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Unsaturated soil direct-shear test device with function of controlling suction by negative pore water pressure

A test device and negative pore technology, applied in the direction of testing the strength of materials by applying stable shear force, can solve the problem that the structure of direct shear instrument is complex, it is difficult to truly reflect the suction state of natural unsaturated soil, and increase the airtightness of pressure chamber To achieve the effect of avoiding the airtightness of the pressure chamber, simple structure and simple structure of the instrument

Inactive Publication Date: 2015-01-07
SHANGHAI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At the same time, the commonly used unsaturated soil direct shear instrument seals the shearing system of the entire direct shear instrument with a sealed pressure chamber in order to add air pressure to the soil sample, which not only makes the structure of the direct shear instrument complicated, but also increases the holding pressure. It is difficult to truly reflect the suction state of natural unsaturated soil due to the airtightness of the chamber

Method used

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  • Unsaturated soil direct-shear test device with function of controlling suction by negative pore water pressure
  • Unsaturated soil direct-shear test device with function of controlling suction by negative pore water pressure
  • Unsaturated soil direct-shear test device with function of controlling suction by negative pore water pressure

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Embodiment 1

[0035] In this example, see Figure 1 to Figure 12, a direct shear test device for unsaturated soil with negative pore water pressure controlling suction, mainly including a direct shear instrument, the direct shear instrument includes an upper shear box 1, a lower shear box 2, a water-permeable and air-impermeable clay plate 7 and a loading system , the clay plate 7 is fixedly installed on the bottom of the lower shear box 2, and the upper surface of the bottom of the lower shear box 2 in direct contact with the clay plate 7 is provided with a spiral groove 13. The hole 11 is connected, and the soil sample 6 is placed in the direct shear box formed by the combination of the upper shear box 1, the lower shear box 2 and the upper cover 4 of the shear box, the upper shear box 1 and the lower shear box 2 The inner cavities have the same shape and equal size to form a ring knife sample. The soil sample 6 is placed on the clay plate 7, and a permeable stone 5 is set under the shear...

Embodiment 2

[0055] This embodiment is basically the same as Embodiment 1, especially in that:

[0056] In this embodiment, the filter paper 23 is polyvinyl fluoride filter paper. Polyvinyl fluoride filter paper has the function of ventilation and impervious to water, which can better prevent the water content of soil sample 6 from being affected by atmospheric evaporation, and make the weight sensor 25 measure the water content of soil sample 6 more accurately. Polyvinyl fluoride filter paper Low cost, strong adhesion, easy to use.

Embodiment 3

[0058] This embodiment is basically the same as the previous embodiment, and the special features are:

[0059] In this embodiment, the weight sensor 25 is an electronic balance, which is easy to use, low in cost and high in precision.

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Abstract

The invention discloses an unsaturated soil direct-shear test device with a function of controlling the suction by the negative pore water pressure. The unsaturated soil direct-shear test device comprises a direct-shear apparatus, a soil body water content change measurement system, and a positive and negative pressure conversion system, wherein the soil body water content change measurement system is composed of a dryer, a water container and a weight sensor; the positive and negative pressure conversion system is composed of a positive pressure control meter, a negative pressure control meter, a pressure converter and an air compressor; the loading system comprises a vertical load loading system and a horizontal load loading system; and the bottom surface of a lower shear box and the upper surface of a base oppositely slide in parallel through a sliding pair. By using the unsaturated soil direct-shear test device disclosed by the invention, a natural state of an unsaturated soil body is really reproduced when the suction is controlled; the effect of the suction of unsaturated soil on the shearing strength can be accurately tested; and meanwhile, the structure of the common unsaturated soil direct-shear apparatus at present is simplified. The unsaturated soil direct-shear test device disclosed by the invention is simple in structure, convenient to operate and easy to grasp.

Description

technical field [0001] The invention relates to a civil engineering geotechnical test device, in particular to a test device for the influence of the suction change of unsaturated soil on its strength, which is applied to the geotechnical test of geotechnical engineering. Background technique [0002] Most of the earth's surface is in an arid or semi-arid zone, so most of the soil encountered in geotechnical engineering is in an unsaturated state, such as sandy soil, silt, collapsible loess, expansive soil, tropical residual soil, etc. Soil, it is very necessary to study the properties of unsaturated soil. In particular, sandy soil and silt soil have larger permeability coefficients and are more easily affected by rainfall or atmospheric evaporation. The surface layer of natural slopes and artificial slopes is mostly unsaturated sandy soil and silt soil. During the rainfall process, rainwater seeps into the soil and the groundwater level rises, which increases the saturatio...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/24
Inventor 孙德安张俊然吴义高贾磊刘文捷
Owner SHANGHAI UNIV
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