CN111238963A - Unsaturated soil wet load direct shear test device and humidification strength acquisition method - Google Patents

Unsaturated soil wet load direct shear test device and humidification strength acquisition method Download PDF

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CN111238963A
CN111238963A CN202010095925.4A CN202010095925A CN111238963A CN 111238963 A CN111238963 A CN 111238963A CN 202010095925 A CN202010095925 A CN 202010095925A CN 111238963 A CN111238963 A CN 111238963A
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water
shear
soil
sample
mass
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张莹
狄圣杰
刘奉银
吕庆超
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Xian University of Technology
PowerChina Northwest Engineering Corp Ltd
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Xian University of Technology
PowerChina Northwest Engineering Corp Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0001—Type of application of the stress
    • G01N2203/0003—Steady
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0025—Shearing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract

The invention provides an unsaturated soil wet-load direct shear test device and a humidifying strength acquisition method, which comprise a horizontal platform, a shear box, a shear sample, a fixing device, a vertical loading assembly, a horizontal loading assembly, a humidifying device and an air extractor, wherein the shear box is divided into an upper shear box and a lower shear box; the top of the upper shearing box is provided with a pressure transmitting plate, the vertical loading assembly is arranged on the pressure transmitting plate, the humidifying device is arranged at the top of the upper shearing box, the air exhaust device is arranged on the lower shearing box, and the shearing sample is arranged in the shearing box. According to the invention, the humidifying intensity parameters of the unsaturated soil body under different water contents can be obtained through the humidifying device and the pumping device, so that the stability of the soil body in subsequent construction is more accurately ensured.

Description

Unsaturated soil wet load direct shear test device and humidification strength acquisition method
Technical Field
The invention relates to the technical field of civil engineering, in particular to an unsaturated soil wet load direct shear test device and a humidifying strength acquisition method.
Background
The shear strength of soil is the resistance of the soil body to shear failure, and the failure of building foundations, the sliding of artificial or natural slopes, the movement or toppling of retaining walls, and the like are all caused by the fact that the shear stress in the soil exceeds the shear strength of the soil itself. The unsaturated soil is a composite medium consisting of a solid phase, a liquid phase and a gas phase, is widely distributed, is usually in an unsaturated state in arid and semiarid regions due to the action of weather, and is usually also unsaturated after excavation, remodeling and recompaction. The unsaturated soil has strong structure, high sensitivity to water and electricity and remarkable change of shear strength along with the water content. In actual geotechnical environment, the strength of unsaturated soil is changed when the water content of the soil body is changed due to rainfall or pipeline leakage, and the influence of the water content change of the soil body on the strength cannot be considered by the traditional direct shear test device and the test method, so that the obtained humidifying strength parameter of unsaturated soil has larger difference with the real condition. Therefore, it is an objective need to reasonably provide the strength parameters of unsaturated soil in different states in foundation and foundation engineering, slope engineering, water conservancy and hydropower engineering.
Disclosure of Invention
In order to solve the problem that the influence of the moisture content change of the soil body on the strength cannot be considered by the traditional direct shear test device and the test method, so that the obtained humidifying strength parameter of the unsaturated soil has larger difference with the real situation, and the stability of the soil body is uncertain during construction, the invention provides the unsaturated soil wet-load direct shear test device and the humidifying strength acquisition method.
The technical scheme adopted by the invention is as follows:
a unsaturated soil wet load direct shear test device comprises a horizontal platform, a shear box, a shear sample, a fixing device, a vertical loading assembly, a horizontal loading assembly, a humidifying device and an air extracting device, wherein the shear box is divided into an upper shear box and a lower shear box; the top of the upper shearing box is provided with a pressure transmitting plate, the vertical loading assembly is arranged on the pressure transmitting plate, the humidifying device is arranged at the top of the upper shearing box, the air exhaust device is arranged on the lower shearing box, and the shearing sample is arranged in the shearing box; the inner surface of the top of the upper shearing box and the inner surface of the bottom of the lower shearing box are both provided with a water permeable plate and filter paper, and the bottom of the lower shearing box is provided with a plurality of drain holes.
