A large-scale on-site triaxial test device

Abstract

The present invention discloses an on-site in-situ triaxial test device. In this solution, four holes are set at the positions corresponding to the counterweights at the lower ends of the left and right sides, so that anchor bars can pass through to play a fixing role. A loading steel plate is welded at the bottom of the beam to provide a jack reaction force. The two ends of the beam are connected to the counterweight support plate under the beam through anchor bars. The counterweight is placed on the support plate, and a first jack is set in the middle. Therefore, the maximum axial force that the first jack can provide is the total weight of the beam and the counterweights at both ends. In addition, the sample is a cylindrical soil body formed by excavation of the earth embankment, similar to the sample in a conventional triaxial instrument. It needs to be covered with a rubber membrane and locked by a steel hoop to achieve sample sealing. After the sample is installed, a pressure chamber is installed, and pressure is applied to the sample by an air compressor. After the pressure stabilizes, the first jack is started to perform a shear test on the sample, and the corresponding test data is collected by a sensor. This solution also has the advantages of simple structure, convenient operation, and easy implementation.

Description

Technical Field

[0001] The present invention relates to the technical field of field test devices, in particular to a field in-situ large-scale triaxial test device. Background Art

[0002] With the expansion of cities, transportation infrastructure such as airports, high-speed railways, and highways have gradually developed from plain areas with simple topography to mountainous and forested areas with complex terrain. This has led to the emergence of a large number of high fill slopes. The main fill materials for high fill slope projects are rockfill or soil-rock mixtures. The shear strength parameters of soil-rock mixtures have a key impact on the stability of fill slopes and the design of their support structures. However, due to the complex material composition, irregular structural distribution, and difficulty in in-situ sampling of soil-rock mixtures, the accurate determination of their shear strength index is very difficult. In-situ large-scale direct shear and push-shear tests, indoor large-scale direct shear, and triaxial tests are usually used for determination.

[0003] Large-scale in-situ shear tests are complex to perform, resulting in relatively low test result precision and prone to discrepancies, but they can reflect the actual strength of the test points at the construction site. Large-scale indoor shear tests are relatively simple to perform, with easily controlled boundary conditions and relatively high test result precision. However, using remolded soil as a proxy for undisturbed soil can lead to significant errors in the test results. In soil-rock fill projects, the soil-rock mixture is compacted layer by layer using a certain compaction energy or tapping energy to form an artificial fill slope. The mechanical properties of the compacted soil-rock fill differ from both the undisturbed soil on site and the remolded soil indoors, and are affected by the compaction energy and compaction method. Therefore, the shear strength indices measured using in-situ tests on natural soil-rock mixtures or indoor tests on remolded soil-rock mixtures cannot reasonably reflect the shear strength characteristics of the compacted soil-rock mixture in its in-situ state. Currently, research on the shear strength properties of soil-rock mixtures is typically conducted using scaled-down, reshaped specimens in an indoor environment, due to limitations in specimen and block size. To test soil-rock mixtures in their engineering state (i.e., in-service state after artificial compaction), large-scale on-site direct shear test equipment is available. However, large-scale on-site direct shear tests struggle to control the consolidation and drainage processes of the specimens, making it difficult to accurately measure the shear strength properties of soil-rock mixtures. Triaxial testing, on the other hand, offers better control over the consolidation and drainage processes of the specimens, and current triaxial testing equipment is typically indoors.

[0004] In 2016, Dalian University of Technology successfully developed China's first ultra-large, dual-purpose, static and dynamic triaxial apparatus. However, this ultra-large triaxial apparatus is not simply a scaled-up version of a conventional triaxial apparatus. The complexities involved, such as specimen loading, rubber membranes, measurement methods, and loading equipment, have led to limited experimental research reports to date. This apparatus is an indoor test setup, unlike the large-scale, on-site triaxial test apparatus proposed in this patent. The proposed test setup is removable and disassembled, enabling simple and efficient on-site testing.

[0005] At present, on-site in-situ triaxial testing has not been proposed or used. Similar devices, such as the indoor ultra-large triaxial apparatus developed by Dalian University of Technology, have the following problems: 1. Sample preparation is difficult. The reshaped specimens are made in the device, which cannot ensure that the rockfill is fully compacted, nor can the specimens be prepared in the in-situ state of the on-site engineering project; 2. The device is delicate and complex, and has high requirements for operation; 3. If tests are to be carried out under different conditions, it takes a long time and is inefficient; 4. It is only suitable for indoor use and cannot be used on the engineering site.

