A kind of infiltration test device and test method of loess with developed joints

Abstract

The invention discloses an infiltration test device and a test method for a loess body with developed joints. The device includes an infiltration main device, an opening measurement system, a rainfall system, a water flow collection system and a moisture field test system; the opening measurement system is connected to the infiltration main device, the rainfall system and the water flow collection system are respectively connected to the infiltration main device, and the moisture field test system is connected to the infiltration main device; two soil samples are built into the infiltration main device, one soil sample is fixed, and the opening of the loess body with developed joints is measured by adjusting the movement of the other soil sample; the loess joint opening part is connected through the rainfall system to test the infiltration of rainwater on the loess body with developed joints. The invention quantitatively measures the influence of the opening on the change process of the infiltration moisture field of the loess body with developed joints while trying not to disturb the initial structural state of the soil body.

Description

Technical Field

[0001] The invention belongs to the technical field of rock and soil model test equipment, and discloses a test device for infiltration of a loess body with developed joints and a test method for the dynamic evolution of an infiltration water field. Background Art

[0002] Loess joints are widely developed in loess. Loess joints are the dominant channels for water infiltration. When rainfall infiltrates, due to the existence of matrix suction in the loess with developed joints, the water content in the soil changes and migrates. The change in water content causes changes in the structure and properties of the soil. In severe cases, it can cause collapsing deformation, directly causing damage to the foundation, and further changing the properties of the soil. This cycle will seriously affect the construction of roadbed projects, water conservancy projects, and municipal projects. These projects all involve the dynamic change of water content in loess with developed joints. Therefore, conducting experiments on the infiltration of loess with developed joints and studying the dynamic change of the water field during the infiltration of loess with developed joints has important research significance for guiding actual engineering construction.

[0003] At present, the method for testing the dynamic moisture content and moisture field distribution state of jointed loess is to set up multiple groups of control tests, conduct infiltration tests under the same test conditions, disassemble a group of molds at regular intervals, dig holes at the corresponding test node positions to take soil, and use microwave oven drying method to test the mass moisture content, and finally sort out all time nodes for dynamic evolution analysis of the moisture field of jointed loess. The experimental workload of this method is huge, and the drying method has limited nodes to measure each time when testing the moisture content, while the moisture content distribution state of the moisture field is ever-changing, and the test time interval requirements are extremely strict. It cannot be guaranteed that each sample node is at the same test time, and the error is large. Summary of the invention

[0004] In order to solve the above-mentioned defects in the prior art research, the purpose of the present invention is to provide a test device for infiltration of loess with developed joints and a test method for the dynamic evolution of the infiltration water field. The method simulates the water infiltration process of loess with developed open joints under continuous rainfall conditions under the most unfavorable working conditions as much as possible, and can realize the dynamic real-time measurement of the water content distribution field during the infiltration process, and quantitatively measure the influence of the opening degree on the change process of the infiltration water field of loess with developed joints while trying not to disturb the initial structural state of the soil body. The device is easy to disassemble, the infiltration device is not easy to deform, and the materials used are environmentally friendly and economical.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions.

[0006] An infiltration test device for a loess body with developed joints comprises an infiltration main device, an opening measurement system, a rainfall system, a water flow collection system and a moisture field test system; the opening measurement system is connected to the infiltration main device, the rainfall system and the water flow collection system are respectively connected to the infiltration main device, and the moisture field test system is connected to the infiltration main device;

[0007] Two soil samples are built into the main infiltration device, and the two soil samples are separated by the open part of loess joints. The rainfall system is facing the open part of loess joints. One of the soil samples is fixed, and the other soil sample is placed on a movable trolley. By adjusting the movement of the other soil sample, the opening degree of the loess body with developed joints is measured. The open part of the loess joints is connected through the rainfall system to test the infiltration of rainwater into the loess body with developed joints.

[0008] For the above technical solution, a further preferred solution of the present invention is:

[0009] Preferably, the two soil samples include a first soil sample and a second soil sample, the first soil sample is arranged on a fixed-height base, and the second soil sample is arranged on a movable trolley; the fixed-height support and the bottom plane of the movable trolley are at the same height.

[0010] Preferably, the opening measurement system includes a nut horizontally arranged on the infiltration main device and a dial indicator connected to the second soil sample box, and the position of the movable trolley is changed by rotating the nut to drive the dial indicator to move and measure the opening of the second soil sample.

[0011] Preferably, the rainfall system includes a water storage tank, a water pipe and a rainfall trough, and the water storage tank is connected to the rainfall trough to the open part of the loess joint between the first soil sample and the second soil sample through the water pipe.

[0012] Preferably, the water collection system includes a guide pipe and a water collection bucket, and the guide pipe is connected to the bottom of the rain gutter side wall at 1 / 4 of the height.

