One-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measuring device and use method

Abstract

The invention belongs to the technical field of geotechnical engineering data measuring equipment, and particularly relates to a one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measuring device which comprises a soil column sample chamber, the soil column sample chamber is installed on a supporting structure, and monitoring systems are located on the two sides of the soil column sample chamber. The water supply system and the drainage system are located at the upper end and the lower end of the soil column sample chamber respectively, the loading system is located at the top of the supporting structure and acts on the upper portion of the soil column sample chamber, and the data acquisition system is connected with the loading system, the water supply system, the drainage system and the monitoring system; the water supply system and the drainage system are matched to detect the permeability of soil and dynamic change of expansibility of expansive soil in the permeation process, meanwhile, the monitoring system is used for detecting the deformation conditions of different depth positions in a soil column, then the data acquisition system is used for real-time detection and recording, and the device is simple in structure, high in experiment efficiency and high in practicability. The result observation is obvious, the accuracy is high and the manufacturing cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of geotechnical engineering data measurement equipment, and in particular relates to a one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device and a use method. Background Art

[0002] The permeability and swelling properties of expansive soil will change dynamically during the infiltration process. Therefore, studying the swelling changes and water migration of the soil during the infiltration process, as well as exploring the critical swelling depth of the soil, is particularly important for predicting the moisture content changes and swelling potential of actual projects.

[0003] The traditional unsaturated permeability test of soil columns can only obtain the overall deformation of the top of the soil column. It is difficult to measure the deformation at different depths inside the soil column, and it is impossible to establish the relationship between the deformation of key points on the surface of the soil column and the initial state of the soil. It is also impossible to conduct detailed observation and analysis on the permeability-expansion law and swelling phenomenon of expansive soil. Summary of the invention

[0004] The purpose of the present invention is to provide a one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device and a use method, which can realize the unsaturated permeability test of simulated expansive soil in a one-dimensional state, and can measure the permeability coefficient and deformation law of the soil sample during the wetting process.

[0005] In order to meet the above purpose, the technical solution adopted by the present invention is: A one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measuring device comprises a soil column sample chamber, a supporting structure, a loading system, a water supply system, a drainage system, a monitoring system and a data acquisition system, wherein the soil column sample chamber is installed on the supporting structure, the monitoring system is located on both sides of the soil column sample chamber, the water supply system and the drainage system are respectively located at the upper end and the lower end of the soil column sample chamber, the loading system is located on the top of the supporting structure, the loading system acts on the top of the soil column sample chamber, and the data acquisition system is connected with the loading system, the water supply system, the drainage system and the monitoring system.

[0006] Preferably, the soil column sample chamber comprises an organic glass barrel, a soil column is arranged in the organic glass barrel, a plurality of targets are arranged on the soil column in sequence, moisture sensors are arranged on both sides of the soil column, filter paper and permeable stone are arranged on the top and bottom of the soil column in sequence, a water accumulation area is arranged from the permeable stone at the top of the soil column to the top of the organic glass barrel, a permeable bottom plate is arranged below the permeable stone at the bottom of the soil column, the permeable bottom plate is provided with a drain outlet, and the organic glass barrel and the permeable bottom plate are made of acrylic material.

[0007] Preferably, the supporting structure includes four supporting rods, a top plate is provided on the top of the four supporting rods, a plurality of dial indicator brackets are provided below the top plate, a dial indicator is provided on the dial indicator bracket, a measuring head of the dial indicator acts on the upper surface of the permeable stone at the top of the soil column, a base is provided at the bottom of the four supporting rods, a base bracket is provided below the base, and the base, top plate, supporting rods and base bracket are made of stainless steel.

[0008] Preferably, the loading system includes a pneumatic pressurizing device, which is installed under the top plate of the supporting structure. A connecting rod is provided under the pneumatic pressurizing device, and a pressure sensor is provided between the pneumatic pressurizing device and the connecting rod. A loading base is provided under the connecting rod, and the loading base is located above the permeable stone at the top of the soil column. The connecting rod acts on the loading base, and both the connecting rod and the loading base are made of stainless steel that is not easy to corrode.