[0006] Therefore, the existing technology needs to be further improved and perfected. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an on-site large-scale triaxial test device.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A large-scale, in-situ triaxial testing apparatus primarily comprises an earth embankment, a confining pressure module that applies circumferential pressure to a specimen, and a vertical load module that moves longitudinally along the embankment. The confining pressure module is installed within the embankment and contains the specimen. The vertical load module is mounted on the embankment, with the loading end of the load passing through the confining pressure module and pressing against the specimen.

[0010] Specifically, the confining pressure module includes a pressure chamber, a first bottom plate, an air compressor, a rubber membrane, a first top plate, a second bottom plate, a steel ferrule, and a sensor group. The first bottom plate is arranged in the earth embankment. The pressure chamber is mounted on the first bottom plate and is sealed to the first bottom plate. The output end of the air compressor is connected to the pressure chamber through a hose. The second bottom plate is arranged at the bottom of the sample, and the first top plate is arranged at the top of the sample. The rubber membrane wraps the side of the sample, and the top and bottom of the rubber membrane are sealed to the first top plate and the bottom plate respectively through steel ferrules. The sensor group is respectively arranged in the pressure chamber, in the sample, on the first top plate, and on the first bottom plate, and is used to measure the pressure in the pressure chamber, the pore pressure of the sample, and the compression deformation of the sample.

[0011] As a preferred embodiment of the present invention, the sensor assembly primarily comprises a first pressure sensor, a second pressure sensor, a first displacement sensor, and a second displacement sensor. The first pressure sensor is disposed within a pressure chamber and is used to measure the air pressure within the pressure chamber. The second pressure sensor is disposed within a specimen and is used to measure the pore pressure within the specimen. The first displacement sensor is disposed on the first top plate and is used to measure the vertical displacement of the first top plate. The second displacement sensor is disposed on the first bottom plate and is used to measure the vertical displacement of the first bottom plate.

[0012] As a preferred solution of the present invention, in order to locate the position of the sample and better restore the construction site, the first base plate and the second base plate of the present invention are pre-buried in the earth embankment.

[0013] Specifically, the vertical load module mainly includes a beam, a counterweight block, anchor bars, a counterweight plate, a roller, a first jack, a third pressure sensor for measuring the vertical load, and a sliding unit for reducing the resistance to the mutual movement between the beam and the first jack.

[0014] Specifically, the first jack is placed on the top of the first top plate, and its driving end is connected to the bottom of the sliding unit. The middle part of the beam is arranged on the sliding unit. The counterweight blocks are respectively located at both ends of the beam. The counterweight plate is arranged at the bottom of the counterweight block, and the counterweight block is placed on the counterweight plate. The roller is installed at the bottom of the counterweight plate, and its rolling direction is perpendicular to the length direction of the beam. The roller is pressed on the earth embankment and can roll longitudinally on the earth embankment. The anchor bar is arranged vertically, with its upper end connected to the beam and its lower end connected to the counterweight plate, counterweighting the counterweight plate and the counterweight block to the beam. The third pressure sensor is arranged on the jack, between the jack and the specimen.

[0015] Furthermore, the crossbeam mainly includes a second top plate, a third bottom plate, a partition, a first reinforcing plate, and a second reinforcing plate. The second top plate and the third bottom plate are arranged horizontally and parallel to each other. The partition is vertically arranged between the second top plate and the third bottom plate. The partitions are spaced and evenly distributed between the second top plate and the third bottom plate. The first reinforcing plate and the second reinforcing plate are both arranged between adjacent partitions. The first reinforcing plate and the second reinforcing plate are arranged obliquely and connected to form an X-shaped structure. The first reinforcing plate and the second reinforcing plate are respectively connected to the connection between the second top plate and the partition, and the connection between the third bottom plate and the partition.

[0016] As a preferred embodiment of the present invention, in actual testing, the vertical load device of the present invention further includes a fastening nut, which can be adjusted depending on site conditions. The anchor bar is threaded at both its upper and lower ends. The fastening nuts are located at the junctions between the anchor bar and the top of the second top plate, and at the junction between the anchor bar and the bottom of the counterweight plate. Adjustment of the maximum height of the beam is achieved by simply adjusting the fastening nuts at the upper and lower ends of the anchor bar.