[0013] Preferably, the middle part of the bottom surface of the rainfall trough is hollowed out, the width of the rainfall trough is the same as the width of the two soil samples, and the hollowing width is the same as the width of the two soil samples.

[0014] Preferably, vaseline is used to seal the gaps between the rainfall trough and the first soil sample and the second soil sample.

[0015] Preferably, the moisture field testing system includes a moisture sensor, a data analysis and acquisition instrument, and a computer. The moisture sensor is arranged in the first soil sample and the second soil sample. The moisture sensor is fixed by a rubber plug opened in a glass panel of the infiltration main device. The moisture sensor is connected to the data analysis and acquisition instrument and the computer in turn.

[0016] The present invention further provides a test method for infiltration of a loess body with developed joints using the device, comprising the following steps:

[0017] 1) Place a piece of soil on the movable trolley and the fixed support respectively, with the two pieces of soil close together with no gap in the middle, and apply vaseline on the remaining surfaces except the close surfaces;

[0018] 2) Turn the movable nut to adjust the distance between the two soil bodies, and drive the dial indicator to move and measure the opening of the loess body with developed joints;

[0019] 3) Turn on the rainfall system, read the volumetric moisture content data at different positions of the soil sample during the infiltration process through the data analysis and acquisition instrument, calculate the mass moisture content of the measured soil by computer, obtain the moisture change during the infiltration process, and complete the test of the dynamic evolution of the moisture field of the loess with developed joints during the infiltration process.

[0020] The present invention adopts the method of indoor simulation test to better simulate the influence of the opening degree on the change of the moisture field during the infiltration of the loess body with open joints, and solves the problem that the dynamic evolution law of the moisture field during the infiltration of the loess body with joints is unclear. The water infiltration process of the loess body with open joints under the most unfavorable working condition of continuous rainfall is simulated as much as possible, and the influence of the opening degree on the change process of the moisture field of the loess body with joints is quantitatively measured while the initial structural state of the soil is not disturbed as much as possible. In order to reveal that the change of water content causes the change of soil structure and properties, it provides a basis for reducing the occurrence of natural disasters such as landslides and mud-rock flows, as well as in practical engineering construction such as roadbed engineering, water conservancy engineering and municipal engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 A schematic diagram of the structure of the device provided by the present invention;

[0023] Figure 2 It is a schematic diagram of the connection between the water storage tank and the rubber water pipe and the rain gutter and the guide pipe in the present invention;

[0024] Figure 3 It is a schematic diagram of the connection method between the fastening bolts and two tempered glass panels in the present invention.

[0025] Among them: 1-first soil sample; 2-opening; 3-rainfall trough; 4-main infiltration device; 5-loess joint opening; 6-movable trolley; 7-wheel; 8-nut; 9-dial indicator; 10-water storage tank; 11-water guide pipe; 12-flow guide pipe; 13-water collection bucket; 14-second soil sample; 15-fixed support; 16-moisture sensor; 17-data analysis and acquisition instrument; 18-computer; 19-fastening bolts. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The illustrative examples and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0027] See also Figure 1 The present invention provides an infiltration test device for loess with developed joints, including an infiltration main device 4, an opening measurement system, a rainfall system, a water flow collection system and a moisture field test system; the opening measurement system is connected to the infiltration main device 4, the rainfall system and the water flow collection system are respectively connected to the infiltration main device 4, and the moisture field test system is connected to the infiltration main device 4.

[0028] Two soil samples are built into the infiltration main device 4, and the two soil samples are separated by the loess joint opening part 5, and the rainfall system is facing the loess joint opening part 5; the first soil sample 4 is fixed, and the second soil sample 14 is placed on the movable trolley 6. By adjusting the movement of the second soil sample 14, the opening degree of the loess body with developed joints is measured; the loess joint opening part 5 is connected through the rainfall system to test the infiltration of rainwater into the loess body with developed joints.

[0029] The first soil sample 1 is set on the fixed height base 15, and the second soil sample 14 is set on the movable trolley 6; the fixed height support 15 and the bottom plane of the movable trolley 6 are at the same height. The first and second soil bodies 1 and 14, the rain trough 3, the fixed support 15, and the movable trolley 6 are fastened by fastening bolts 19 through the openings 2 on the front and rear tempered glass plates of the infiltration main device 4 to prevent them from being dislocated. The connection method of the fastening bolts and the two tempered glass plates is shown in FIG. Figure 3 shown.

[0030] Among them, the opening measurement system includes a nut 8 horizontally arranged on the infiltration main device 4 and a dial indicator 9 connected to the second soil sample 14 box. By rotating the nut 8 to change the position of the movable trolley 6, the dial indicator 9 is driven to move to measure the opening of the second soil sample 14.