[0009] Preferably, the water supply system includes a water supply device, a pedestal is provided below the water supply device, a weighing sensor is provided between the pedestal and the water supply device, a water inlet pipe is provided on one side of the water supply device, the other end of the water inlet pipe is connected to the water accumulation area at the top of the soil column, a water inlet control valve is provided on the water inlet pipe, the pedestal below the water supply device is movably mounted on two adjacent support frames, and the water supply device is a Martens flask.

[0010] Preferably, the drainage system includes a drainage device, a pedestal is provided below the drainage device, a weighing sensor is provided between the drainage device and the pedestal, a drainage pipe is provided on one side of the drainage device, the other end of the drainage pipe is connected to the drainage outlet of the permeable bottom plate, a drainage control valve is provided on the drainage pipe, and the pedestal below the drainage device is placed on the ground.

[0011] Preferably, the monitoring system comprises a monitoring camera, which is mounted on a movable bracket, on which a height adjuster is provided, and the monitoring camera acts on a target on the soil column.

[0012] Preferably, the data acquisition system includes a multifunctional data acquisition instrument, which is connected to the moisture sensor, the dial indicator, the pressure sensor and the weighing sensor signals, and is provided with a PC for displaying and storing data.

[0013] Preferably, the loading base is a circular structure, the central position of the loading base is the base center, the loading base is surrounded by a base outer ring, a plurality of base brackets are provided between the base center and the base outer ring, and the connecting rod acts on the base center.

[0014] Preferably, the method for using the one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device comprises the following steps: A. Put the soil with a certain moisture content into the organic glass barrel and compact it layer by layer to form a soil column. Set filter paper and permeable stone above and below the soil column, and bury the moisture sensor and target at a certain height of the soil column. B. Install a loading base on the permeable stone above the prepared soil column, and install a pneumatic pressurizing device and a connecting rod under the top plate of the supporting structure. The connecting rod acts on the loading base. A dial gauge is installed under the top plate using a dial gauge bracket. The dial gauge acts on the permeable stone above the soil column. C. A pressure sensor is installed between the connecting rods and the pneumatic pressurizing device placed in sequence above the loading base, and an overburden load with different target pressures is applied to the soil column by adjusting the pneumatic pressurizing device.

[0015] D. Turn on the monitoring camera to select the optimal marking surface and target fitting for the target inside the soil column; E. Adjust the position of the pedestal under the water supply device, determine the water depth in the water accumulation area, open the water inlet control valve and the drainage control valve, and carry out a one-dimensional unsaturated permeability test.

[0016] F. At the beginning of the infiltration test, turn on the multifunctional data acquisition instrument in the data acquisition system to display and collect data from the moisture sensor, dial indicator, pressure sensor and weighing sensor.

[0017] G. The moisture sensor data is calculated using the transient profile method to establish the correlation between the deformation of key points on the soil column surface and the initial state of the soil.

[0018] The beneficial effects of the present invention are: (1) The present invention installs a soil column in a plexiglass barrel, and then sets filter paper and permeable stone at both ends, and uses the cooperation between the water supply system and the drainage system to detect the dynamic changes in the permeability and expansion of the soil during the infiltration process. At the same time, the monitoring system is used to detect the deformation of different depths inside the soil column, and then the data acquisition system is used to detect and record in real time, so as to observe and analyze the permeability-expansion law and swelling phenomenon of the expansive soil in detail. The present invention has a simple structure, high experimental efficiency, obvious observation results and high accuracy, and low manufacturing cost.

[0019] (2) The loading base in the present invention is a circular structure, and the center position of the loading base is the base center. The base outer ring around the base center is connected to the base outer ring through the base bracket, so that the force is transmitted evenly and the water can penetrate evenly.