[0017] Furthermore, the sliding module primarily comprises a first steel plate, a bearing seat, a rotating shaft, and bearings. The rotating shaft is mounted on the first steel plate at both ends via the bearing seats. The bearings are arranged side by side on the rotating shaft, with their rolling direction aligned with the longitudinal direction of the crossbeam. The bottom of the steel plate is fixedly connected to the drive end of the first jack.

[0018] Preferably, to facilitate adjustment of the crossbeam height and enhance the integration of the crossbeam and counterweight, the vertical load device of the present invention further includes a second jack. The second jack is mounted on the counterweight, with its top abutting the crossbeam. There are at least two second jacks, which are arranged side by side.

[0019] Furthermore, in order to transmit the thrust force applied by the second jack to the crossbeam more evenly to the crossbeam, the vertical load device of the present invention further includes a fourth steel plate. The fourth steel plate is arranged between the second jack and the crossbeam.

[0020] As a preferred embodiment of the present invention, in order to prevent the counterweight and crossbeam from shaking or moving during testing, the vertical load device of the present invention further comprises a locking block, a first spring, a second spring, and a locking block for locking the roller. The locking blocks are arranged in pairs at the front and rear positions of the roller, and their top ends are connected to the bottom of the counterweight plate through the first spring, so that the locking blocks can rotate around the connection. The locking block is arranged on the back of the locking block, one end of the locking block is connected to the locking block through the second spring, and the other end of the locking block can rotate around the connection and press against the bottom of the counterweight plate to lock the locking block. During use, to lock the roller, the locking block can be rotated downward and contacted with the roller, and at the same time, the locking block can be flipped upward so that the locking block presses against the bottom of the counterweight plate, thereby forming a relatively stable support structure, so that the locking block firmly presses the roller, and when the front and rear locking blocks act on the roller at the same time, they form an embracing posture around the roller, so that the roller is further locked. To release the roller, push the locking block back. At this time, the locking block and the locking block are reset at the same time under the action of the second spring and the first spring respectively. The roller is unlocked. At this time, the entire vertical load device can be pushed forward to roll until it reaches the next specimen.

[0021] As a preferred embodiment of the present invention, to maximize the reproduction of actual construction site conditions, the earth embankment has a trapezoidal cross-section with a slope ratio of 1:1. Rockfill material, used in high fill slope construction, is layered and compacted, with each layer laid and compacted at a thickness of 300 mm. A test trench was also excavated in the center of the earth embankment. Several cylindrical specimens were excavated from the trench and placed side by side within the trench.

[0022] Furthermore, the earth embankment is provided with a track for facilitating the movement of the vertical load module, and the track is laid at the top of the earth embankment.

[0023] As a preferred solution of the present invention, in order to improve the overall rigidity of the confining pressure module, the pressure chamber, the first bottom plate, the first top plate and the second bottom plate of the present invention are all made of steel plate structures.

[0024] The present invention also discloses a construction method based on an on-site large-scale triaxial test device, which mainly includes the following steps:

[0025] Step S1: Build an earth embankment at the construction site that is 2 meters high, 18 meters wide, and approximately 40 meters long with a slope ratio of 1:1. The earth embankment is constructed using rockfill materials used to build high fill slopes, which are compacted layer by layer. Simultaneously, a series of components are pre-embedded, and are laid and compacted in layers approximately 300 mm thick.

[0026] Step S2: A rectangular steel plate (first bottom plate) that fits the pressure chamber is embedded in the earth embankment. A circular steel plate (second bottom plate) with the same area as the bottom of the specimen is placed in the center of the rectangular steel plate. The two steel plates are placed at the bottom of the specimen to be excavated.

[0027] Step S3: dig out four cylindrical specimens of a certain size from the constructed earth embankment and arrange the specimens at intervals;

[0028] Step S4: Arrange the track on the top of the constructed test embankment and set up the vertical load module;

[0029] Step S5: Place a rubber membrane on the first specimen undergoing the triaxial test. Secure the rubber membrane to the circular steel plates above and below the specimen (i.e., the first top plate and the second bottom plate, where the first top plate is placed after excavation and the second bottom plate is pre-buried). Place a steel ferrule on the membrane and lock it. Then, place a pressure chamber on the membrane. The pressure chamber can be engaged with the pre-buried rectangular steel plate (the first bottom plate) at the bottom. Install a second displacement sensor on the pre-buried steel plate, and install a vertical load module directly above the specimen.