[0031] The rainfall system includes a water tank 10, a water pipe 11 and a rainfall trough 3. The water tank 10 is connected to the rainfall trough 3 through the water pipe 11 to the loess joint opening 5 between the first soil sample 1 and the second soil sample 14. The middle of the bottom of the rainfall trough 3 is hollowed out. The width of the rainfall trough 3 is the same as the width of the two soil samples, and the hollow width is the same as the width of the two soil samples. An external nozzle is provided on one side 2 cm away from the bottom and connected to the drainage pipe 12. See the connection between the water tank and the rubber drainage pipe and the rainfall trough and the drainage pipe. Figure 2 shown.

[0032] The water collection system includes a guide pipe 12 and a water collection bucket 13. The guide pipe 12 is connected to the bottom of the side wall of the rainfall trough 3 at 1 / 4 of the height. The height of the water storage tank 10 should be higher than the height of the rainfall trough 3. The water storage tank 10 should continuously supply water to the rainfall trough 3 to ensure that the water level in the rainfall trough 3 is constant, and there should always be water flowing out of the water guide pipe 12. The height of the water collection bucket 13 should be lower than the height of the rainfall trough 3. Vaseline is used to block the gap between the rainfall trough 3 and the first soil sample 1 and the second soil sample 14.

[0033] The moisture field test system includes a moisture sensor 16, a data analysis and acquisition instrument 17, and a computer 18. The moisture sensor 16 is arranged in the first soil sample 1 and the second soil sample 14. The moisture sensor 16 is fixed by a rubber plug in a hole in the glass panel of the infiltration main device 4. The glass panel is provided with holes for the moisture sensor 16 at equal intervals in a square. The holes are provided with rubber plugs. The moisture sensor 16 is fixed on the rubber plug in the hole in the glass panel. The moisture sensor 16 is connected to the data analysis and acquisition instrument 17 and the computer 18 in sequence.

[0034] The present invention adopts the above-mentioned device to test the infiltration of loess with developed joints, which comprises the following steps:

[0035] 1) Prepare soil test blocks with a certain moisture content according to the geotechnical test requirements, and apply vaseline on the remaining surfaces except the infiltration joints after drying in the shade for later use;

[0036] 2) Place a soil body on each of the movable trolley and the fixed support 15, with the two soil bodies close to each other without a gap in the middle. Turn the movable nut 8 to adjust the distance between the two soil bodies and drive the dial indicator 9 to move and measure the opening degree of the loess body with developed joints;

[0037] 3) When the opening is adjusted to the appropriate selected opening, the two soil bodies sandwiched between the outer glass plate 4 and the inner glass plate 17 are fastened with the fastening bolts 8, and the opening measuring device 9 is removed;

[0038] 4) Install the rain gutter device 3, the water storage tank 10 and the water collection bucket 13;

[0039] 5) After the test begins, according to the test requirements, the water injection valve of the Martens flask and the valve of the water flow collection device are always opened, and the volumetric water content data at different positions of the soil sample during the infiltration process are read through the soil moisture analyzer display data, converted into the mass water content of the measured soil, and the reading changes of the moisture analyzer during the entire infiltration process are collected to complete the test of the dynamic evolution of the moisture field of the jointed loess during the infiltration process;

[0040] 6) After the test is completed, first close the Malchow flask water supply device, rotate and close the valve of the water collection device, remove the rainfall trough 3, the water storage tank 10, the water collection device 13 in turn, disassemble the main infiltration device body, clean it and set it aside.

[0041] The device of the present invention can measure the water content distribution state of each point in the infiltration water field of homogeneous loess or loess with developed joints under continuous rainfall infiltration. Through further conversion, the dynamic evolution law of the water field during the infiltration process can be obtained. Further analysis of the change in water content causes changes in soil structure and properties, which can provide a basis for reducing the occurrence of natural disasters such as landslides and mud-rock flows, as well as for the construction of roadbed projects, water conservancy projects and municipal projects. The device is easy to disassemble, the infiltration device is not easy to deform, and the materials used are environmentally friendly and economical.

[0042] First, use a computer or RTU (remote terminal unit) to connect the moisture sensor to measure the tested soil samples with different moisture content levels (the moisture content difference is greater than 4%), record the corresponding digital output value, and use a ring knife to take a certain mass of soil samples, transfer them to an aluminum box, send them to the laboratory to dry at 105℃ for 24 hours, and calculate the volumetric moisture content of the soil. Compare the recorded digital output value (V) and the measured soil volumetric moisture content (w v )Use the quadratic equation model to regress various parameters, and the regression formula is as follows:

[0043] w v =A+B·V+C·V 2

[0044] Where: w v is the volumetric water content of soil, A, B, C are regression parameters, and V is the digital output value of the moisture recorder;

[0045] The conversion formula between volumetric quantity and mass moisture content in the moisture field is as follows:

[0046]

[0047] Where: w d is the mass water content of the soil; ρ d is the dry density of the loess sample.