The fixing device comprises a force measuring steel ring and a vertical platform, and an upper shearing box of the shearing box is fixed on the vertical platform through the force measuring steel ring.
The lower shearing box of the shearing box is arranged on the horizontal platform through a ball.
The humidifying device comprises four water tanks, water tank valves and water tank water pipes, the four water tanks are uniformly distributed around the top of the upper shearing box, the lower end of each water tank is communicated with the inside of the upper shearing box through the corresponding water tank water pipe, and each water tank water pipe is provided with a water tank valve; scales are arranged on the four water tanks.
The air pumping device comprises four air pumps, an air pump valve and air pump water pipes, the four air pumps are distributed around the lower part of the lower shearing box, each air pump is communicated with the inner part of the lower shearing box through the corresponding air pump water pipe, and the air pump valve is arranged on each air pump water pipe.
A method for obtaining the humidifying strength of unsaturated soil wet load direct shear test comprises the following steps:
step one, preparing a shearing sample, and respectively obtaining the mass m of the shearing sample1Mass m of soil particless；
Aligning an upper shearing box and a lower shearing box, placing a water permeable plate and filter paper in the lower shearing box, placing a shearing sample in the shearing box, and placing the filter paper and the water permeable plate on the shearing sample; regulating and controlling a vertical loading assembly to apply vertical pressure to stabilize the solidification deformation of the shear sample;
step three, alternately opening a humidifying device and an air extracting device at the opposite corners to uniformly distribute the water entering the shear sample in the shear sample, recording the volume of the water entering the shear sample, and solving the mass m of the water2；
Step four, after humidifying the shearing sample, applying shearing force to the lower shearing box through a horizontal loading assembly, and shearing until the damage or shearing displacement exceeds 1/10 of the size of the shearing sample;
step five, repeating the steps one to four, and carrying out shear tests on at least 4 shear samples;
step six, respectively measuring the volumes of water in the drain hole and the air pump and calculating the mass m of the water3And m4The added mass of the shear sample is the total mass of water entering the shear sample, so that the water content w of the changed soil sample can be determined;
and step seven, completing a direct shear test to obtain the humidifying strength index of unsaturated soil and ensure the stability of soil body in subsequent construction.
In the step one, the prepared shear sample is a soil sample, and the mass m of the soil sample1The mass m of the soil particles is the natural mass of the soil samplesIs the dry mass of the soil sample.
And in the second step, after the shear sample is applied with vertical pressure, measuring and reading the vertical deformation value every 1h until the deformation per hour is not more than 0.005mm, and judging that the consolidation is stable.
In the third step, the humidifying device and the suction device which are positioned at the opposite corners are sequentially and alternately opened, firstly, a water tank valve corresponding to the first water tank is opened, meanwhile, an air pump valve on a first air pump positioned at the opposite corners of the first water tank is opened, water injected into the first water tank is sucked to the air pump position at the other end below the shear sample from one end above the shear sample through the first air pump, and then, the remaining three water tanks and the corresponding air pumps are opened in the same way, so that the water in the water tanks is uniformly distributed in the shear sample; humidifying the shear specimen, recording the volume of water entering the shear specimen, and calculating the mass m of the water2。
In the sixth step, the volumes of the water in the drain hole and the water in the air pump are respectively measured, and the mass m is calculated3And m4The added mass of the shear sample is the total mass of water entering the soil sample, namely the water volume removed by the drain hole is subtracted from the sum of the water volumes of the four water tanks, so that the water content w of the changed soil sample can be determined;
Figure 189923DEST_PATH_IMAGE001
wherein: m is the total mass of the soil;
Figure 700538DEST_PATH_IMAGE002
the original quality of the soil sample;
Figure 949117DEST_PATH_IMAGE003
adding water into the soil sample for the humidifying device;
Figure 937802DEST_PATH_IMAGE004
the mass of water in the drain hole;
Figure 221015DEST_PATH_IMAGE005
the mass of water in the air pump;
Figure 309057DEST_PATH_IMAGE006
wherein: w is the water content of the soil;
Figure 903987DEST_PATH_IMAGE007
the mass of water in the soil;
Figure 368466DEST_PATH_IMAGE008
the mass of the soil particles;
m is the total mass of the soil;
and drawing a relation curve of the shear stress and the shear displacement according to the test result to obtain the humidification strength of the soil body.