[0030] Step S6: The pressure chamber and the steel plate above the sample have many prefabricated holes. A series of sensors and components for monitoring are installed through the prefabricated holes. The sensors include pressure sensors and displacement sensors, while the components include the first jack and the hose of the air compressor.

[0031] Step S7: Start the air compressor to provide a certain pressure for the sample, and then the first jack starts to operate until the sample is broken, while recording all data (including the data of the sensor group);

[0032] Step S8: Move the entire vertical load module to the top of the second test specimen via the pulley under the counterweight support plate and the track at the top of the embankment. Repeat steps 5-7 while recording all data. Repeat the above operations for the third and fourth specimens.

[0033] The working process and principle of the present invention are as follows: The crossbeam of this solution is constructed of H-shaped steel with ribs and tie plates. Four holes are provided on the upper and lower sides of the crossbeam, corresponding to the counterweights at the lower ends of the left and right sides, to facilitate the insertion of anchor bars (which can be threaded steel bars) for securing the specimen. A loading steel plate is welded to the center bottom of the crossbeam to provide the reaction force for the jack. The entire crossbeam structure is shaped like a shoulder pole. Anchor bars connect the ends of the crossbeam to the counterweight support plate below the beam. The support plate is equipped with a counterweight (a large rectangular steel plate) that provides the reaction force for the first jack loading the specimen. Therefore, the maximum axial force that the first jack can apply to the specimen is approximately the combined weight of the crossbeam and the counterweights at both ends. Furthermore, the specimen is a cylindrical mass of soil excavated from an earth embankment, similar to that used in conventional triaxial testing. A rubber membrane is applied and sealed with a steel collar. After the specimen is installed, a pressure chamber is installed, and pressure is applied to the specimen using a second pressure sensor. Once the pressure stabilizes, the first jack is activated to perform a shear test on the specimen, and the sensor collects the corresponding test data.

[0034] Compared with the prior art, the present invention also has the following advantages:

[0035] (1) The large-scale on-site triaxial test device provided by the present invention can reduce the influence of scale effect on rockfill materials in conventional indoor triaxial tests, so that the soil properties obtained by triaxial tests are often more accurate.

[0036] (2) The sample preparation method adopted by the on-site large-scale triaxial test device provided by the present invention can ensure the compaction degree of the sample and ensure that the test results are closer to the actual situation.

[0037] (3) The large-scale on-site triaxial test device provided by the present invention can be used to conduct in-situ tests at the engineering site. The test device is mobile and flexible. Compared with indoor triaxial instruments, it has the advantages of reducing the size effect of rockfill materials, easy sample preparation, simple operation and high test efficiency. It can effectively solve the problems of scale effect, sample preparation difficulty and low efficiency encountered in traditional tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a front view of the on-site large-scale triaxial test device provided by the present invention.

[0039] Figure 2 It is a top view of the on-site large-scale triaxial test device provided by the present invention.

[0040] Figure 3 It is a side view of the on-site large-scale triaxial test device provided by the present invention.

[0041] Figure 4 yes Figure 3 A partial enlarged schematic diagram of the dotted circle in the middle.

[0042] Figure 5 It is a structural schematic diagram of the vertical load module provided by the present invention.

[0043] Figure 6 It is a side view of the counterweight structure provided by the present invention.

[0044] Figure 7 It is a partially enlarged schematic diagram of the roller provided by the present invention.

[0045] Description of the reference numerals in the above drawings:

[0046] 1-crossbeam, 2-counterweight, 3-anchor, 4-counterweight plate, 5-roller, 6-first jack, 7-second top plate, 8-third bottom plate, 9-partition, 10-first reinforcement plate, 11-second reinforcement plate, 12-fastening nut, 13-first steel plate, 14-bearing, 15-earth embankment, 16-second jack, 17-fourth steel plate, 18-locking block, 19-locking block, 20-rubber membrane, 21-pressure chamber, 22-sample, 23-second bottom plate, 24-first bottom plate, 25-steel ring, 26-second pressure sensor, 27-first displacement sensor, 28-first pressure sensor, 29-air compressor, 30-hose, 31-first top plate, 32-second displacement sensor. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clear and explicit, the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] Example 1:

[0049] like Figures 1 to 4 As shown, this embodiment discloses a large-scale, in-situ triaxial testing apparatus, which primarily comprises an earth embankment 15, a confining pressure module for applying circumferential pressure to a specimen 22, and a vertical load module movable longitudinally along the earth embankment 15. The confining pressure module is installed within the earth embankment 15, within which the specimen 22 is located. The vertical load module is mounted on the earth embankment 15, with the loading end of the load passing through the confining pressure module and pressing against the specimen 22.

