Multifunctional rock-soil mechanical testing system for controlling temperature, humidity and salinity in extreme environment

Abstract

The invention discloses a multifunctional geotechnical mechanical testing system for controlling temperature, humidity and salinity in an extreme environment, and relates to the technical field of ocean geotechnical engineering and geotechnical engineering. The system integrates a high-precision temperature and humidity and salinity control system, can accurately simulate the influence of complex environments such as extreme temperature and humidity, salt spray corrosion and the like on the mechanical properties of geotechnical materials, supports a direct shear test, a pull-out test, a soil body single-particle crushing test and a geosynthetic material stretching and puncturing test, can distinguish static, dynamic and long-term creep test modes, and can be used for testing the mechanical properties of the geotechnical materials. Comprising creep mechanical property testing under cyclic direct shear and continuous load. A visual monitoring assembly is additionally arranged, so that the microscopic deformation and damage process of the sample can be recorded in real time. Through multifunctional integration, temperature, humidity and salinity joint control, visual monitoring and dynamic and static coupling test devices, the technical bottlenecks of single function, environment simulation limitation and microcosmic observation deficiency of traditional equipment are solved, and high engineering application value and popularization potential are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a multifunctional geotechnical mechanics test system for temperature, humidity and salinity control in extreme environments, belonging to the field of marine geotechnical engineering and geotechnical engineering test technology. BACKGROUND

[0002] In (marine) geotechnical engineering, the failure mechanism of geotechnical materials and the interface between soil and structure is essentially the result of long-term stress accumulation and complex environmental (temperature, humidity, salt corrosion) coupling. It presents significant particularity in scenes such as coastal saline soil and island reef foundation. The interface stability is restricted by temperature effect, humidity change, salt mist corrosion and creep behavior: on the one hand, seasonal temperature difference, tidal humidity fluctuation and salt erosion will change the physical and mechanical properties of soil and structure (such as geosynthetic materials), leading to the decay of interface strength; on the other hand, the creep deformation of the interface under long-term shear stress will continue to accumulate, which is particularly prominent in marine engineering such as reinforced soil retaining wall and submarine pipeline foundation, which relies on the reinforcement effect of geosynthetic materials. With the frequent occurrence of extreme weather events, the temperature, humidity and even salinity of the environment of soil, structure and geosynthetic materials are showing dramatic fluctuations. Such multi-parameter coupling has an undeniable impact on their mechanical properties and interface behavior. Therefore, it is urgent to carry out systematic research on soil strength, soil-structure interface mechanical properties and geosynthetic material mechanical properties under different temperature, humidity and salinity conditions. However, the existing test equipment has obvious limitations: in terms of environmental simulation, the temperature and humidity control accuracy is insufficient or the adjustment range is narrow (mostly limited to normal temperature or small amplitude fluctuation range), it is difficult to reproduce extreme low temperature, high temperature, high humidity and other complex scenes, and more commonly lack of salt mist corrosion and other salinity environment simulation capability, which cannot reveal the degradation mechanism of salt erosion on material interface in scenes such as coastal saline soil and island reef foundation; in terms of functional integration, traditional equipment is mostly designed for single test type (such as direct shear apparatus only for shear test, and pull-out apparatus only for interface pull-out test), which needs to be equipped with multiple separate equipment for direct shear, pull-out, creep, crushing and piercing tests, not only occupying a large amount of laboratory space, increasing the purchase and maintenance cost, but also reducing the comparability of test data due to equipment differences, and the operation process is complicated and inefficient.

[0003] The existing research on test instruments for measuring the effect of temperature and humidity on the mechanical properties of soil and structure interface is as follows: Patent application number CN201711370202.5: only controls temperature through a constant temperature water bath circulation system, without humidity and salinity control function; only supports sand direct shear test, cannot test soil and structure interface mechanical properties; does not have multi-functional integration capability such as pull-out, piercing and crushing, and does not have visual monitoring function.

[0004] Patent application number CN201811310485.9: missing temperature, humidity, and salinity control module, limited to normal temperature environment testing; although it supports direct shear and pullout test integration and dynamic load application, the data monitoring does not integrate environmental parameters, and the influence of the environment on the mechanical properties cannot be analyzed; no visualization function.

[0005] Patent application CN202310289793.2: only integrates high and low temperature systems (-20℃ to 50℃), without humidity, salinity control, and temperature and humidity coupling simulation capabilities; the function is limited to direct shear and pullout tests, lacks piercing, crushing, and other modules, and does not use standardized accessories for quick switching; no visualization monitoring function.

[0006] Patent application number CN202121477710.5: no temperature, humidity, or salinity control function, limited to normal temperature testing; only supports direct shear and pullout, without multi-functional expansion capabilities; no mention of large-scale sample adaptability, and no visualization function.

[0007] Patent application number CN201910407217.7: although it can perform creep tests, it does not consider the influence of temperature, humidity, and salinity on the mechanical properties of the sample, and does not have related environmental control modules; the function is single and only suitable for vertical direct shear creep; no visualization function.