The invention has the beneficial effects that:
(1) the invention can realize dynamic regulation and control of the water content of the sample in the direct shear test process, solves the problem of acquiring the humidifying strength parameter of unsaturated soil, and is simple, convenient and quick in engineering application.
(2) The method is suitable for the value taking problem of unsaturated soil parameters in various actual rock and soil environments, comprises non-pressure humidification, humidification in a shearing process and the like, can be respectively applied to the acquisition of soil body parameters after rainfall, the acquisition of parameters after soil bodies under buildings are soaked in water and the acquisition of parameters in a slope or foundation damage process caused by water soaking, and has wide application range.
(3) The humidifying strength obtained by the invention can effectively reflect the change of the soil shear strength generated by humidifying, and can more truly obtain the shear strength parameter of the unsaturated soil body, thereby guiding the engineering design construction.
Drawings
FIG. 1 is a schematic elevation view of the experimental apparatus of the present invention.
FIG. 2 is a schematic top view of the experimental apparatus of the present invention.
In the figures, the reference numbers are: 1. a humidifying device; 101. a water tank; 102. a water tank valve; 103. a water tank pipe; 2. calibration; 3. an air extraction device; 301. an air pump; 302. an air pump valve; 303. an air pump water pipe; 4. a horizontal platform; 5. a ball bearing; 6. a pressure transmitting plate; 7. a water permeable plate; 8. filtering paper; 9. a cutting box; 901. an upper shearing box; 902. a lower shear box; 10. shearing a sample; 11. a drain hole; 12. a vertical loading assembly; 13. a horizontal loading assembly; 14. a fixing device; 1401. a force measuring steel ring; 1402. a vertical platform.
The following will be further described with reference to the accompanying drawings.
Detailed Description
Example 1:
in order to solve the problem that the influence of the moisture content change of the soil body on the strength cannot be considered by the traditional direct shear test device and the test method, so that the obtained humidifying strength parameter of unsaturated soil has larger difference with the real condition, and the stability of the soil body is uncertain during construction, the invention provides the unsaturated soil wet load direct shear test device and the humidifying strength acquisition method shown in the figures 1 and 2.
A unsaturated soil wet load direct shear test device comprises a horizontal platform 4, a shear box 9, a shear sample 10, a fixing device 14, a vertical loading component 12, a horizontal loading component 13, a humidifying device 1 and an air extracting device 3, wherein the shear box 9 is divided into an upper shear box 901 and a lower shear box 902, the lower shear box 902 is arranged on the horizontal platform 4, one side of the upper shear box 901 is connected with the fixing device 14, and the horizontal loading component 13 is arranged on one side of the lower shear box 902 far away from the fixing device 14; the top of the upper shearing box 901 is provided with a pressure transmitting plate 6, the vertical loading component 12 is arranged on the pressure transmitting plate 6, the humidifying device 1 is arranged on the top of the upper shearing box 901, the air extracting device 3 is arranged on the lower shearing box 902, and the shearing sample 10 is arranged in the shearing box 9; the inner surface of the top of the upper shearing box 901 and the inner surface of the bottom of the lower shearing box 902 are both provided with a water permeable plate 7 and filter paper 8, and the bottom in the lower shearing box 902 is provided with a plurality of water drainage holes 11.