[0050] Specifically, the confining pressure module includes a pressure chamber 21, a first bottom plate 24, an air compressor 29, a rubber membrane 20, a first top plate 31, a second bottom plate 23, a steel ferrule 25, and a sensor group. The first bottom plate 24 is located within the earth embankment 15. The pressure chamber 21 is mounted on the first bottom plate 24 and is sealed thereto. The output end of the air compressor 29 is connected to the pressure chamber 21 via a hose 30. The second bottom plate 23 is located at the bottom of the specimen 22, and the first top plate 31 is located at the top of the specimen 22. The rubber membrane 20 wraps around the sides of the specimen 22, and the top and bottom of the rubber membrane 20 are sealed to the first top plate 31 and bottom plate, respectively, via steel ferrules 25. The sensor group is located within the pressure chamber 21, within the specimen 22, on the first top plate 31, and on the first bottom plate 24, respectively, to measure the pressure in the pressure chamber 21, the pore pressure of the specimen 22, and the compression deformation of the specimen 22.

[0051] As a preferred embodiment of the present invention, the sensor group mainly includes a first pressure sensor 28, a second pressure sensor 26, a first displacement sensor 27, and a second displacement sensor 32. The first pressure sensor 28 is disposed in the pressure chamber 21 and is used to measure the air pressure in the pressure chamber 21. The second pressure sensor 26 is disposed in the specimen 22 and is used to measure the pore pressure of the specimen 22. The first displacement sensor 27 is disposed on the first top plate 31 and is used to measure the vertical displacement of the first top plate 31. The second displacement sensor 32 is disposed on the first bottom plate 24 and is used to measure the vertical displacement of the first bottom plate 24.

[0052] As a preferred solution of the present invention, in order to locate the position of the sample 22 and better restore the construction site, the first base plate 24 and the second base plate 23 of the present invention are pre-buried in the earth embankment 15.

[0053] Specifically, such as Figures 5 to 7 As shown, the vertical load module mainly includes a beam 1, a counterweight block 2, an anchor bar 3, a counterweight plate 4, a roller 5, a first jack 6, a third pressure sensor for measuring the vertical load, and a sliding unit for reducing the resistance to the mutual movement of the beam 1 and the first jack 6.

[0054] Specifically, the first jack 6 is placed on the top of the first top plate 31, and its driving end is connected to the bottom of the sliding unit. The middle part of the beam 1 is arranged on the sliding unit. The counterweight blocks 2 are respectively located at both ends of the beam 1. The counterweight plate 4 is arranged at the bottom of the counterweight block 2, and the counterweight block 2 is placed on the counterweight plate 4. The roller 5 is installed at the bottom of the counterweight plate 4, and its rolling direction is perpendicular to the length direction of the beam 1. The roller 5 is pressed on the earth embankment 15 and can roll longitudinally on the earth embankment 15. The anchor bar 3 is arranged vertically, with its upper end connected to the beam 1 and its lower end connected to the counterweight plate 4, counterweighting the counterweight plate 4 and the counterweight block 2 to the beam 1. The third pressure sensor is arranged on the jack, between the jack and the specimen 22.

[0055] Furthermore, the crossbeam 1 mainly includes a second top plate 7, a third bottom plate 8, a partition 9, a first reinforcing plate 10, and a second reinforcing plate 11. The second top plate 7 and the third bottom plate 8 are arranged horizontally and parallel to each other. The partition 9 is vertically arranged between the second top plate 7 and the third bottom plate 8. The partitions 9 are spaced and evenly distributed between the second top plate 7 and the third bottom plate 8. The first reinforcing plate 10 and the second reinforcing plate 11 are both arranged between adjacent partitions 9. The first reinforcing plate 10 and the second reinforcing plate 11 are arranged obliquely and connected to form an X-shaped structure. The first reinforcing plate 10 and the second reinforcing plate 11 are respectively connected to the connection between the second top plate 7 and the partition 9 and the connection between the third bottom plate 8 and the partition 9.