[0008] Patent publication number CN118424908 A: no temperature, humidity, or salinity control, unable to simulate extreme environments such as freezing and thawing, high temperature, etc.; only targets internal shear of soil samples, without a dedicated test module for the interface between soil and structures; no visualization monitoring function.

[0009] Patent publication number CN221631205U: no temperature, humidity, or salinity control module, without integrated environmental simulation function; only targets rock sample shear, without soil and structure interface test function, and no sensor or observation interface reserved; no visualization function.

[0010] Patent application number CN200910200536.7: no wide-range temperature control capability, no humidity or salinity control function, unable to meet the testing needs in extreme environments such as low temperature and high temperature; although it supports soil synthesis material related direct shear tests, the function is single and has no visualization monitoring function.

[0011] In summary, existing patents generally have problems such as missing environmental control dimensions (no humidity, salinity control, limited temperature control range), low functional integration (only supporting single or a few test types), and lack of visualization monitoring capabilities, making it difficult to meet the research needs of multi-dimensional mechanical properties of geotechnical materials in complex environments.

[0012] To this end, the application precisely reproduces extreme and complex environmental conditions by integrating a wide-range temperature and humidity (-50℃~200℃, 10%RH~95%RH) and salinity (0-40%) combined control system; at the same time, modular standardization design is adopted to realize rapid switching of multiple test functions such as direct shear, drawing, creep, crushing, stretching, and piercing. SUMMARY

[0013] The application is aimed at the deficiencies in the prior art, and proposes a multifunctional tester integrating direct shear, drawing, creep, soil single particle crushing, and geosynthetic material stretching and piercing tests, and having large-scale sample capacity, precise temperature and humidity salinity control, and visual monitoring function. The core purpose is to solve the problems of single function of traditional equipment, inability to simulate complex marine environments (temperature and humidity, salinity), limited sample size, lack of microscopic observation means, and inability to perform long-term creep tests.

[0014] The object of the application can be achieved by the following technical solutions.

[0015] A multifunctional geotechnical mechanics test system for temperature and humidity salinity control in extreme environments, the system comprising a horizontal force loading mechanism, a vertical loading device (including a geosynthetic material piercing device), a temperature and humidity salinity control system, a modular test assembly (including a shear box, a drawing test box, and a geosynthetic material clamp), a visual monitoring assembly, and a data acquisition system.

[0016] The horizontal force loading mechanism is linked to a horizontal push-pull rod through a threaded column and a sensor, and is driven by a motor to realize accurate control of load and displacement; the vertical loading device adopts a hydraulic servo system and can apply a maximum normal stress of 1000kPa.

[0017] The temperature and humidity salinity control system integrates an environmental temperature and humidity salinity box, adjusts the temperature and humidity in the box through a PID algorithm, adjusts the salinity through automatic proportioning of salt solution and atomizing nozzles, and has a fluctuation range of ≤±1℃, ±3% RH, and ±0.5%. The salt mist system includes a salt solution tank (with a weighing module and a concentration proportioning module built-in), an electric mixer, an atomizing nozzle (with a salt mist particle size of ≤10μm), and a corrosion-resistant drainage tank (316L stainless steel), realizing recycling of salt solution.

[0018] The shear box assembly includes an upper shear box and a lower shear box, the lower shear box is fixed to a track bearing plate at the bottom, and is connected to the horizontal push-pull rod through an adapter block. The track plate is provided with a slide rail and a slide block on both sides to ensure smooth movement of the whole along the slide rail when the horizontal force is loaded.

[0019] The pull-out test box is fixed by a standardized bolt interface with a pressure plate, the geosynthetic material is clamped by a clamp, one end is connected with a horizontal push-pull rod, and the other end is limited in displacement by a middle stopper. The stopper is fixed between double tracks to prevent lateral deviation of the sample during the test.

[0020] The horizontal push-pull rod is connected with the adapter block and the pull-out clamp by means of a latch, and the switch between the direct shear mode and the pull-out mode can be completed within 10 seconds; the shear box and the pull-out test box are quickly installed by means of a pre-positioning pin and a bolt.

[0021] The visual monitoring assembly includes: a fog-proof observation window (double-layer heated glass), a high-speed camera (magnetically attracted base fixed, frame rate ≥1000fps), and a miniature CT scanner (including a lead shielding layer, resolution 10μm), which are synchronously collected in linkage with the loading system.

[0022] The sensor system includes: A horizontal load sensor: real-time monitoring of horizontal thrust or tension, with a range of 0-50kN and an accuracy of ±0.5% FS; A displacement sensor: combination of a laser displacement meter and an LVDT for synchronous collection of shear displacement, pull-out displacement and normal deformation data; A temperature, humidity and salinity sensor: arranged at the four corners of the environmental box and the surface of the sample, verified by thermocouple, infrared temperature measurement module and salinity electrode to ensure the reliability of environmental data.

[0023] A data integration module: all sensor signals and image data are connected to the central controller through a universal data port, supporting real-time display, storage and post-processing analysis.