According to the invention, the horizontal loading component 13 acts on one side of the lower shear box 901, and the lower shear box 901 moves through the ball 5, so that the shear load required by the test is provided. The vertical loading assembly 12 acts on the pressure transmitting plate 6, and vertical pressure is transmitted to the shear specimen 10 through the pressure transmitting plate 6 to provide vertical pressure required for the test. The invention changes the moisture content of the shearing sample 10 through the humidifying device 1 and the air extractor 3, and then carries out direct shear test on the basis to obtain the humidifying strength of unsaturated soil, and the test result is closer to the actual engineering.
The vertical loading unit 12 and the horizontal loading unit 13 are conventional units, and will not be further described in the present invention.
The invention can realize dynamic regulation and control of the water content of the sample in the direct shear test process, solves the problem of acquiring the humidifying strength parameter of unsaturated soil, and is simple, convenient and quick in engineering application.
The device is suitable for the value taking problem of unsaturated soil parameters in various actual rock and soil environments, and realizes non-pressure humidification, pressure humidification and humidification in the shearing process through the vertical loading component 12, the horizontal loading component 13, the humidifying device 1 and the air pumping device 3. The method can be respectively applied to the acquisition of soil body parameters after rainfall, the acquisition of parameters after soil body immersion under a building and the acquisition of parameters in the process of slope or foundation damage caused by water immersion, and has wide application range; the humidifying strength obtained by the invention can effectively reflect the change of the soil shear strength generated by humidifying, and can more truly obtain the shear strength parameter of the unsaturated soil body, thereby guiding the engineering design construction.
Example 2:
based on embodiment 1, in this embodiment, the fixing device 14 includes a force measuring steel ring 1401 and a vertical platform 1402, and the upper shear box 901 of the shear box 9 is fixed on the vertical platform 1402 through the force measuring steel ring 1401.
The inventive steel ring 1401 fixes and restrains the upper shear box 901.
Preferably, the lower shear box 902 of the shear box 9 is arranged on the horizontal platform 4 by means of a ball 5.
Preferably, the humidifying device 1 comprises four water tanks 101, water tank valves 102 and water tank water pipes 103, the four water tanks 101 are uniformly distributed around the top of the upper shearing box 901, the lower end of each water tank 101 is communicated with the inside of the upper shearing box 901 through the corresponding water tank water pipe 103, and each water tank water pipe 103 is provided with a water tank valve 102; scales 2 are arranged on the four water tanks 101.
In the invention, water in the water tank 101 is controlled to enter the shear test piece 10 through the water tank valve 102, and the water quantity is controlled according to the scale 2 on the water tank 101.
Preferably, the air pumping device 3 comprises four air pumps 301, air pump valves 302 and air pump water pipes 303, the four air pumps 301 are distributed around the lower portion of the lower shearing box 902, each air pump 301 is communicated with the inside of the lower shearing box 902 through the corresponding air pump water pipe 303, and each air pump water pipe 303 is provided with an air pump valve 302.
According to the invention, the air pump 301 is controlled by the air pump valve 302 to pump air in the shear specimen 10, so that water added by the humidifying device 1 is rapidly and uniformly distributed in the shear specimen 10.
A method for obtaining the humidifying strength of unsaturated soil wet load direct shear test comprises the following steps:
step one, preparing a shear sample 10, and respectively obtaining the mass m of the shear sample 101Mass m of soil particless；
Aligning an upper shearing box 901 and a lower shearing box 902, putting a permeable plate 7 and filter paper 8 in the lower shearing box 902, putting a shearing sample 10 in a shearing box 9, and putting the filter paper 8 and the permeable plate 7 on the shearing sample 10; regulating and controlling the vertical loading component 12 to apply vertical pressure to stabilize the consolidation deformation of the shear sample 10;
step three, alternately opening the humidifying device 1 and the air extracting device 3 at the opposite corners to uniformly distribute the water entering the shear specimen 10 in the shear specimen 10, recording the volume of the water entering the shear specimen 10, and solving the mass m of the water2；
Step four, after humidifying the shear specimen 10, applying shear force to the lower shear box 902 through the horizontal loading component 13, and shearing until the damage or shear displacement exceeds 1/10 of the size of the shear specimen 10;
step five, repeating the steps one to four, and carrying out shear tests on at least 4 shear samples 10;
step six, respectively measuring the volumes of water in the drain hole 11 and the air pump 301 and calculating the mass m of the water3And m4The added mass of the shear sample 10 is the total mass of water entering the shear sample 10, so that the water content w of the changed soil sample can be determined;
and step seven, completing a direct shear test to obtain the humidifying strength index of unsaturated soil and ensure the stability of soil body in subsequent construction.
