A soil deformation observation and measurement test device with suction control

Abstract

The application relates to a soil deformation observation and measurement test device with suction control, which comprises a main structure, a water injection system and a suction control system, wherein the main structure comprises an observation top plate, a lateral limit ring, a chamber base, a connecting frame and three sensors, the sensors comprise a laser displacement sensor, a radial force sensor and an axial force sensor, the observation top plate, the axial force sensor and a support plate are fixedly connected through the connecting frame, and the observation top plate, the lateral limit ring and the base constitute a soil sample chamber; the water injection system comprises a pressure volume controller, a water injection system connection switch, the suction control system comprises a porous air bottle, a filter bottle and a gas circulating pump, and the suction control system is connected with a switch and an exhaust port. Compared with the prior art, the application realizes the alternation of dry and wet tests, and visualizes the macroscopic performance of the soil suction change process in the test process.

Description

Technical Field

[0001] This invention relates to the observation and measurement of soil deformation, and in particular to a suction-controlled device for observing and measuring soil deformation. Background Technology

[0002] Unsaturated soils are widely found in common foundation engineering projects such as slopes, embankments, foundation pits, and landfills. As a three-phase system, unsaturated soils, besides the solid phase, have gas and liquid phases that are easily affected by the environment. Changes in the gas-liquid ratio lead to changes in suction, causing a series of strength and deformation problems. For example, collapsible loess, after being soaked in water, experiences a decrease in suction, a significant increase in deformation amount and rate, and ultimately disintegration and collapse. Meanwhile, cohesive soils (such as expansive soil, bentonite, and red clay), due to their characteristic of swelling upon contact with water and shrinking upon loss of water, experience a sharp decline in strength after suction decreases. Although the strength can recover due to increased suction caused by subsequent drying, the drastic volume changes easily lead to cracking. These problems greatly weaken the engineering properties of the soil, adversely affecting engineering construction and jeopardizing the safety of people's lives and property.

[0003] Currently, existing experimental methods are concentrated on unsaturated soil under specific conditions. It is difficult to observe and quantitatively analyze the global macroscopic development process, especially the volume changes and crack propagation phenomena that occur when the soil undergoes changes in suction. This directly hinders the exploration of influencing factors and mechanical mechanisms, and is not conducive to solving existing engineering problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art by providing a suction-controlled soil deformation observation and measurement device. The device realizes the alternation of dry and wet tests, and visualizes the macroscopic manifestation of the soil suction change process during the test.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A suction-controlled soil deformation observation and measurement device includes a main structure, a water injection system, and a suction control system, wherein...

[0007] The main structure includes an observation top plate, side confinement rings, a chamber base, a connecting frame, and three sensors: a laser displacement sensor, a radial force sensor, and an axial force sensor.

[0008] An exhaust vent is installed on the top plate of the observation system, with a permeable stone at the bottom of the vent. Connection holes are also provided in the top plate, and a sealing ring is installed at the bottom of the top plate.

[0009] The top of the chamber base is equipped with a permeable stone and a sealing ring. Pipes are installed inside the chamber base, with a switch at one end and a water inlet at the other.

[0010] The lateral confinement ring is placed between the observation top plate and the base.

[0011] A support plate is installed above the observation ceiling. The laser displacement sensor is located below the support plate and suspended above the observation ceiling. Connection holes are provided on the support plate, and a camera is mounted on the support plate.

[0012] The radial force sensor is embedded in the side confinement ring.

[0013] The axial force sensor is located under the chamber base, and a connection hole is provided on the axial force sensor.

[0014] The observation top plate, axial force sensor and support plate are fixedly connected by a connecting frame. The observation top plate, side confinement ring and base form a soil sample chamber.

[0015] The water injection system includes a pressure and volume controller and a water injection system connection switch.

[0016] The suction control system includes a porous air bottle, a filter bottle, and a gas circulation pump. The suction control system is connected to a switch and an exhaust port.

[0017] Furthermore, the porous ventilation bottle is connected to the filter bottle and the gas circulation pump respectively through a conduit. The filter bottle is connected to the air inlet pipe, the air inlet pipe is connected to the switch, and the gas circulation pump is connected to the exhaust port of the observation top plate through the exhaust pipe. The short pipe of the filter bottle is the air inlet pipe.