[0024] The horizontal force loading mechanism is equipped with a high-precision servo motor, supporting constant load mode (stress control) and step loading mode. During the test, the displacement sensor continuously monitors the creep displacement, and the data acquisition system records at a frequency of 1Hz, with a single test lasting more than 30 days, meeting the long-term creep characteristic research requirements.

[0025] Both horizontal and vertical loading systems are provided with mechanical limit and electronic overload alarm, and automatically stop when the load is over-limited.

[0026] The surface of the slide rail is coated with a wear-resistant lubricating coating and is equipped with an automatic oil injection device to ensure smooth movement during long-term use.

[0027] Compared with existing test systems, the significant advantages of the present application are: 1) The application is designed with a standardized interface and an adapter interface, so that the sample device and the fixing clamp can be flexibly assembled with the shared push-pull rod and the telescopic fixing rod, relying on the same horizontal and vertical force loading mechanism, the application can complete the application and collection of various types of forces, greatly reducing the cost investment and structural complexity of the equipment. The key technical innovation of the multifunctional integration is reflected in the following two aspects: ① Core loading platform and multi-module compatible design: one loading system platform, controlled by a servo motor and a hydraulic servo system, realizes horizontal / vertical loading; realizes the sharing of six types of test functions such as direct shear, pull-out, creep, puncture, stretching and crushing; all function mode switching components (such as shear box, pull-out box, puncture head, clamp, etc.) adopt standardized adapter interface (bolt / pin), quick disassembly and assembly, mode switching can be completed within a few minutes. ② Flexible adaptation of dynamic loading mode: the servo motor and the hydraulic system can be flexibly switched to static, dynamic or creep loading mode according to the test requirements, fully meeting the diversified requirements of different test scenarios for loading mode.

[0028] 2) The application adopts an integrated environmental temperature and humidity salinity control box, which has a wide temperature control range (-50℃ to 200℃), a wide humidity range (10% RH to 95% RH) and adjustable salinity (0-40%), and can simulate extreme climate conditions in marine engineering (such as freeze-thaw cycle and high-temperature high-salinity foundation). The temperature and humidity, salinity sensors and mechanical data are collected synchronously, supporting multi-environmental parameter-stress-strain coupling analysis, and filling the gap of traditional equipment in the interface creep research under marine extreme environment.

[0029] 3) The application can be compatible with multi-size sample tests, the upper shear box has multiple sizes and models, and the loading system can set the size area to accurately convert and collect the stress, meeting the testing of different size samples. BRIEF DESCRIPTION OF DRAWINGS

[0030] Fig. 1 is a front view of the test system of the application; Fig. 2 is a right view of the test system of the application; Fig. 3 is a left view of the test system of the application; Fig. 4 is a top view of the test system of the application; Fig. 5 is an internal schematic diagram of the shear / creep mechanics test state of the application; Fig. 6 is an internal schematic diagram of the pull-out mechanics test state of the application; Fig. 7 is an internal schematic diagram of the geosynthetic material tensile puncture mechanics test state of the application; Fig. 8 is an internal schematic diagram of the single particle crushing mechanics test state of the application; Fig. 9 is a top view of the internal structure of the pure soil direct shear test state of the application; Fig. 10 is a top view of the internal fixture configuration of the direct shear test state of the present application; Fig. 11 is a top view of the internal track of the present application; Fig. 12 is an internal structure diagram of the integrated environmental temperature and humidity salinity control box of the present application; Fig. 13 is a front view of the upper shear box of the present application; Fig. 14 is a front view of the lower shear box of the present application; Fig. 15 is a front view of the horizontal push-pull rod adapter block of the present application; Fig. 16 is a top view of the horizontal push-pull rod adapter block of the present application; Fig. 17 is a front view of the pull-out box of the present application; Fig. 18 is a front view of the geosynthetic material fixture of the present application; Fig. 19 is a side view of the geosynthetic material fixture of the present application; Fig. 20 is a front view of the conical piercing head of the present application; Fig. 21 is a front view of the salt solution water tank of the present application; Fig. 22 is a top view of the micro-CT scanner of the present application; Fig. 23 is a side view of the high-speed camera of the present application; Fig. 24 is a top view of the visualization module assembly platform of the present application; Fig. 25 is a side view of the visualization module assembly platform of the present application; Fig. 26 is a time-shear displacement relationship curve diagram of Example 1 of the present application; Fig. 27 is a displacement-shear stress relationship diagram of Example 2 of the present application; Fig. 28 is a broken strength-single particle survival probability relationship curve diagram of Example 3 of the present application; Fig. 29 is a shear displacement-shear stress relationship curve diagram of Example 5 of the present application; Reference signs shown in the figures: Data acquisition system 1, environmental temperature and humidity salinity box 2, threaded column 3, sensor 4, horizontal push-pull rod 5, adapter block 6, horizontal push rod 7, pressure plate 8, upper shear box 9, lower shear box 10, pull-out box 11, water tank 12, direct shear fixture 13, pull-out fixture 14, geosynthetic material fixture 15, vertical pressure rod 16, detachable piercing device 17, sliding block 18, track 19, stop block 20, salt solution water tank 21, salinity sensor 22, electric mixer 23, atomizing nozzle 24, corrosion-resistant drainage tank 25, anti-fog observation window 26, high-speed camera 27, micro-CT scanner 28. DETAILED DESCRIPTION