Preferably, in the first step, the prepared shear test sample 10 is a soil sample, and the soil sample has a mass m1The mass m of the soil particles is the natural mass of the soil samplesIs the dry mass of the soil sample.
Preferably, in the second step, after the shear sample 10 is applied with the vertical pressure, the vertical deformation value is measured every 1h, and the consolidation is judged to be stable until the deformation per hour is not more than 0.005 mm.
Preferably, in the third step, the humidifying device 1 and the suction device 3 located at the opposite corners are alternately opened in sequence, the water tank valve 102 corresponding to the first water tank 101 is opened, the air pump valve 302 on the first air pump 301 located at the opposite corner of the first water tank 101 is opened at the same time, the water injected into the first water tank 101 is sucked from one end above the shear specimen 10 to the air pump 301 at the other end below the shear specimen 10 through the first air pump 301, and then the remaining three water tanks 101 and the corresponding air pumps 301 are opened in the same way, so that the water in the water tanks 101 is uniformly distributed in the shear specimen 10; the humidifying of the shear specimen 10 is completed, the volume of water entering the shear specimen 10 is recorded, and the mass m of the water is obtained2。
Preferably, in the sixth step, the volumes of the water in the water discharging hole 11 and the water in the air pump 301 are measured respectively, and the mass m is determined3And m4The added mass of the sheared sample 10 is the total mass of water entering the soil sample, namely the water amount removed by the drain hole 11 is subtracted from the sum of the water amounts of the four water tanks 101, so that the water content w of the soil sample after being changed can be determined;
Figure 240607DEST_PATH_IMAGE009
wherein: m is the total mass of the soil;
Figure 325981DEST_PATH_IMAGE002
the original quality of the soil sample;
Figure 345890DEST_PATH_IMAGE003
adding water into the soil sample for the humidifying device;
Figure 286164DEST_PATH_IMAGE004
the mass of water in the drain hole;
Figure 75128DEST_PATH_IMAGE005
the mass of water in the air pump;
Figure 832869DEST_PATH_IMAGE006
wherein: w is the water content of the soil;
Figure 340074DEST_PATH_IMAGE007
the mass of water in the soil;
Figure 818460DEST_PATH_IMAGE008
the mass of the soil particles;
m is the total mass of the soil;
and drawing a relation curve of the shear stress and the shear displacement according to the test result to obtain the humidification strength of the soil body.
The steps for obtaining the humidifying strength of the unsaturated soil are as follows:
step 1: preparing soil samples according to the standard GB/T50123-2019 of soil test method, and respectively obtaining the mass m of the soil samples1Mass m of soil particless；
Step 2: after the permeable plate 7 and the filter paper 8 are placed in the lower cutting box 902 by aligning the upper and lower cutting boxes, the soil sample is placed in the cutting box 9, and the filter paper 8 and the permeable plate 7 are placed on the soil sample. And regulating the vertical loading assembly 12 to apply vertical pressure to stabilize the consolidation deformation of the sample. And (3) after the soil sample is applied with vertical pressure, measuring and reading the vertical deformation value every 1h until the deformation per hour is not more than 0.005mm, and judging that the consolidation is stable.