[0018] Furthermore, both the porous gas bottle and the filter bottle include a long tube and a short tube. The long tube of the porous gas bottle is connected to the gas circulation pump through a conduit, and the short tube of the porous gas bottle is connected to the long tube of the filter bottle through a conduit. The short tube of the filter bottle is connected to the switch.

[0019] Furthermore, the side confinement ring is a square ring, the permeable stone is a square permeable stone corresponding to the side confinement ring, and the water inlet is a permeable stone.

[0020] Furthermore, the side limiting ring is a side limiting ring with a water inlet channel on the side, the permeable stone is made of impermeable material of the same size as the side limiting ring, and the water inlet is a side limiting ring.

[0021] Furthermore, the connecting frame includes bolts, hexagonal nuts, and cap nuts.

[0022] Furthermore, bolts pass through the connection holes of the support plate, the observation top plate, and the axial force sensor.

[0023] Furthermore, cap nuts are installed on the top of the connecting holes of the bracket plate, and hexagonal nuts are installed on the bottom.

[0024] Furthermore, a cap nut is installed on the top of the connection hole of the observation top plate.

[0025] Furthermore, a hexagonal nut is installed at the bottom of the connection hole of the axial force sensor.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) This invention uses a pressure volume controller and a suction control system connected to a switch and an exhaust port to inject a solution into the soil sample chamber to complete the humidification test. At the same time, a gas circulation pump connected to the exhaust port of the observation top plate is used to gradually balance the soil suction in the soil sample chamber with the suction value in the suction control system to complete the drying test. Finally, the alternation of wet and dry tests is realized to realize the change of soil suction and lay the foundation for the observation of suction change.

[0028] (2) The present invention fixes the observation top plate, axial force sensor and support plate through a connecting frame. A camera is set on the observation top plate. During the test, the macroscopic manifestation of the soil suction change process is visualized, which overcomes the disadvantage that the soil suction change process is not visible in conventional tests and provides the possibility of qualitative description and analysis.

[0029] (3) The present invention embeds a radial force sensor in the side confinement ring, sets an axial force sensor under the chamber base, and sets a laser displacement sensor under the support plate. The mechanical parameters and displacement parameters are measured by the sensors during the soil change process, providing quantitative parameters. The soil morphology development characteristics and physical quantities obtained from the comprehensive analysis of qualitative and quantitative results can provide important information parameters for geological engineering, geotechnical engineering and other related fields. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the present invention;

[0031] Figure 2 This is a structural diagram of the main structure of the present invention;

[0032] Figure 3 This is a structural diagram of the water injection system of the present invention;

[0033] Figure 4 This is a schematic diagram of the suction control system of the present invention;

[0034] In the figure, 1-laser displacement sensor; 2-radial force sensor; 3-axial force sensor; 4-observation top plate; 5-side limiting ring; 6-chamber base; 7-switch; 8-sealing ring; 9-permeable stone; 10-support plate; 11-pressure volume controller; 12-filter bottle; 13-porous vent bottle; 14-gas circulation pump. Detailed Implementation

[0035] 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.

[0036] Example 1:

[0037] This invention proposes a suction-controlled soil deformation observation and measurement device, the overall structure of which is shown in the figure below. Figure 1 As shown. The device includes a main structure, a water injection system, and a suction control system. A structural diagram of the main structure is shown below. Figure 2 As shown. The structural diagram of the water injection system is as follows. Figure 3 As shown in the diagram. A schematic diagram of the suction control system is shown below. Figure 4 As shown.