[0031] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0032] Example 1 like Figures 1-4 As shown, this invention discloses a multifunctional geotechnical mechanics testing system for temperature, humidity, and salinity control under extreme environments. Through combined temperature and humidity control, it is adaptable to large-scale applications and includes visualization modules (such as...). Figure 24 , 25 Core innovations include (as shown), and the ability to achieve multi-directional force loading through standardized interfaces. This enables tests such as direct shear / creep, pull-out, single-particle crushing, and geosynthetic tensile / puncture tests, and supports the study of the mechanical properties of large-scale specimens under extreme temperature and humidity coupling conditions. Furthermore, it provides visualization of the experimental process, thus supplementing the research in this area. For example... Figure 1 The structural diagram is the main view of the test system, mainly consisting of threaded column 3, vertical pressure rod 16, horizontal push rod 7, anti-fog observation window 26, sensor 4, data acquisition system 1, horizontal push-pull rod 5, and adapter block 6 (its main view and top view are shown in the diagram). Figure 15 , 16 As shown in the diagram. (As shown in the diagram) Figure 5 This is a structural diagram of Embodiment 1, which consists of a threaded column 3, a vertical pressure rod 16, and an upper shear box 9 (its main view is shown below). Figure 13 (as shown), horizontal push rod 7, lower shear box 10 (its main view is shown) Figure 14 (As shown), slider 18, pressure plate 8, anti-fog observation window 26, water tank 12, high-speed camera 27 (its side view is shown) Figure 23 It consists of sensor 4, data acquisition system 1, horizontal push-pull rod 5 and adapter block 6, as shown, and is used for direct shear creep experiments. Figure 9 This is a top view of the internal structure of pure soil under direct shear test conditions. Figure 10 This is a top view of the internal fixture structure during a direct shear test, which includes a water tank 12, a direct shear fixture 13, and a track 19. Figure 11 This is a top view of the internal track, which mainly consists of track 19 and stop block 20. Regarding the temperature and humidity control section, according to... Figure 12 The internal structure diagram of the integrated environmental temperature, humidity, and salinity control box shows the salt solution tank 21 (its main view is shown below). Figure 21 The system consists of a salinity sensor 22, an electric stirrer 23, and an atomizing nozzle 24 (as shown in the image). The specific salt solution tank can be seen in the image. Figure 21 The device consists of a salinity sensor 22, an electric stirrer 23, and an atomizing nozzle 24. The specific steps of the direct shear creep experiment are as follows: ① Place the two threaded holes on the bottom of the adapter block opposite the two welded screws on the rail plate on the rail plate, connect the horizontal push-pull rod to the left side of the adapter block, insert the cylindrical pin into the circular hole on the upper surface of the adapter block, and connect the horizontal push rod to the right side of the adapter block. ② Fix the lower shear box and the sink as a whole on the pressure bearing plate. ③ Fix the geosynthetic material, lay the geosynthetic material on the surface of the sink, and cover the six conical holes on the surface of the sink below the shear test geosynthetic material clamp, then fix the geosynthetic material with the sink through the shear test geosynthetic material clamp (the front view and side view thereof are shown in Figure 18 、 19 ), and the fixed geosynthetic material should ensure complete coverage of the surface in contact with the upper shear box and be flat without wrinkles. ④ Prepare the sample, place the upper shear directly above the geosynthetic material and completely cover the surface in contact with the upper shear box, and load the sample with a length, width, and height of 300x300x75mm according to the test requirements. ⑤ Adjust the distance between the horizontal bar and the upper shear box by rotating the rotating disc, so that the horizontal bar is in contact with the right side of the upper shear box. In this way, the upper shear box can be kept from moving to the right without rotating the rotating disc. ⑥ According to the test requirements, set the temperature and humidity (such as 40℃, 80% RH), salinity (5%), normal stress, normal stress loading speed, steps, test direction, constant stress control mode, control value, control parameter, switching condition, pause time, and cycle number, etc. data through the computer instrument operation software, and then perform the test. ⑦ The test will first load the normal stress, and load to the set normal stress according to the normal stress loading speed, and maintain it. ⑧ When the set normal stress is reached and stabilized, the horizontal push rod is in contact with the left side of the lower shear box, and starts to push the lower shear box, the sink, and the geosynthetic material fixed with the sink as a whole along the contact surface between the geosynthetic material and the sample to perform the shear test under the creep condition. ⑨ Start the high-speed camera simultaneously to record the interface shear process; after the test is completed, CT scan the sample to analyze the distribution of salt crystals inside the sample. ⑩ After the test is completed, the software will automatically generate the shear stress and deformation relationship curve, force and time relationship curve, temperature and humidity salinity-stress coupling curve, and calculate the cohesion between the geosynthetic material and the soil sample, the friction angle, and the friction ratio. The time-shear displacement relationship curve of the direct shear creep test at 60℃ is shown in Figure 26 .