[0056] As a preferred embodiment of the present invention, in actual testing, the vertical load device of the present invention further includes a fastening nut 12, which may be required to adjust the jacking height of the beam 1 due to varying site conditions. The anchor bar 3 is threaded at both its upper and lower ends. The fastening nuts 12 are located at the junctions between the anchor bar 3 and the top of the second top plate 7, and between the anchor bar 3 and the bottom of the counterweight plate 4. During adjustment, the maximum height of the beam 1 can be adjusted by simply adjusting the fastening nuts 12 at the upper and lower ends of the anchor bar 3.

[0057] Furthermore, the sliding module primarily comprises a first steel plate 13, a bearing seat, a rotating shaft, and bearings 14. Both ends of the rotating shaft are mounted on the first steel plate 13 via the bearing seats. The bearings 14 are arranged side by side on the rotating shaft, with their rolling direction aligned with the length of the crossbeam 1. The bottom of the steel plate is fixedly connected to the drive end of the first jack 6.

[0058] Preferably, to facilitate adjustment of the height of the beam 1 and improve the integration of the beam 1 and the counterweight, the vertical load device of the present invention further includes a second jack 16. The second jack 16 is disposed on the counterweight, with its top abutting against the beam 1. There are at least two second jacks 16, which are disposed side by side.

[0059] Furthermore, in order to transmit the thrust force applied by the second jack 16 to the beam 1 more evenly to the beam 1 , the vertical load device of the present invention further includes a fourth steel plate 17 . The fourth steel plate 17 is disposed between the second jack 16 and the beam 1 .

[0060] As a preferred embodiment of the present invention, to prevent the counterweight and beam 1 from shaking or moving during testing, the vertical load device of the present invention further includes a locking block 18, a first spring, a second spring, and a locking block 19 for locking the roller 5. The locking blocks 18 are arranged in pairs at the front and rear positions of the roller 5, and their top ends are connected to the bottom of the counterweight plate 4 via the first spring, allowing the locking blocks 18 to rotate around the connection. The locking block 19 is arranged on the back of the locking block 18, and one end of the locking block 19 is connected to the locking block 18 via the second spring. The other end of the locking block 19 can rotate around the connection and press against the bottom of the counterweight plate 4 to lock the locking block 18. During use, to lock the roller 5, the locking block 18 can be rotated downward to contact the roller 5. At the same time, the locking block 19 can be flipped upward so that the locking block 19 presses against the bottom of the counterweight plate 4, thereby forming a relatively stable support structure, so that the locking block 18 firmly presses the roller 5. When the front and rear locking blocks 18 act on the roller 5 at the same time, they form an embracing posture around the roller 5, further locking the roller 5. To release the roller 5, the locking block 19 can be pushed back. At this time, the locking block 19 and the locking block 18 are simultaneously reset under the action of the second spring and the first spring respectively, and the roller 5 is unlocked. At this time, the entire vertical load device can be pushed forward to roll until it reaches the next specimen 22.

[0061] As a preferred embodiment of the present invention, to maximize the reproduction of actual construction site conditions, the earth embankment 15 has a trapezoidal cross-section with a slope ratio of 1:1. Rockfill material, used in high-fill slope construction, is layered and compacted, with each layer being laid and compacted at a thickness of 300 mm. A test trench is also excavated in the center of the earth embankment 15. Several cylindrical specimens 22 are excavated from the test trench and placed side by side within the test trench.

[0062] Furthermore, a track is provided on the earth embankment 15 to facilitate the movement of the vertical load module. The track is laid at the top of the earth embankment 15.

[0063] As a preferred solution of the present invention, in order to improve the overall rigidity of the confining pressure module, the pressure chamber 21, the first bottom plate 24, the first top plate 31 and the second bottom plate 23 of the present invention are all made of steel plate structures.

[0064] The present invention also discloses a construction method based on an on-site large-scale triaxial test device, which mainly includes the following steps:

[0065] Step S1: Build an earth embankment 15 at the construction site with a height of 2 meters, a width of 18 meters, a length of approximately 40 meters, and a slope ratio of 1:1. The earth embankment 15 is made of rockfill materials used to build high fill slopes, which are rolled layer by layer. At the same time, a series of components are pre-embedded and laid in layers of approximately 300 mm thickness and then rolled.