[0038] The main structure includes an observation top plate 4, a side confinement ring 5, a chamber base 6, a connecting frame, and three sensors: a laser displacement sensor 1, a radial force sensor 2, and an axial force sensor 3. An exhaust port is provided on the observation top plate 4, with a permeable stone 9 at the bottom of the exhaust port. Multiple connection holes are also provided at different locations on the observation top plate 4. A sealing ring 8 is provided at the bottom of the observation top plate 4. The permeable stone 9 and the sealing ring 8 are provided on the top of the chamber base 6, and a pipe is installed inside the chamber base 6. A switch 7 is provided at one end of the pipe, and the other end of the pipe is connected to a water inlet. The side confinement ring 5 is placed between the observation top plate 4 and the base 6. A support plate 10 is provided above the observation top plate 4, and the support plate 10 has connection holes. The laser displacement sensor 1 is located below the support plate 10 and suspended above the observation top plate 4. The radial force sensor 2 is embedded in the side confinement ring 5, and the axial force sensor 3 is located below the chamber base 6, with a connection hole. In some embodiments, the pipe inside the chamber base 6 is a concentric annular pipe. A camera is also mounted on the support plate 10.

[0039] The observation top plate 4, axial force sensor 3, and support plate 10 are fixedly connected by a connecting frame. The soil sample chamber is composed of the observation top plate 4, side limiting ring 5, and base 6, which are fixed together by the connecting frame. Due to the setting of the sealing ring 8, the observation top plate 4 and the side limiting ring 5, as well as the side limiting ring 5 and the base 6, have a tight contact, which makes the soil sample chamber have good overall sealing performance, isolating it from external gas and liquid, avoiding interference from external non-experimental control factors, and enabling precise control of the experiment.

[0040] The connecting frame includes bolts, hexagonal nuts, and cap nuts. Bolts pass through the connecting holes of the support plate 10, the observation top plate 4, and the axial force sensor 3. Cap nuts are installed at the top of the connecting holes of the support plate 10, and hexagonal nuts are installed at the bottom. Cap nuts are installed at the top of the connecting holes of the observation top plate 4. Hexagonal nuts are installed at the bottom of the connecting holes of the axial force sensor 3.

[0041] The water injection system includes a pressure and volume controller 11 and a water injection system connection switch 7. The pressure and volume controller 11 is connected to the switch 7 via a pipe.

[0042] In some embodiments, the side confining ring 5 is a square ring, and the permeable stone 9 is a square permeable stone corresponding to the side confining ring 5; in this case, the water inlet is the permeable stone 9. In other embodiments, the side confining ring 5 is a side confining ring with water inlet channels on its side, and the permeable stone 9 is a water-impermeable material of the same size as the side confining ring 5; in this case, the water inlet is the side confining ring 5. Therefore, the overall test device is detachable, facilitating the replacement and improvement of each component. The side confining ring 5 can be a set of replaceable components of various shapes, such as circular or rectangular, or it can have water inlet channels on its side as a water inlet.

[0043] The suction control system connects to switch 7 and the exhaust port. The porous air bottle 13 is connected to filter bottle 12 and gas circulation pump 14 via conduits. Filter bottle 12 is connected to the inlet pipe, which is connected to switch 7. Gas circulation pump 14 is connected to the exhaust port of observation top plate 4 via an exhaust pipe. Both porous air bottle 13 and filter bottle 12 include long and short pipes. The long pipe of porous air bottle 13 is connected to gas circulation pump 14 via a conduit, and the short pipe of porous air bottle 13 is connected to the long pipe of filter bottle 12 via a conduit. The short pipe of filter bottle 12 is connected to switch 7. The short pipe of filter bottle 12 is the inlet pipe.

[0044] Using the above-mentioned test apparatus, joint expansion tests and wet-dry cycle tests can be conducted to obtain the mechanical and displacement parameters of the soil during the change process.