[0033] Example 2 Unlike the implementation case 1, the functional mode switching assembly of this embodiment includes a tensile mechanical test module, as shown in Figure 6 , which mainly consists of a threaded column 3, a sensor 4, an anti-fog observation window 26, a micro-CT scanner 28 (the top view thereof is shown in Figure 22 ), a tensile clamp 14, a tensile box 11 (the front view thereof is shown in Figure 17 ), and a data acquisition system 1. The tensile test process using this example is as follows: ①Loosen the fixing nut of the shear box and the pressure plate, remove the upper and lower shear boxes, and fix the pull-out test box on the pressure plate by screws. ②Place the two screws welded on the rail plate on the two screw holes at the bottom of the geosynthetic material pull-out test fixture, connect the horizontal push-pull rod to the left side of the fixture, add the test sample into the pull-out test box, and when the test sample is almost flush with the left side hole in the pull-out test box, place the geosynthetic material along the hole, and fix the geosynthetic material on the right side of the hole with the fixture. ③The test requires a test sample with a length, width and height of 250x200x75mm. ④According to the test requirements, set the temperature and humidity (such as 0℃, 20℃, 40℃, 60℃ and 80℃, 60% RH), salinity (10%), normal stress, normal stress loading speed, steps, test direction, constant stress control mode, control value, control parameter, switching condition, pause time, cycle number and other data through the computer instrument operation software, and then perform the test. ⑤The test will first adjust the environmental parameters to the set value, and then load the normal stress after consolidation for 2 hours. According to the normal stress loading speed, load to the set normal stress, and maintain it. After reaching the set normal stress and stabilizing, the horizontal push-pull rod starts to pull out the geosynthetic material, and performs the pull-out test under the condition of creep. ⑥The high-speed camera records the sliding process of the geogrid-saline soil interface in real time; after the test is completed, the CT scan analyzes the corrosion of the grid ribs. ⑦After the test is completed, the software will automatically generate the shear stress and deformation relationship curve, force and time relationship curve, temperature and humidity salinity-stress coupling curve, and calculate the cohesion between the geosynthetic material and the soil sample, the friction angle and the friction ratio.

[0034] Pull-out test record: 1. Screen the calcareous sand and Fujian standard sand samples, strictly control the particle size distribution curve of each group of samples to remain consistent, and divide each group of samples into three times for loading. After loading the test sample each time, the test sample is subjected to compaction treatment.

[0035] 2. Apply vaseline to the left side of the drawing box to reduce the friction between the geogrid and the drawing box during the drawing process. After the first sample is filled, put the geogrid into the left side of the drawing box and connect it with the clamp connected to the horizontal sensor on the left side. Tighten the clamp bolt to fix the geogrid, then fill the second and third samples. For different particle sizes of calcareous sand and Fujian standard sand, control the weight of each group of samples to remain consistent. After the sample is filled, level and compact the top of the sample, cover the upper loading plate, and contact the normal stress loading rod with the upper loading plate through software control to achieve the specified normal stress. Turn on the environmental temperature box and set the predetermined test environment to allow the sample to consolidate for two hours under the specified environmental conditions to ensure that the inside and outside of the sample reach the preset temperature, humidity, and salinity. Then, clear the data in the software. The drawing rate of the test is set to 1 mm / min, the normal stress is set to 20 kPa, 35 kPa, and 50 kPa, the test temperature is set to (0℃, 20℃, 40℃, 60℃, and 80℃), the humidity is set to 60% RH, and the salinity is set to 10%. The displacement-shear stress relationship diagram is shown in Figure 27 Table 1 shows the data of the coral sand-geogrid drawing test.

[0036] Table 1 Coral sand-geogrid drawing test data Example 3 Unlike Example 2, the functional mode switching assembly of this example includes a single particle crushing test test module, as shown in Figure 8 which includes a lower shear box 10, test pads, and the like. The process of performing a single particle crushing test on coral sand using this example is as follows.

