the stress environment of soil and rock specimens, characterized in that, The indoor testing apparatus includes: The environmental simulation module includes a curing box (1), a solution tank (9) and a solution circulation component. The solution tank (9) is connected to the outside of the solution circulation component and is fixedly connected to the inside of the curing box (1). A mechanical loading module is disposed in the solution tank (9). The mechanical loading module includes a mold device (10) for accommodating a specimen block (18). The mold device (10) includes an axial loading component and a confining pressure loading component. The confining pressure loading component includes a permeable constraint mesh and a tensioning mechanism. The tensioning mechanism is connected to the outside of the permeable constraint mesh. The permeable constraint mesh is used to allow the solution in the solution tank (9) to penetrate and contact the specimen block (18). The collaborative control module is connected to the environmental simulation module and the mechanical loading module respectively. The collaborative control module is used to obtain the environmental parameters and stress state parameters of the specimen block (18), and adjust the loading force output by the mechanical loading module according to the change data of the environmental parameters.

2. The indoor testing device for co-simulating the stress environment of soil and rock specimens according to claim 1, characterized in that: The permeable restraint mesh is a carbon fiber mesh. The mold-making device (10) includes a specimen base (19), and the confining pressure loading assembly also includes a fixed side plate (20). The fixed side plate (20) is fixedly connected to the upper side of the specimen base (19). The fixed side plate (20) fits against the side of the specimen block (18). One end of the carbon fiber mesh is fixedly connected to the outside of the fixed side plate (20). The end of the carbon fiber mesh away from the fixed side plate (20) is connected to the tensioning mechanism after wrapping around the outer periphery of the specimen block (18). The stretching mechanism includes multiple independent servo stretching devices (29) segmented along the axial direction of the specimen block (18), a left pressure plate (21) and a right pressure plate (22). Side holes (27) are provided on both sides of the fixed side plate (20), and a central hole (28) is provided on the outer side of the fixed side plate (20). After one end of the carbon fiber mesh passes through the central hole (28) and the side hole (27), multiple fixed anchors (24) are fixedly connected to the outer side of the fixed side plate (20). The other end of the fixed anchor (24) is fixedly connected to the corresponding left pressure plate (21) and right pressure plate (22). The left pressure plate (21) and the right pressure plate (22) are respectively provided with screw holes (23), and the fixed side plate (20) is provided with two sets of nut holes (26). Rotating rods (25) are inserted into the screw holes (23) and the nut holes (26). Multiple independent servo tensioning devices (29) are respectively fixedly connected to the outside of the left pressure plate (21) and the right pressure plate (22). The independent servo tensioning devices (29) are used to adjust the tension of the carbon fiber mesh in the corresponding segment.

3. The indoor testing device for co-simulating the stress environment of soil and rock specimens according to claim 2, characterized in that: Multiple miniature pressure sensors are fixedly connected to the inner side of the fixed side plate (20); The miniature pressure sensor is communicatively connected to the collaborative control module. The collaborative control module is used to send instructions to adjust the tension parameters to the corresponding independent servo tensioning device (29) based on the local force data obtained by the miniature pressure sensor.

4. The indoor testing device for co-simulating the stress environment of soil and rock specimens according to claim 1, characterized in that: The axial loading assembly includes a fixing frame (16), a force-applying column (15), and a self-locking nut (17); the top of the fixing frame (16) is slidably connected to the force-applying column (15), and the outside of the force-applying column (15) is threadedly connected to the self-locking nut (17). The force-applying column (15) abuts against the test piece block (18), and the self-locking nut (17) is used to lock the axial position of the force-applying column (15).

5. The indoor testing device for co-simulating the stress environment of soil and rock specimens according to claim 1, characterized in that: The solution circulation assembly includes an inlet pipe (6), one end of which passes through the curing tank (1) and is connected to the solution tank (9). The other end of the inlet pipe (6) is connected to a water pump (2). The input end of the water pump (2) is connected to a first configuration tank (3). The outside of the first configuration tank (3) is connected to a water supply port (8). The outside of the solution tank (9) is connected to an outlet pipe (5). The other end of the outlet pipe (5) passes through the curing tank (1) and is connected to a second configuration tank (4). Water valves (7) are fixedly connected to the outside of both the inlet pipe (6) and the outlet pipe (5). The solution tank (9) is a transparent organic glass box. A base plate (11) is fixedly connected to the bottom of the solution tank (9). A sample rack (12) is fixedly connected to the upper side of the base plate (11). The test mold device (10) is set on the sample rack (12).

6. The indoor testing device for co-simulating the stress environment of soil and rock specimens according to claim 5, characterized in that: The maintenance box (1) is provided with a sealed door, and a hinge (14) is fixedly connected to the outside of the maintenance box (1). The sealed door is rotatably connected to the outer wall of the maintenance box (1) through the hinge (14). A rotating fixing button (13) is rotatably connected above the base plate (11). The curing box (1) is internally fixedly connected to a temperature regulation component, a humidity regulation component, and a gas injection component; The indoor testing device also includes a photoelectric measurement module, which is fixedly connected to the outside of the solution tank (9). The photoelectric measurement module includes a microscopic imaging component and a laser interferometric length measuring component. The photoelectric measurement module is used to obtain the surface image and deformation displacement data of the specimen block (18) through the transparent sidewall of the solution tank (9), and transmit the surface image and deformation displacement data to the collaborative control module.

7. The indoor testing device for co-simulating the stress environment of soil and rock specimens according to claim 5, characterized in that: An ultrasonic oscillation generator and an adjustable speed spray head are fixedly connected to the inside of the solution tank (9); The collaborative control module is communicatively connected to the ultrasonic oscillation generator, which is used to emit ultrasonic waves to the test piece block (18), and the adjustable speed spray head is used to spray the solution onto the test piece block (18).

8. The indoor testing device for co-simulating the stress environment of soil and rock specimens according to claim 6, characterized in that: The collaborative control module integrates an accelerated corrosion prediction unit. The accelerated corrosion prediction unit is used to calculate the mechanical property change data of the specimen block (18) by using the surface image obtained by the photoelectric measurement module and the stress state parameters obtained by the collaborative control module as input sequences.

9. An indoor testing apparatus for co-simulating the stress environment of soil and rock specimens according to any one of claims 1 to 8, characterized in that: The collaborative control module is configured with a preset variation threshold; the collaborative control module is used to send a control command to the stretching mechanism to adjust the tension of the permeable constraint net when it determines that the solution concentration data or temperature data in the acquired environmental parameters reach the preset variation threshold.

10. A method for collaborative simulation of the stress environment of soil and rock specimens, characterized in that, The indoor testing apparatus for co-simulating the stress environment of geotechnical specimens as described in any one of claims 1 to 9 includes the following steps: S1. Place the specimen block (18) in the mold test device (10), wrap the outer periphery of the specimen block (18) with the water-permeable constraint mesh, adjust the tensioning mechanism to apply the initial confining pressure, adjust the axial loading component to apply the initial axial pressure, and place the mold test device (10) into the solution tank (9). S2. Start the environmental simulation module to adjust the temperature, humidity and gas parameters in the curing box (1), and inject solution into the solution box (9) through the solution circulation component; S3. The collaborative control module obtains the environmental parameters and stress state parameters of the specimen block (18); when the collaborative control module determines that the change of the environmental parameters meets the set conditions, it sends an instruction to the tensioning mechanism to adjust the output tension. S4. Obtain multi-field collaborative feature data of the specimen block (18) within the set test period.

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