And step 3: sequentially and alternately opening the humidifying device 1 and the suction device 3 at opposite corners, firstly opening the corresponding water tank valve 102 of the first water tank 101, simultaneously opening the air pump valve 302 on the first air pump 301 at the opposite corner of the first water tank 101, and enabling the first water tank to be connected through the first air pump 301The water injected into the water tank 101 is pumped from one end above the soil sample to the air pump 301 at the other end below the soil sample, and then the remaining three water tanks 101 and the corresponding air pumps 301 are opened in the same way, so that the water in the water tanks 101 is uniformly distributed in the soil sample; humidifying the soil sample to uniformly distribute the water in the soil, recording the volume of the water in the soil, and calculating the mass m2. The amount of water entering the soil sample is controlled by the humidifying device 1, the amount of water entering the soil body is the sum of the amounts of water entering the four water tanks 101, and air existing in the unsaturated soil body is sucked by the air suction device 3, so that the water is accelerated to move in the soil sample.
And 4, step 4: after the soil sample is moisturized, shear is applied to the test by the horizontal loading assembly 13 until failure or shear displacement exceeds 1/10 for the sample size. The soil sample can be humidified before or during the shearing process, and the humidification is performed respectively corresponding to the pressure humidification and the shearing process.
And 5: repeating steps 1-4 for at least 4 samples of shear test.
Step 6: the volume of water in the drain hole and the air pump is respectively measured and the mass m is calculated3And m4The added mass of the soil sample is the total mass of water entering the soil sample, namely the water volume removed by the water discharge hole 11 is subtracted from the sum of the water volumes of the four water tanks 101, so that the water content w of the soil sample after being changed can be determined.
Figure 727510DEST_PATH_IMAGE009
Wherein: m is the total mass of the soil;
Figure 390572DEST_PATH_IMAGE002
the original quality of the soil sample;
Figure 385073DEST_PATH_IMAGE003
adding water into the soil sample for the humidifying device;
Figure 932729DEST_PATH_IMAGE004
the mass of water in the drain hole;
Figure 758603DEST_PATH_IMAGE005
the mass of water in the air pump.
Figure 795829DEST_PATH_IMAGE006
Wherein: w is the water content of the soil;
Figure 949730DEST_PATH_IMAGE007
the mass of water in the soil;
Figure 97814DEST_PATH_IMAGE008
the mass of the soil particles;
and m is the total mass of the soil.
And 7: and determining the humidifying strength index of the soil according to the test result and the coulomb strength theory.
And drawing a relation curve of the shear stress and the shear displacement according to the test result to obtain the humidification strength of the soil body.
The invention can realize dynamic regulation and control of the water content of the sample in the direct shear test process, solves the problem of acquiring the humidifying strength parameter of unsaturated soil, and has simple, convenient and quick engineering application; the method is suitable for the value taking problem of unsaturated soil parameters in various actual rock and soil environments, comprises non-pressure humidification, humidification in a shearing process and the like, can be respectively applied to the acquisition of soil body parameters after rainfall, the acquisition of parameters after soil bodies under buildings are soaked in water and the acquisition of parameters in a slope or foundation damage process caused by water soaking, and has wide application range.
The humidifying strength obtained by the invention can effectively reflect the change of the soil shear strength generated by humidifying, and can more truly obtain the shear strength parameter of the unsaturated soil body, thereby guiding the engineering design construction.
The above examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention, which is intended to be covered by the claims and any design similar or equivalent to the scope of the invention. The device structure and the system method which are not described in detail in the embodiment are all the well-known technologies and common methods in the industry, and are not described one by one here.

Claims (10)

1. The utility model provides a direct shear test device is carried to unsaturated soil wet-load which characterized in that: the device comprises a horizontal platform (4), a shearing box (9), a shearing sample (10), a fixing device (14), a vertical loading component (12), a horizontal loading component (13), a humidifying device (1) and an air extracting device (3), wherein the shearing box (9) is divided into an upper shearing box (901) and a lower shearing box (902), the lower shearing box (902) is arranged on the horizontal platform (4), one side of the upper shearing box (901) is connected with the fixing device (14), and the horizontal loading component (13) is arranged on one side, far away from the fixing device (14), of the lower shearing box (902); the top of the upper shearing box (901) is provided with a pressure transmitting plate (6), the vertical loading component (12) is arranged on the pressure transmitting plate (6), the humidifying device (1) is arranged on the top of the upper shearing box (901), the air extracting device (3) is arranged on the lower shearing box (902), and the shearing sample (10) is arranged in the shearing box (9); the inner surface of the top of the upper shearing box (901) and the inner surface of the bottom of the lower shearing box (902) are respectively provided with a water permeable plate (7) and filter paper (8), and the bottom in the lower shearing box (902) is provided with a plurality of water drainage holes (11).