[0045] 1. Joint Expansion Test

[0046] In this experiment, the test material was bentonite. First, the axial force sensor 3, side confinement ring 5, base 6, bolts, and cap nuts were installed accordingly, and switch 7 was turned off. A bentonite sample with a diameter smaller than that of the side confinement ring 5 was placed into the side confinement ring 5, creating a gap to simulate the joints in a deep geological treatment chamber. After proper installation, the observation top plate 4 was placed on top of the side confinement ring 5, and hexagonal nuts were installed and tightened to ensure the airtightness of the soil sample chamber. The support plate 10 was connected to the bolts, and after adjusting the support plate 10 to a suitable height, nuts and laser displacement sensor 1 were installed. The camera was installed into the camera lens pre-drilled hole on the support plate 10. The water injection system contained chemical solutions such as deionized water, HCl acid solution, NaOH alkali solution, and NaCl salt solution. Switch 7, which connected the water injection system to the main structure, was turned on, and the pressure-volume controller 11 was set to a certain water pressure, allowing the chemical solution to flow into the pipes inside the chamber base 6, then into the water inlet, and through the water inlet, into the soil sample. The solution continuously flowed through the soil sample chamber to expel internal gases. At this point, the soil sample in the soil sample chamber is stabilized and moistened. The camera on the support plate 10 can record the macroscopic changes in the soil in real time from above. At the same time, the laser displacement sensor 1 can monitor the displacement caused by the expansion of the soil sample edge. After the bentonite has filled the joint, the radial and axial expansion forces begin to develop, and the radial force sensor 2 and the axial force sensor 3 can monitor the expansion force values.

[0047] In addition, different side-confining rings 5 ​​and permeable stones 9 can be used to investigate the effects of sample shape and solution contact method on the expansion performance of bentonite. By replacing the side-confining ring 5 with a square ring and the permeable stone 9 with a corresponding square permeable stone, the above steps can be repeated to complete the joint expansion test of rectangular samples; or the side-confining ring 5 can be replaced with a side-confining ring 5 with water inlet channels on the side, and the permeable stone 9 can be replaced with an impermeable material of the same size. After closing the switch 7, the pressure volume controller 11 is connected to the channel of the side-confining ring 5, and the above steps can be repeated to complete the joint expansion test with lateral water inlet.

[0048] 2. Wet and dry cycle test

[0049] The wet-dry cycle test targets soil and rock masses that undergo macroscopic changes under wet-dry cycles, such as cohesive soil that shrinks and cracks when dry, and expansive soil and expansive rock that expand and contract due to changes in water content. First, the axial force sensor 3, side confinement ring 5, base 6, bolts, and cap nuts are properly installed. Then, the prepared soil sample is placed inside the side confinement ring 5. After aligning each connection hole and bolt on the observation top plate 4, the observation top plate 4 is placed on the side confinement ring 5, and hexagonal nuts are installed and tightened to ensure the airtightness of the soil sample chamber 1. The support plate 10 is connected to the bolts, and after adjusting the support plate 10 to a suitable height, the nuts and laser displacement sensor are installed. A camera is mounted on the support plate 10.

[0050] During the humidification test, the pressure-volume controller 11 injects solution into the soil sample chamber. After the humidification test is completed, the switch 7 is turned off, the pipe between the switch 7 and the pressure-volume controller 11 is removed, and the pipe between the switch 7 and the suction control system 12 is reconnected for the drying test. Depending on the suction value control requirements, different saturated salt solutions or acid solutions of different concentrations, such as NaCl, KCl, K2CO3, HCl, H2SO4, etc., are placed in the porous air bottle 13. The long tube of the porous air bottle 13 is connected to the gas circulation pump 14 through a conduit, and the short tube of the porous air bottle 13 is connected to the long tube of the filter bottle 12 through a conduit. The short tube of the filter bottle 12 is then connected to the switch 7 through an air inlet pipe. The other port of the gas circulation pump 14 is connected to the exhaust port of the observation top plate 4. The suction force of the soil sample in the soil sample chamber gradually balances with the suction value in the suction control system 12 until the drying test is completed.

[0051] Alternating wet and dry tests allow for real-time observation of the macroscopic changes in the soil from above the observation plate 3. A camera on the support plate 10 records these macroscopic changes in real-time from above. Simultaneously, the laser displacement sensor 1 monitors the morphology and displacement of cracks on the soil sample surface. Radial force sensors 2 and axial force sensors 3 monitor stress changes in the radial direction and along the axial direction of the sensors.

[0052] This invention realizes the drying, wetting, and wet-drying cycles of soil, and visualizes the macroscopic manifestation of soil suction changes, overcoming the shortcomings of the invisible soil suction changes in conventional tests. It provides the possibility of qualitative description and analysis, and at the same time, it measures mechanical and displacement parameters during soil changes, providing quantitative parameters. The comprehensive analysis of qualitative and quantitative results provides important information parameters for soil morphology development characteristics and physical quantities, which can be used in geological engineering, geotechnical engineering and other related fields.