[0066] Step S2: A rectangular steel plate (first bottom plate 24) that fits the pressure chamber 21 is embedded in the earth embankment 15. A circular steel plate (second bottom plate 23) with the same area as the bottom of the specimen 22 is placed in the center of the rectangular steel plate. The two steel plates are placed at the bottom of the specimen 22 to be excavated.

[0067] Step S3: dig out four cylindrical specimens 22 of a certain size from the built earth embankment 15, and arrange the specimens 22 at intervals;

[0068] Step S4: Arrange the track on the top of the constructed test embankment 15 and set the vertical load module;

[0069] Step S5: Place the rubber membrane 20 on the first specimen 22 undergoing the triaxial test. Secure the rubber membrane 20 to the circular steel plates above and below the specimen 22 (i.e., the first top plate 31 and the second bottom plate 23, where the first top plate 31 is placed after excavation and the second bottom plate 23 is pre-buried). Place the steel ring 25 on the rubber membrane and lock it. Then, place the pressure chamber 21 on the rubber membrane. The pressure chamber 21 can be fitted with the pre-buried rectangular steel plate (the first bottom plate 24) at the bottom. Install the second displacement sensor 32 on the pre-buried steel plate. Install the vertical load module directly above the specimen 22.

[0070] Step S6: The pressure chamber 21 and the steel plate above the sample 22 have many prefabricated holes. A series of sensors and components for monitoring are installed through the prefabricated holes. The sensors include pressure sensors and displacement sensors, while the components include the first jack 6 and the hose 30 of the air compressor 29;

[0071] Step S7: Start the air compressor 29 to provide a certain pressure for the sample 22, and then the first jack 6 starts to operate until the sample 22 is broken, while recording all data (including the data of the sensor group);

[0072] Step S8: Move the entire vertical load module to the position directly above the second test specimen 22 via the pulley under the counterweight support plate and the track at the top of the earth embankment 15. Repeat steps 5-7 while recording all data. Repeat the above operations for the third and fourth test specimens 22.

[0073] The working process and principle of the present invention are as follows: The crossbeam 1 of this solution is made of H-shaped steel with ribs and gussets. Four holes are provided on the top and bottom of the crossbeam 1 at the positions corresponding to the counterweights at the lower ends of the left and right sides. These holes facilitate the passage of anchor bars 3 (which can be threaded steel bars) to secure the crossbeam. A loading steel plate is welded to the middle bottom of the crossbeam 1 to provide the jack reaction force. The entire crossbeam 1 structure is shaped like a shoulder pole. The two ends of the crossbeam 1 are connected to the counterweight support plate below the beam via anchor bars 3. The support plate is equipped with a counterweight (a large rectangular steel bar) in the middle to provide the reaction force for loading the first jack 6 on the specimen 22. Therefore, the maximum axial force that the first jack 6 can provide on the specimen 22 is approximately the total weight of the crossbeam 1 plus the counterweights at both ends of the beam. Furthermore, the specimen 22 is a cylindrical soil mass excavated from the earth bank 15, similar to the specimen 22 in a conventional triaxial apparatus. A rubber membrane 20 is applied and locked with a steel hoop to achieve sealing. After the sample 22 is installed, the pressure chamber 21 is installed, and the second pressure sensor 26 is used to apply pressure to the sample 22. After the pressure stabilizes, the first jack 6 is started to perform a shear test on the sample 22, and the corresponding test data is collected using the sensor.