2. The unsaturated soil wet load direct shear test device of claim 1, wherein: the fixing device (14) comprises a force measuring steel ring (1401) and a vertical platform (1402), and an upper shearing box (901) of the shearing box (9) is fixed on the vertical platform (1402) through the force measuring steel ring (1401).
3. The unsaturated soil wet load direct shear test device of claim 1, wherein: the lower shearing box (902) of the shearing box (9) is arranged on the horizontal platform (4) through a ball bearing (5).
4. The unsaturated soil wet load direct shear test device of claim 1, wherein: the humidifying device (1) comprises four water tanks (101), water tank valves (102) and water tank water pipes (103), wherein the four water tanks (101) are uniformly distributed around the top of the upper shearing box (901), the lower end of each water tank (101) is communicated with the inside of the upper shearing box (901) through the corresponding water tank water pipe (103), and the water tank valve (102) is arranged on each water tank water pipe (103); scales are arranged on the four water tanks (101).
5. The unsaturated soil wet load direct shear test device of claim 1, wherein: air exhaust device (3) include four air pumps (301), air pump valve (302) and air pump water pipe (303), four air pumps (301) distribute around shearing box (902) lower part down, every air pump (301) all through corresponding air pump water pipe (303) with shear box (902) inside intercommunication down, all be equipped with air pump valve (302) on every air pump water pipe (303).
6. The method for acquiring the humidifying strength of the unsaturated soil wet-load direct shear test according to any one of claims 1 to 5, wherein the method comprises the following steps: the method comprises the following specific steps:
step one, preparing a shear sample (10) and respectively obtaining the mass m of the shear sample (10)1Mass m of soil particless；
Aligning an upper shearing box (901) and a lower shearing box (902), putting a permeable plate (7) and filter paper (8) in the lower shearing box (902), putting a shearing sample (10) in a shearing box (9), and putting the filter paper (8) and the permeable plate (7) on the shearing sample (10); regulating and controlling the vertical loading component (12) to apply vertical pressure to stabilize the consolidation deformation of the shear sample (10);
step three, alternately opening the humidifying device (1) and the air extracting device (3) at the opposite corners to ensure that the moisture entering the shear specimen (10) is uniformDistributed in the shear sample (10), recording the volume of water entering the shear sample (10), and solving the mass m of the water2；
Step four, after humidifying the shear specimen (10), applying shear force to the lower shear box (902) through the horizontal loading component (13) to carry out shearing until the damage or shear displacement exceeds 1/10 of the size of the shear specimen (10);
step five, repeating the steps one to four, and carrying out shear tests on at least 4 shear samples (10);
step six, respectively measuring the volumes of water in the drain hole (11) and the air pump (301) and calculating the mass m of the water3And m4The added mass of the shear sample (10) is the total mass of water entering the shear sample (10), so that the water content w of the changed soil sample can be determined;
and step seven, completing a direct shear test to obtain the humidifying strength index of unsaturated soil and ensure the stability of soil body in subsequent construction.
7. The method for acquiring the humidifying strength of the unsaturated soil wet-load direct shear test according to claim 6, wherein the method comprises the following steps: in the step one, the prepared shear sample (10) is a soil sample, and the mass m of the soil sample1The mass m of the soil particles is the natural mass of the soil samplesIs the dry mass of the soil sample.