[0053] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A suction-controlled soil deformation observation and measurement device, characterized in that, This includes the main structure, water injection system, and suction control system, among which, The main structure includes an observation top plate (4), a side confinement ring (5), a chamber base (6), a connecting frame, and three sensors, including a laser displacement sensor (1), a radial force sensor (2), and an axial force sensor (3). An exhaust port is provided on the top plate (4), and a permeable stone (9) is provided at the bottom of the exhaust port. A connection hole is opened in the top plate (4), and a sealing ring (8) is provided at the bottom of the top plate (4). A permeable stone (9) and a sealing ring (8) are installed on the top of the chamber base (6). A pipe is installed inside the chamber base (6). A switch (7) is installed at one end of the pipe, and the other end of the pipe is connected to a water inlet. The lateral confinement ring (5) is placed between the observation top plate (4) and the base (6). A support plate (10) is provided above the observation top plate (4). The laser displacement sensor (1) is located at the lower part of the support plate (10) and suspended above the observation top plate (4). A connection hole is opened on the support plate (10), and a camera is mounted on the support plate (10). The radial force sensor (2) is embedded in the side limiting ring (5). An axial force sensor (3) is located under the chamber base (6), and a connection hole is provided on the axial force sensor (3). The observation top plate (4), axial force sensor (3) and support plate (10) are fixedly connected by a connecting frame. The observation top plate (4), side limiting ring (5) and base (6) constitute the soil sample chamber. The water injection system includes a pressure and volume controller (11) and a water injection system connection switch (7). The suction control system includes a porous air bottle (13), a filter bottle (12) and a gas circulation pump (14), and the suction control system is connected to a switch (7) and an exhaust port.

2. The suction-controlled soil deformation observation and measurement device according to claim 1, characterized in that, The multi-hole ventilation bottle (13) is connected to the filter bottle (12) and the gas circulation pump (14) respectively through the conduit. The filter bottle is connected to the air inlet pipe of (12), the air inlet pipe is connected to the switch (7), and the gas circulation pump (14) is connected to the exhaust port of the observation top plate (4) through the exhaust pipe.

3. The suction-controlled soil deformation observation and measurement device according to claim 2, characterized in that, Both the porous gas cylinder (13) and the filter bottle (12) include a long tube and a short tube. The long tube of the porous gas cylinder (13) is connected to the gas circulation pump (14) through a conduit. The short tube of the porous gas cylinder (13) is connected to the long tube of the filter bottle (12) through a conduit. The short tube of the filter bottle (12) is connected to the switch (7). The short tube of the filter bottle (12) is the air inlet tube.

4. The suction-controlled soil deformation observation and measurement device according to claim 1, characterized in that, The side confinement ring (5) is a square ring, the permeable stone (9) is a square permeable stone corresponding to the side confinement ring (5), and the water inlet is a permeable stone (9).

5. The suction-controlled soil deformation observation and measurement device according to claim 1, characterized in that, The side limiting ring (5) is a side limiting ring with a water inlet channel on the side. The permeable stone (9) is made of impermeable material of the same size as the side limiting ring (5). The water inlet is the side limiting ring (5).

6. The suction-controlled soil deformation observation and measurement device according to claim 1, characterized in that, The connecting frame includes bolts, hexagonal nuts, and cap nuts.

7. The suction-controlled soil deformation observation and measurement device according to claim 6, characterized in that, Bolts pass through the connection holes of the support plate (10), the observation top plate (4), and the axial force sensor (3).

8. The suction-controlled soil deformation observation and measurement device according to claim 7, characterized in that, A cap nut is installed on the top of the connection hole of the bracket plate (10), and a hexagonal nut is installed on the bottom.

9. A suction-controlled soil deformation observation and measurement device according to claim 7, characterized in that, A cap nut is installed on the top of the connection hole of the observation top plate (4).

10. A suction-controlled soil deformation observation and measurement device according to claim 7, characterized in that, A hexagonal nut is installed at the bottom of the connection hole of the axial force sensor (3).

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