[0048] Each part of the experimental device for infiltration of loess with developed joints described in the present invention can be installed and disassembled, and the maintenance and repair of each part of the device are very convenient.

[0049] The method of the present invention can simulate the water infiltration process of loess with developed open joints under continuous rainfall conditions in the most unfavorable working conditions, realize the dynamic real-time measurement of the water content distribution field during the infiltration process, and quantify the influence of the opening degree on the change process of the infiltration water field of loess with developed joints while minimizing the disturbance of the initial structural state of the soil.

[0050] The present invention is not limited to the above examples. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A device for testing the infiltration of loess with developed joints, characterized in that , comprising an infiltration main device (4), an opening measurement system, a rainfall system, a water flow collection system and a moisture field test system; the opening measurement system is connected to the infiltration main device (4), the rainfall system and the water flow collection system are respectively connected to the infiltration main device (4), and the moisture field test system is connected to the infiltration main device (4); The main infiltration device (4) has two soil samples built in, the two soil samples are separated by a loess joint opening (5), and the rainfall system is directly opposite to the loess joint opening (5); one of the soil samples is fixed, and the other soil sample is placed on a movable trolley (6), and the opening degree of the joint-developed loess body is measured by adjusting the movement of the other soil sample; the loess joint opening (5) is connected to the rainfall system, and the infiltration of rainwater into the joint-developed loess body is tested; The two soil samples include a first soil sample (1) and a second soil sample (14); the first soil sample (1) is arranged on a fixed support (15), and the second soil sample (14) is arranged on a movable trolley (6); the bottom planes of the fixed support (15) and the movable trolley (6) are at the same height; The opening measurement system comprises a nut (8) horizontally arranged on the infiltration main device (4) and a dial indicator (9) connected to the second soil sample (14) box, and the position of the movable trolley (6) is changed by rotating the nut (8) to drive the dial indicator (9) to move and measure the opening of the second soil sample (14); The rainfall system comprises a water storage tank (10), a water conduit (11) and a rainfall trough (3); the water storage tank (10) is connected to the rainfall trough (3) through the water conduit (11) to the loess joint opening (5) between the first soil sample (1) and the second soil sample (14); The water flow collection system comprises a guide pipe (12) and a water flow collection bucket (13), wherein the guide pipe (12) is connected to a position 1 / 4 of the height of the bottom of the side wall of the rainfall trough (3); The moisture field testing system comprises a moisture sensor (16), a data analysis and acquisition instrument (17) and a computer (18); the moisture sensor (16) is arranged in the first soil sample (1) and the second soil sample (14); the moisture sensor (16) is fixed by a rubber plug in a hole opened in a glass panel of an infiltration main device (4); the moisture sensor (16) is connected to the data analysis and acquisition instrument (17) and the computer (18) in sequence.

2. The infiltration test device for loess with developed joints according to claim 1, characterized in that: The middle part of the bottom surface of the rainfall trough (3) is hollowed out, the width of the rainfall trough (3) is the same as the width of the two soil samples, and the hollowing width is the same as the width of the two soil samples.

3. The infiltration test device for loess with developed joints according to claim 1, characterized in that: Vaseline is used to seal the gaps between the rainfall groove (3) and the first soil sample (1) and the second soil sample (14).

4. A method for testing infiltration of loess with developed joints according to the device of any one of claims 1 to 3, characterized in that: The steps include: 1) Place a piece of soil on the movable trolley (6) and the fixed support (15), respectively, with the two pieces of soil close to each other without a gap in between, and apply vaseline on the remaining surfaces except the close surfaces; 2) Turn the nut (8) to adjust the distance between the two soil bodies, and drive the dial indicator (9) to move and measure the opening of the loess body with developed joints; 3) Turn on the rainfall system, read the volumetric water content data at different positions of the soil sample during the infiltration process through the data analysis and acquisition instrument (17), and calculate the mass water content of the measured soil body by the computer (18), obtain the moisture change during the infiltration process, and complete the test of the dynamic evolution process of the moisture field of the jointed loess body during the infiltration process.

5. A test method for infiltration of loess with developed joints according to claim 4, characterized in that: Calculate the volumetric water content of the measured soil , the parameters are regressed using a quadratic equation model, and the regression formula is as follows: in: is the volumetric water content of soil, are the regression parameters, It is the digital output value of the moisture recorder; The conversion formula between volumetric quantity and mass moisture content in the moisture field is as follows: in: is the mass water content of the soil; is the dry density of the loess sample.

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