[0020] (3) The monitoring of the internal deformation of the soil column of the present invention is mainly achieved through a monitoring system. The monitoring system sets the monitoring camera on the target of the corresponding monitoring point of the soil column by using a movable bracket and a height adjuster. The left and right positions can be adjusted by the movable bracket, and the height position can be adjusted by the height adjuster. That is, a single camera device can detect the deformation of different positions of the soil column. When the soil column is infiltrated, the development law of the deformation of the cross-section of the soil column at different depths with the infiltration time can be obtained through the digital close-range photography technology of the monitoring camera, and the correlation between the deformation of the key points on the surface of the soil column and the initial state of the soil can be established. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a schematic diagram of the structure of the loading base; Figure 3 This is the deformation analysis flow chart; In the figure: 1. Organic glass barrel; 2. Permeable bottom plate; 3. Target; 4. Base; 5. Soil column; 6. Moisture sensor; 7. Permeable stone; 8. Connecting rod; 9. Dial indicator; 10. Pressure sensor; 11. Dial indicator bracket; 12. Pneumatic pressurizing device; 13. Top plate; 14. Support rod; 15. Water supply device; 16. Weighing sensor; 17. Drainage device; 18. Pedestal; 19. Monitoring camera; 20. Movable bracket; 21. Water inlet pipe; 22. Drainage pipe; 23. Base bracket; 24. Water inlet control valve; 25. Drainage control valve; 26. Height regulator; 27. Multi-function data acquisition instrument; 28. PC; 29. ​​Filter paper; 30. Loading base; 31. Base center; 32. Base bracket; 33. Base outer ring. DETAILED DESCRIPTION

[0023] The invention is further described below in conjunction with the accompanying drawings, specific implementation methods and analysis principles: like Figure 1 and 2 The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measuring device shown in the figure includes a soil column sample chamber, a supporting structure, a loading system, a water supply system, a drainage system, a monitoring system and a data acquisition system. The soil column sample chamber is installed on the supporting structure, the monitoring system is located on both sides of the soil column sample chamber, the water supply system and the drainage system are located at the upper and lower ends of the soil column sample chamber respectively, the loading system is located on the top of the supporting structure, the loading system acts on the top of the soil column sample chamber, and the data acquisition system is connected to the loading system, the water supply system, the drainage system and the monitoring system.

[0024] The soil column sample chamber includes an organic glass barrel 1, in which a soil column 5 is arranged, and a plurality of targets 3 are arranged on the soil column 5 in sequence. Moisture sensors 6 are arranged on both sides of the soil column 5, and a plurality of moisture sensors 6 are arranged from high to low from the soil column 5, so as to detect the moisture of soil columns at different depths. Filter paper 29 and permeable stone 7 are arranged on the top and bottom of the soil column 5 in sequence, respectively. A water accumulation area is arranged from the permeable stone 7 at the top of the soil column 5 to the top of the organic glass barrel 1, and a permeable bottom plate 2 is arranged below the permeable stone 7 at the bottom of the soil column 5. The permeable bottom plate 2 is provided with a drainage port, and the organic glass barrel 1 and the permeable bottom plate 2 are made of acrylic material.

[0025] The supporting structure includes four supporting rods 14, a top plate 13 is provided on the top of the four supporting rods 14, a plurality of dial indicator brackets 11 are provided below the top plate 13, a dial indicator 9 is provided on the dial indicator bracket 11, and the measuring head of the dial indicator 9 acts on the upper surface of the permeable stone 7 at the top of the soil column 5, a base 4 is provided at the bottom of the four supporting rods 14, and a base bracket 23 is provided below the base 4. The base 4, the top plate 13, the supporting rods 14 and the base bracket 23 are made of stainless steel, and the components between the supporting structures are connected and fixed by bolts to facilitate the disassembly and installation of the device.