[0037] ① Place the two threaded holes on the bottom of the adapter block opposite the two welded screws on the rail plate on the rail plate, connect the horizontal push-pull rod to the left side of the adapter block, insert the cylindrical pin into the circular hole on the upper surface of the adapter block, and connect the horizontal push rod to the right side of the adapter block. ② Fix the lower shear box and the sink as a whole on the pressure plate. ③ The temperature control single particle crushing experiment is carried out according to the requirements of GB-T44750-2024 specification. ④ The selected calcareous sand single particle is washed with clean water and soaked for 24 hours. The dust on the surface of the calcareous sand is completely washed away to ensure that the test results are not affected by external dust. ⑤ Dry the calcareous sand single particle at 80°C. ⑥ Place the calcareous sand single particle in the environmental temperature and humidity salinity box, set the temperature to 40°C, the humidity to 50% RH, and the salinity to 10%, and preheat for 1 hour. ⑦ Place a calcareous sand single particle in the middle of the upper and lower loading plates, control the vertical loading rod to descend, and when the software acquisition system displays the loading force, it indicates that the upper loading plate has just contacted the calcareous sand particle, stop the vertical loading rod from descending and reset the vertical displacement. Continue to operate the vertical loading rod until the particle is crushed, and simultaneously start the CT scanner to record the internal pore evolution of the particle in real time. ⑧ Continue to operate the vertical loading rod until the software acquisition system shows that the loading force has rapidly decreased, indicating that the calcareous sand single particle has been crushed. The maximum loading force measured is the peak load of the calcareous sand single particle. ⑨ After the test is completed, generate the crushing strength-salinity relationship curve and analyze the weakening effect of salt crystallization on the crushing strength.

[0038] The temperature is 0°C, 40°C, 80°C, the humidity is 50% RH, and the salinity is 10%. The single particle crushing test of calcareous sand is shown in Figure 28 .

[0039] Example 4 The functional mode switching assembly of this embodiment includes a geosynthetic tensile puncture test module, as shown in Figure 7 , which includes a threaded column 3, a detachable puncture device 17 (a conical puncture head front view is shown in Figure 20 ), a horizontal push rod 7, a geosynthetic material clamp 15, a rail 19, and a fog-proof observation window 26. The process of conducting a geosynthetic tensile puncture test using this embodiment is as follows: ① Remove the water tank and the lower shear box. ② Connect the geosynthetic material adapter clamp to the right side fixed rod and connect the pulling clamp to the left side horizontal push-pull rod, ensuring that the two are in the same horizontal plane. ③ Fix the geosynthetic material to be tested at both ends of the clamp. ④ Turn on the environmental temperature and humidity salinity box and set the temperature to 60℃, the humidity to 90% RH, and the salinity to 8%, and preheat for 2 hours. ⑤ Turn on the loading system, move the horizontal push-pull rod to the left, and perform the tensile test. The high-speed camera records the tensile deformation process of the material. ⑥ Connect the geosynthetic material piercing device to the vertical pressure rod, turn on the loading system, and apply a normal stress to the geosynthetic material downward from the vertical loading rod to perform the piercing test. Record the correlation between the peak piercing force and the salinity.

[0040] Example 5 Unlike Example 4, the functional mode switching assembly of this example includes a direct shear test module, as shown in Figure 9 The process of performing a pure soil direct shear test using this example is as follows: ① Keep the water tank and the lower shear box switching device (a hollow water tank with an opening of 300x300mm, see the attached Figure 5 ). ② Screen the calcareous sand sample and strictly control the particle size distribution curve of each group of samples to remain consistent. ③ Fill the lower shear box with the sample, which is divided into three times. After each time of sample filling, the sample is compacted. ④ After the lower shear box sample is filled, the upper shear box is installed and connected with the right side bolt. ⑤ Then fill the upper shear sample, which is also divided into three times. After each time of sample filling, the sample is compacted. ⑥ After the sample is filled, the top of the sample is leveled and compacted, and the upper loading plate is covered. ⑦ The software-controlled normal stress loading rod is in contact with the upper loading plate and reaches the specified normal stress. ⑧ Turn on the environmental temperature and humidity salinity control box and set the predetermined test environment. Let the sample consolidate for two hours under the set environmental conditions to ensure that the inside and outside of the sample reach the preset conditions. Then, the software data acquisition system is cleared. ⑨ Set the test shear rate to 1mm / min, the normal stress to 35kPa, the test temperature to 0℃, 40℃, 80℃, the humidity to 50% RH, and the salinity to 10%. ⑩ When the shear displacement reaches 60mm, the test is completed.

[0041] The shear displacement-shear stress relationship curve of the calcareous sand pure soil direct shear test under 35kPa, temperatures of 0℃, 40℃, 80℃, humidity of 50% RH, and salinity of 10% is shown in Figure 29 .

[0042] Example 6 The present embodiment adopts the multifunctional geotechnical mechanics test system for temperature, humidity and salinity control in extreme environment disclosed in the present application to perform a salt spray corrosion test on coral sand-geogrid pullout. Specifically, ① install the pullout box and the geogrid according to the steps in Embodiment 2, and load the coral sand sample. ② Set the salt spray environment: salinity 5%, temperature 40℃, humidity 80% RH, and spray the salt solution into the box for continuous corrosion for 24 hours. ③ Install a high-speed camera, aim at the geogrid-saline soil interface, and record the interface slip process caused by salt crystallization. ④ Load according to the pullout test steps until the sample is destroyed. ⑤ After the pullout test, switch to a CT scanner to analyze the internal corrosion microcracks of the geogrid ribs, and generate a salinity-interface bonding strength attenuation curve.