8. The method for acquiring the humidifying strength of the unsaturated soil wet-load direct shear test according to claim 6, wherein the method comprises the following steps: in the second step, after the shear sample (10) is applied with vertical pressure, the vertical deformation value is measured and read every 1h until the deformation per hour is not more than 0.005mm, and then the consolidation is judged to be stable.
9. The method for acquiring the humidifying strength of the unsaturated soil wet-load direct shear test according to claim 6, wherein the method comprises the following steps: in the third step, the humidifying device (1) and the suction device (3) which are positioned at the opposite corners are sequentially and alternately opened, the water tank valve (102) corresponding to the first water tank (101) is firstly opened, and meanwhile, the first water tank valve (102) is openedOpening an air pump valve (302) on a first air pump (301) positioned at the opposite corner of the first water tank (101), sucking water injected into the first water tank (101) from one end above the shear specimen (10) to the air pump (301) at the other end below the shear specimen (10) through the first air pump (301), and then similarly opening the remaining three water tanks (101) and the corresponding air pumps (301) to uniformly distribute the water in the water tanks (101) in the shear specimen (10); humidifying the shear specimen (10) is completed, the volume of water entering the shear specimen (10) is recorded, and the mass m of the water is obtained2。
10. The method for acquiring the humidifying strength of the unsaturated soil wet-load direct shear test according to claim 6, wherein the method comprises the following steps: in the sixth step, the volumes of the water in the drain hole (11) and the water in the air pump (301) are respectively measured, and the mass m is obtained3And m4The added mass of the sheared sample (10) is the total mass of water entering the soil sample, namely the water quantity removed by the drain hole (11) is subtracted from the sum of the water quantities of the four water tanks (101), so that the water content w of the soil sample after being changed can be determined;
Figure DEST_PATH_IMAGE002
wherein: m is the total mass of the soil;
Figure DEST_PATH_IMAGE004
the original quality of the soil sample;
Figure DEST_PATH_IMAGE005
adding water into the soil sample for the humidifying device;
Figure DEST_PATH_IMAGE006
the mass of water in the drain hole;
Figure DEST_PATH_IMAGE007
the mass of water in the air pump;
Figure DEST_PATH_IMAGE008
wherein: w is the water content of the soil;
Figure DEST_PATH_IMAGE009
the mass of water in the soil;
Figure DEST_PATH_IMAGE010
the mass of the soil particles;
m is the total mass of the soil;
and drawing a relation curve of the shear stress and the shear displacement according to the test result to obtain the humidification strength of the soil body.
CN202010095925.4A 2020-02-17 2020-02-17 Unsaturated soil wet load direct shear test device and humidification strength acquisition method Pending CN111238963A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111896446A (en) * 2020-07-09 2020-11-06 河海大学 Contact surface shear seepage test device and test method considering temperature effect
CN112683695A (en) * 2021-01-06 2021-04-20 四川农业大学 Simple direct shearing device for root-soil complex and using method
CN114018700A (en) * 2021-10-26 2022-02-08 中国电力工程顾问集团华北电力设计院有限公司 Large-scale soil-rock mixed soil sample indoor compression instrument and filling deformation and stability calculation method
CN116793861A (en) * 2023-08-28 2023-09-22 安徽建筑大学 Irregular rock mass shear test device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111896446A (en) * 2020-07-09 2020-11-06 河海大学 Contact surface shear seepage test device and test method considering temperature effect
CN112683695A (en) * 2021-01-06 2021-04-20 四川农业大学 Simple direct shearing device for root-soil complex and using method
CN112683695B (en) * 2021-01-06 2023-06-30 四川农业大学 Simple direct shearing device for root soil complex and use method
CN114018700A (en) * 2021-10-26 2022-02-08 中国电力工程顾问集团华北电力设计院有限公司 Large-scale soil-rock mixed soil sample indoor compression instrument and filling deformation and stability calculation method
CN116793861A (en) * 2023-08-28 2023-09-22 安徽建筑大学 Irregular rock mass shear test device

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