[0026] The loading system includes a pneumatic pressurizing device 12, which is installed below the top plate 13 of the supporting structure. A connecting rod 8 is provided below the pneumatic pressurizing device 12. A pressure sensor 10 is provided between the pneumatic pressurizing device 12 and the connecting rod 8. A loading base 30 is provided below the connecting rod 8. The loading base 30 is located above the permeable stone 7 at the top of the soil column 5. The connecting rod 8 acts on the loading base 30. Both the connecting rod 8 and the loading base 30 are made of stainless steel that is not easy to corrode. The loading base 30 is a circular structure, so that the force is transmitted evenly and the water can infiltrate evenly. The center position of the loading base 30 is the base center 31, and the surrounding of the loading base 30 is the base outer ring 33. A number of base brackets 32 are provided between the base center 31 and the base outer ring 33, and the connecting rod 8 acts on the base center 31.

[0027] The water supply system includes a water supply device 15, a pedestal 18 is provided below the water supply device 15, a weighing sensor 16 is provided between the pedestal 18 and the water supply device 15, and the amount of water in the weighing water supply device is detected in real time. A water inlet pipe 21 is provided on one side of the water supply device 15, and the other end of the water inlet pipe 21 is connected to the water accumulation area at the top of the soil column 5. A water inlet control valve 24 is provided on the water inlet pipe 21 to control the water inlet of the water inlet pipe 21. The pedestal 18 below the water supply device 15 is movably installed on two adjacent support frames 14, and its purpose is to be able to adjust the height of the water supply device 15 at will to control the depth of the water in the water accumulation area. The water supply device 15 is a Marsh flask.

[0028] The drainage system includes a drainage device 17, a base 18 is provided below the drainage device 17, a weighing sensor 16 is provided between the drainage device 17 and the base 18, and is used to measure the amount of water collected by the drainage device 17, a drainage pipe 22 is provided on one side of the drainage device 17, and the other end of the drainage pipe 22 is connected to the drainage port of the permeable bottom plate 2, and a drainage control valve 25 is provided on the drainage pipe 22, which is used to control the water flow in the drainage pipe 22 on the drainage device 17, and the base 18 below the drainage device 17 is placed on the ground.

[0029] The monitoring system includes a monitoring camera 19 , which is mounted on a movable bracket 20 . The movable bracket 20 is provided with a height adjuster 26 . The monitoring camera 19 acts on the target 3 on the soil column 5 .

[0030] The data acquisition system includes a multifunctional data acquisition instrument 27, which is an EM50 data acquisition instrument produced by DECAGON. The multifunctional data acquisition instrument 27 is connected to the moisture sensor 6, the dial indicator 9, the pressure sensor 10 and the weighing sensor 16. The multifunctional data acquisition instrument 27 is used to collect detection data from the moisture sensor 6, the dial indicator 9, the pressure sensor 10 and the weighing sensor 16. The multifunctional data acquisition instrument 27 is provided with a PC 28, which is used to display and store data.

[0031] The monitoring of the internal deformation of the soil column 5 is mainly achieved through the monitoring system. The monitoring system adopts a digital close-range photogrammetry system (DPS), which mainly consists of a monitoring camera 19, a movable bracket 20, a height adjuster 26 and a target 3. The data detected by the monitoring system is transmitted to the data acquisition system through signal connection transmission. The monitoring deformation analysis in the monitoring digital image includes: optimal marker surface selection, image acquisition and target fitting, structural feature point information extraction and displacement calculation. The deformation analysis process is as follows: Figure 3 .

[0032] The unsaturated permeability coefficient of the soil column 5 is mainly monitored and collected by the pre-buried moisture sensor 6, and is calculated by the transient profile method. The transient profile method measures the time and space profiles of the moisture content of each section under the seepage state of the one-dimensional soil column, performs differential calculations on the soil columns with different sections, and obtains the unsaturated permeability coefficient by calculation.