[0043] Embodiment 7 The present embodiment adopts the multifunctional geotechnical mechanics test system for temperature, humidity and salinity control in extreme environment disclosed in the present application to perform a salt spray corrosion test on coral sand-geogrid pullout. Specifically, ① install the pullout box and the geogrid according to the steps in Embodiment 2, and load the coral sand sample. ② Set the salt spray environment: salinity 5%, temperature 40℃, humidity 80% RH, and spray the salt solution into the box for continuous corrosion for 24 hours. ③ Install a high-speed camera, aim at the geogrid-saline soil interface, and record the interface slip process caused by salt crystallization. ④ Load according to the pullout test steps until the sample is destroyed. ⑤ After the pullout test, switch to a CT scanner to analyze the internal corrosion microcracks of the geogrid ribs, and generate a salinity-interface bonding strength attenuation curve.

[0044] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed in the present application, and these modifications or replacements should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multifunctional geotechnical test system for temperature, humidity and salinity control in extreme environments, characterized by: The application relates to a horizontal force loading mechanism, a vertical loading device, a temperature and humidity and salinity control system, a modular test assembly, a visual monitoring assembly and a data acquisition system. The horizontal force loading mechanism is composed of a threaded column (3), a sensor (4), a horizontal push-pull rod (5) and a motor driving unit; the sensor (4) comprises a horizontal load sensor and a displacement sensor and is used for monitoring horizontal thrust / tension and displacement data in real time. The vertical loading device adopts a hydraulic servo system and is used for applying normal stress. The temperature and humidity and salinity control system is integrated in an environmental temperature and humidity and salinity box, the temperature control range is -50 DEG C to 200 DEG C, the humidity control range is 10% RH to 95% RH, the salinity control range is 0-40%, and the temperature and humidity and salinity control system is provided with a thermocouple, a temperature and humidity sensor, a salinity sensor and an infrared temperature measurement module. The modular test assembly comprises a replaceable shear box, a tensile test box, a geosynthetic material puncture device and an adaptive clamp; the shear box and the tensile test box are connected with a pressure plate through a standardized bolt interface and support the switching of direct shear, tensile and creep test modes; and the geosynthetic material puncture device and the adaptive clamp support geogrid puncture and stretching experiments. The visual monitoring assembly comprises an anti-fog observation window (26), a high-speed camera (27) and a micro-CT scanner (28) and supports real-time recording of the micro-damage process of a sample; the frame rate of the high-speed camera is greater than or equal to 1000 fps. The data acquisition system integrates sensor signals and image data through a general data port, records and analyzes load, displacement, temperature and humidity, salinity, creep and microstructure data in real time.

2. The system of claim 1, wherein, The application relates to a long-term creep direct shear or drawing test device for geosynthetic materials, which comprises a data acquisition system (1), an environmental temperature and humidity salinity tank (2), a threaded column (3), a sensor (4), a horizontal push-pull rod (5), an adapter block (6), a horizontal push rod (7), a pressure bearing plate (8), an upper shear box (9), a lower shear box (10), a drawing box (11), a water tank (12), a direct shear clamp (13), a drawing clamp (14), a geosynthetic material clamp (15), a vertical pressure rod (16), a detachable piercing device (17), a sliding block (18), a track (19), a resisting block (20), a salt solution water tank (21), a salinity sensor (22), an electric stirrer (23), an atomizing nozzle (24), an anti-corrosion drainage tank (25), an anti-fog observation window (26), a high-speed camera (27) and a micro-CT scanner (28); the horizontal force loading mechanism is connected and fixed by the threaded column (3), the sensor (4) and the horizontal push-pull rod (5), the vertical loading device is connected and fixed by the sensor (4) and the vertical pressure rod (16), and the loading device is composed of the horizontal force loading mechanism and the vertical loading device; the data acquisition system (1) is closely matched with the sensor (4), the high-speed camera (27) and the micro-CT scanner (28); the environmental temperature and humidity salinity tank (2) is adjusted by a temperature and humidity salinity control system to adjust the temperature, humidity and salt mist concentration in the tank; the adapter block (6) is connected with the horizontal push-pull rod (5) on the left side and connected with the horizontal push rod (7) on the right side to make the two into an integral whole; the lower shear box (10) is fixed on the pressure bearing plate (8) through bolts, the left end of the lower shear box (10) is fixed with the horizontal push rod (7) through bolts, the upper shear box (9) is placed on the water tank (12) and connected with the horizontal push rod (7) on the right end, so that the upper shear box (9) does not move when the lower shear box moves to the right along with the horizontal push-pull rod (5); the upper and lower shear boxes and the water tank are disassembled, the drawing box (11) is fixed on the pressure bearing plate (8) through bolts, the resisting block (20) is located on the left side of the drawing box (11), and the drawing box does not move to the left during the drawing test; the adapter block (6) is disassembled, the left side of the drawing clamp (14) is connected with the horizontal push-pull rod (5); the loading system is started, and the long-term creep direct shear or drawing test under the control of temperature, humidity and salinity can be carried out; the drawing box (11) is disassembled, the lower shear box (10) is fixed on the pressure bearing plate through bolts, the water tank (12) is fixed on the lower shear box, the experimental cushion block is placed, the normal stress loading system, i.e. the vertical pressure rod (16), is loaded downwards, and the soil single-particle crushing test under the control of temperature, humidity and salinity can be carried out. Dismantle the sink (12) and the lower shear box (10), connect the geosynthetic material clamp (15) with the right side fixed rod, connect the pull-out clamp (14) with the left side horizontal push-pull rod (5), ensure that the two are in the same horizontal plane, fix the geosynthetic material to be tested with the clamp, turn on the loading system, and move the horizontal push-pull rod (5) to the left, so that the geosynthetic material tensile test under controllable temperature, humidity and salinity can be carried out; connect the detachable piercing device (17) with the vertical pressure rod (16), turn on the loading system, and carry out the geosynthetic material piercing test under controllable temperature, humidity and salinity.