[0074] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A large-scale on-site triaxial test device, characterized in that: The device comprises an earth embankment, a confining pressure module for applying circumferential pressure to the sample, and a vertical load module that can move longitudinally along the earth embankment; the confining pressure module is installed in the earth embankment and contains the sample; the vertical load module is arranged on the earth embankment, and the loading end of the load passes through the confining pressure module and presses the sample; The confining pressure module includes a pressure chamber, a first bottom plate, an air compressor, a rubber membrane, a first top plate, a second bottom plate, a steel ferrule, and a sensor group; the first bottom plate is arranged in the earth embankment; the pressure chamber is mounted on the first bottom plate and is sealed to the first bottom plate; the output end of the air compressor is connected to the pressure chamber through a hose; the second bottom plate is arranged at the bottom of the sample, and the first top plate is arranged at the top of the sample; the rubber membrane wraps the side of the sample, and the top and bottom of the rubber membrane are sealed to the first top plate and the second bottom plate respectively through steel ferrules; the sensor group is respectively arranged in the pressure chamber, in the sample, on the first top plate, and on the first bottom plate, for measuring the pressure in the pressure chamber, the pore pressure of the sample, and the compression deformation of the sample; The vertical load module includes a crossbeam, a counterweight, an anchor bar, a counterweight plate, a roller, a first jack, a third pressure sensor for measuring the vertical load, and a sliding unit for reducing the resistance to mutual movement between the crossbeam and the first jack; The first jack is placed on the top of the first top plate, and its driving end is connected to the bottom of the sliding unit; the middle part of the crossbeam is set on the sliding unit; The counterweights are located at both ends of the beam; the counterweight plate is arranged at the bottom of the counterweight, and the counterweight is placed on the counterweight plate; the roller is installed at the bottom of the counterweight plate, and its rolling direction is perpendicular to the length direction of the beam; the roller is pressed on the earth embankment and can roll longitudinally on the earth embankment; the anchor bar is arranged vertically, with its upper end connected to the beam and the lower end connected to the counterweight plate, so that the counterweight plate and the counterweight are counterweighted to the beam; the third pressure sensor is arranged on the first jack, and is located between the first jack and the specimen; The crossbeam includes a second top plate, a third bottom plate, a partition plate, a first reinforcing plate, and a second reinforcing plate; the second top plate and the third bottom plate are arranged horizontally and parallel to each other; the partition plate is vertically arranged between the second top plate and the third bottom plate; the partition plates are spaced and evenly distributed between the second top plate and the third bottom plate; the first reinforcing plate and the second reinforcing plate are both arranged between adjacent partition plates; the first reinforcing plate and the second reinforcing plate are arranged obliquely and connected to form an X-shaped structure; the first reinforcing plate and the second reinforcing plate are respectively connected to the connection between the second top plate and the partition plate and the connection between the third bottom plate and the partition plate; The cross-section of the earth embankment is trapezoidal, with a slope ratio of 1:

1. The rockfill materials used to build the high fill slope are compacted layer by layer, and are laid and compacted at a thickness of 300 mm. A test trench is also excavated in the middle of the earth embankment. Several cylindrical specimens are dug out from the test trench. The specimens are arranged side by side in the test trench.

2. The on-site large-scale triaxial test device according to claim 1, characterized in that: The sensor group includes a first pressure sensor, a second pressure sensor, a first displacement sensor, and a second displacement sensor; the first pressure sensor is arranged in a pressure chamber to measure the air pressure in the pressure chamber; the second pressure sensor is arranged in a sample to measure the pore pressure of the sample; the first displacement sensor is arranged on a first top plate to measure the displacement of the first top plate in a vertical direction; the second displacement sensor is arranged on a first bottom plate to measure the displacement of the first bottom plate in a vertical direction.

3. The on-site large-scale triaxial testing device according to claim 1, characterized in that: The first bottom plate and the second bottom plate are pre-buried in the earth embankment.

4. The on-site large-scale triaxial testing device according to claim 1, characterized in that: The sliding unit includes a first steel plate, a bearing seat, a rotating shaft, and a bearing; both ends of the rotating shaft are installed on the first steel plate through the bearing seat; the bearings are arranged side by side on the rotating shaft, and their rolling direction is consistent with the length direction of the beam; the bottom of the steel plate is fixedly connected to the driving end of the first jack.

5. The on-site large-scale triaxial testing device according to claim 1, characterized in that: The vertical load module also includes a locking block, a first spring, a second spring, and a locking block for locking the roller; the locking blocks are arranged in pairs at the front and rear positions of the roller, and the top ends thereof are connected to the bottom of the counterweight plate through the first spring, so that the locking block can rotate around the connection; the locking block is arranged on the back side of the locking block, one end of the locking block is connected to the locking block through the second spring, and the other end of the locking block can rotate around the connection and press against the bottom of the counterweight plate to lock the locking block.

6. The on-site large-scale triaxial testing device according to claim 1, characterized in that: The earth embankment is also provided with a track for facilitating the movement of the vertical load module; the track is laid at the top of the earth embankment.

7. The on-site large-scale triaxial testing device according to claim 1, characterized in that: The pressure chamber, the first bottom plate, the first top plate and the second bottom plate are all made of steel plate structures.

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