[0033] A method for using a one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device comprises the following steps: A. The soil with a pre-set moisture content is layered and compacted into a plexiglass barrel 1 to form a soil column 5, and filter paper 29 and permeable stone 7 are arranged above and below the soil column 5, and a moisture sensor 6 and a target 3 are buried at a certain height of the soil column 5; B. Install a loading base 30 on the permeable stone 7 above the prepared soil column 5, and install a pneumatic pressurizing device 12 and a connecting rod 8 below the top plate 13 of the supporting structure. The connecting rod 8 acts on the loading base 30. A dial gauge 9 is installed under the top plate 13 using a dial gauge bracket 11. The dial gauge acts on the permeable stone 7 above the soil column 5. C. A pressure sensor 10 is installed between the connecting rod 8 and the pneumatic pressurizing device 12 placed sequentially above the loading base 30 , and an overburden load with different target pressures is applied to the soil column 5 by adjusting the pneumatic pressurizing device 12 .

[0034] D. Turn on the monitoring camera 19 to select the optimal marking surface and fit the target 3 inside the soil column 5; E. Adjust the position of the pedestal 18 below the water supply device 15, determine the water depth in the water accumulation area, open the water inlet control valve 24 and the drainage control valve 25, and carry out a one-dimensional unsaturated permeability test.

[0035] F. When the infiltration test starts, the multifunctional data acquisition instrument 27 in the data acquisition system is turned on to display and acquire the data of the moisture sensor 6, the dial indicator 9, the pressure sensor 10 and the weighing sensor 16.

[0036] G. The data of the moisture sensor 6 is calculated using the transient profile method to establish the correlation between the deformation of the key points on the surface of the soil column 5 and the initial state of the soil.

Claims

1. A one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device, characterized in that: It includes a soil column sample chamber, a supporting structure, a loading system, a water supply system, a drainage system, a monitoring system and a data acquisition system. The soil column sample chamber is installed on the supporting structure, the monitoring system is located on both sides of the soil column sample chamber, the water supply system and the drainage system are respectively located at the upper end and the lower end of the soil column sample chamber, the loading system is located on the top of the supporting structure, the loading system acts on the top of the soil column sample chamber, and the data acquisition system is connected with the loading system, the water supply system, the drainage system and the monitoring system.

2. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized in that: The soil column sample chamber comprises an organic glass barrel (1), a soil column (5) is arranged in the organic glass barrel (1), a plurality of targets (3) are arranged on the soil column (5), moisture sensors (6) are arranged on both sides of the soil column (5), filter paper (29) and permeable stone (7) are arranged on the top and bottom of the soil column (5), respectively, a water accumulation area is arranged from the permeable stone (7) at the top of the soil column (5) to the top of the organic glass barrel (1), a permeable bottom plate (2) is arranged below the permeable stone (7) at the bottom of the soil column (5), and the permeable bottom plate (2) is provided with a drainage port, and the organic glass barrel (1) and the permeable bottom plate (2) are made of acrylic material.

3. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized in that: The support structure comprises four support rods (14), a top plate (13) is provided on the top of the four support rods (14), a plurality of dial gauge brackets (11) are provided below the top plate (13), a dial gauge (9) is provided on the dial gauge bracket (11), a measuring head of the dial gauge (9) acts on the upper surface of the permeable stone (7) at the top of the soil column (5), a base (4) is provided at the bottom of the four support rods (14), a base bracket (23) is provided below the base (4), and the base (4), the top plate (13), the support rods (14) and the base bracket (23) are made of stainless steel.

4. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized in that: The loading system comprises a pneumatic pressurizing device (12), the pneumatic pressurizing device (12) being installed below a top plate (13) of a supporting structure, a connecting rod (8) being provided below the pneumatic pressurizing device (12), a pressure sensor (10) being provided between the pneumatic pressurizing device (12) and the connecting rod (8), a loading base (30) being provided below the connecting rod (8), the loading base (30) being located above a permeable stone (7) at the top of a soil column (5), the connecting rod (8) acting on the loading base (30), and the connecting rod (8) and the loading base (30) being both made of non-corrosive stainless steel.

5. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized in that: The water supply system comprises a water supply device (15), a pedestal (18) is provided below the water supply device (15), a weighing sensor (16) is provided between the pedestal (18) and the water supply device (15), a water inlet pipe (21) is provided on one side of the water supply device (15), the other end of the water inlet pipe (21) is connected to a water accumulation area at the top of the soil column (5), a water inlet control valve (24) is provided on the water inlet pipe (21), the pedestal (18) below the water supply device (15) is movably mounted on two adjacent support frames (14), and the water supply device (15) is a Martens flask.

6. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized by: The drainage system comprises a drainage device (17), a pedestal (18) is provided below the drainage device (17), a weighing sensor (16) is provided between the drainage device (17) and the pedestal (18), a drainage pipe (22) is provided on one side of the drainage device (17), the other end of the drainage pipe (22) is connected to a drainage port of a water-permeable bottom plate (2), a drainage control valve (25) is provided on the drainage pipe (22), and the pedestal (18) below the drainage device (17) is placed on the ground.

7. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized by: The monitoring system comprises a monitoring camera (19), wherein the monitoring camera (19) is mounted on a movable bracket (20), wherein a height adjuster (26) is provided on the movable bracket (20), and the monitoring camera (19) acts on a target (3) on a soil column (5).

8. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized by: The data acquisition system comprises a multifunctional data acquisition instrument (27), wherein the multifunctional data acquisition instrument (27) is connected to a moisture sensor (6), a dial indicator (9), a pressure sensor (10) and a weighing sensor (16) by signals, and a PC (28) is provided on the multifunctional data acquisition instrument (27), wherein the PC (28) is used for displaying and storing data.

9. The one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 4 is characterized in that: The loading base (30) is a circular structure. The central position of the loading base (30) is the base center (31). The loading base (30) is surrounded by a base outer ring (33). A plurality of base brackets (32) are provided between the base center (31) and the base outer ring (33). The connecting rod (8) acts on the base center (31).

10. The method for using the one-dimensional soil column multi-point deformation monitoring and unsaturated permeability coefficient measurement device according to claim 1 is characterized in that The following steps are involved: A. A soil body with a pre-set moisture content is compacted and placed in layers in a plexiglass barrel (1) to form a soil column (5), and filter paper (29) and permeable stone (7) are arranged above and below the soil column (5), and a moisture sensor (6) and a target (3) are buried at a certain height of the soil column (5); B. Installing a loading base (30) on the permeable stone (7) above the prepared soil column (5), and installing a pneumatic pressurizing device (12) and a connecting rod (8) below the top plate (13) of the supporting structure, wherein the connecting rod (8) acts on the loading base (30), and a dial indicator (9) is installed below the top plate (13) using a dial indicator bracket (11), and the dial indicator acts on the permeable stone (7) above the soil column (5); C. A pressure sensor (10) is installed between the connecting rods (8) and the pneumatic pressurizing device (12) placed sequentially above the loading base (30), and an overburden load with different target pressures is applied to the soil column (5) by adjusting the pneumatic pressurizing device (12); D. Turn on the monitoring camera (19) to select the optimal marking surface and perform target fitting on the target (3) inside the soil column (5); E. Adjust the position of the pedestal (18) below the water supply device (15), determine the water depth in the water accumulation area, open the water inlet control valve (24) and the water discharge control valve (25), and conduct a one-dimensional unsaturated permeability test; F. When the infiltration test starts, the multifunctional data acquisition device (27) in the data acquisition system is turned on to display and acquire data from the moisture sensor (6), the dial indicator (9), the pressure sensor (10) and the weighing sensor (16); G. The data from the moisture sensor (6) is calculated using the transient profile method to establish the correlation between the deformation of key points on the surface of the soil column (5) and the initial state of the soil.

Images