3. The system of claim 1, wherein: The environmental temperature, humidity and salinity box (2) adopts an intelligent integrated control system, which can accurately adjust the test environment temperature to -50℃ to 200℃, humidity to 10% RH to 95% RH, and salinity to 0-40%; the salt spray control is realized through a salt solution tank (21), an electric mixer (23) and an atomizing nozzle (24), the salt solution tank is provided with an automatic concentration matching module, the salt spray particle size is ≤10μm; the bottom of the box body is provided with an anti-corrosion drainage groove (25) with a 316L stainless steel inner container to collect and filter the residual salt solution; the box is integrated with a high-efficiency circulating air duct design and is provided with a multi-layer heat insulation structure to ensure uniform distribution of temperature, humidity and salinity, temperature fluctuation ≤±1℃, humidity fluctuation ≤±3% RH, and salinity fluctuation ≤±0.5%; the device is provided with a rapid temperature rising and falling device and a salt spray adjusting device to adapt to environmental changes under different working conditions.

4. The system of claim 1, wherein: The system is a large-scale indoor geotechnical mechanics test instrument, the sample box size is 300mm long, 300mm wide and 150mm high, which can simulate the mechanical behavior of large-scale soil structure and geosynthetic material interface in actual marine engineering, and meet the long-term creep test requirements of large-size samples under complex stress-environment coupling conditions.

5. The system of claim 1, wherein, The horizontal force loading mechanism supports long-term creep test, specifically including: a high-precision servo motor providing constant load or step loading mode; a displacement sensor continuously recording creep displacement at a frequency of 1Hz, a single test cycle ≥30 days; a data acquisition system with an overload protection mechanism that automatically stops when the load exceeds the limit.

6. The system of claim 1, wherein, The temperature, humidity and salinity control system is linked with the data acquisition system to generate temperature-humidity-salinity-stress-strain coupling curves for analyzing the mechanical properties of soil-structure interface under complex environment.

7. The system of claim 2, wherein: The system adopts a modular design, so that the direct shear test, the pull-out test, the geosynthetic tensile puncture test and the soil single particle crushing test can be quickly switched and adjusted; the horizontal force loading mechanism remains unchanged in various test modes, and the test mode can be seamlessly switched by replacing the connecting assembly; in the direct shear test mode, the horizontal force loading mechanism is connected with the adapter block (6), used to apply a constant shear force, so that the sample is sheared along the soil-structure interface, thereby determining the shear strength and long-term shear creep characteristics; in the pull-out test mode, the horizontal force loading mechanism is directly connected with the pull-out clamp (14), and by controlling the loading rate and the pull-out force, the deformation mechanism and the interface bonding characteristics of the sample under the pull-out action are studied; in the tensile puncture test mode, the horizontal force loading mechanism is connected with the geosynthetic material, and by controlling the loading rate and the pull-out force, the mechanical properties and deformation mechanism of the geosynthetic material under complex environment are studied; the adapter block (6) adopts a connection mode of a cylindrical pin inserted into a pin hole.

8. The system of claim 2, wherein, The sliding block and the track surface are coated with wear-resistant lubricating coating and are equipped with an automatic oil injection device.

9. The system of claim 2, wherein, The loading device is internally provided with a sensor (4), which can monitor and record the stress, displacement and deformation of the sample in the long-term loading process in real time; the system can carry out long-term creep test under different temperature, humidity and salinity environments by the combined application of the horizontal force loading mechanism and the vertical loading device, and can study the deformation law and strength evolution mechanism of the soil-structure interface under continuous stress; the loading device adopts a stress control mode, and by combining a precision stepping motor with a negative feedback control system, it can ensure that the applied load remains constant over a long period of time.

10. The system of claim 1, wherein: The visual monitoring assembly includes an anti-fog observation window (26), a high-speed camera (27) and a micro-CT scanner (28); the anti-fog observation window (26) adopts double-layer heated glass to eliminate fogging caused by temperature change; the high-speed camera (27) is fixed to the equipment interface through a magnetic base, with a frame rate ≥1000fps, and a synchronous displacement sensor records the sample failure process; the micro-CT scanner (28) contains a lead shielding layer and is linked with the loading system to realize synchronous stress-microstructure analysis.

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