Direct shear test system for seasonally frozen ground and test method thereof

A test system and seasonal technology, applied in the field of frozen soil shear test equipment, can solve the problems of no direct shear test and frozen soil field simulation, and no realization of on-site freezing and thawing cycle of soil mass.

Inactive Publication Date: 2019-03-19
CHONGQING JIAOTONG UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] In the prior art, there is no on-site freeze-thaw cycle of soil, and there is no on-site simulation of the combination of direct shear test and frozen soil

Method used

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  • Direct shear test system for seasonally frozen ground and test method thereof
  • Direct shear test system for seasonally frozen ground and test method thereof
  • Direct shear test system for seasonally frozen ground and test method thereof

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Experimental program
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Embodiment 1

[0030] see figure 1 , this embodiment discloses a seasonal frozen soil direct shear test system, including a shear box arranged on a test platform, a freeze-thaw cycle system and a loading system.

[0031] see Figure 4 , the shear box is made of PEEK resin (polyether ether ketone). The shear box as a whole is a rectangular box. The four side walls of the rectangular box are sequentially the first side wall, the second side wall, the third side wall and the fourth side wall. A liquid nitrogen cooling chamber is enclosed in the second side wall and the fourth side wall of the shear box. The shear box can be split into an upper shear box 7 and a lower shear box 10 . The upper shear box 7 is a rectangular frame as a whole. Heating nitrogen vents 9 are provided on the first side wall and the third side wall of the upper shear box 7 . A liquid nitrogen injection port 14 is provided on the second side wall and the fourth side wall of the upper shear box 7 . The lower shear bo...

Embodiment 2

[0038] This embodiment discloses a kind of test method about the seasonal frozen soil direct shear test system described in embodiment 1, comprising the following steps:

[0039] 1) Put soil in the shear box and compact it. Open the freeze-thaw cycle system to realize the freeze-thaw cycle of the soil.

[0040] 2) The automatic vertical pressing device 5 applies a vertical load to the sample, and the automatic horizontal pushing device 6 applies a horizontal thrust to the lower shear box 10 .

[0041] 3) The data acquisition instrument 2 collects and records shear stress data and shear displacement data. After the data acquisition instrument 2 preliminarily processes the data, it transmits the data to the computer.

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Abstract

The invention provides a direct shear test system for seasonally frozen ground and a test method thereof. The test system comprises a shear box, a freeze thawing circulating system and a loading system arranged on a test platform. A liquid nitrogen cooling room is packaged on the side wall of the shear box, and the shear box can be divided into an upper shear box and a lower shear box. During work, a tested frozen ground is placed in the inner cavity of the shear box. Liquid nitrogen flows circularly between the liquid nitrogen cooling room and a liquid nitrogen cooling device. Heated nitrogenflows circularly between the inner cavity of the shear box and a nitrogen heating ventilating device, so that freezing and thawing cycle of the ground is achieved. An automatic vertical pressurizingdevice applies a positive stress to the frozen ground sample and an automatic horizontal pushing device applies a horizontal thrust to the lower shear box. The test method of the test system comprisesthe steps of preparing a ground sample, applying a direct load, collecting record data and the like. The test system can be used for observing microscomic characteristics in a test sample testing process. The system and method can achieve freezing and thawing cycle of on-site ground and simulate the freezing and thawing cycle action in sunlight.

Description

technical field [0001] The invention relates to the technical field of engineering frozen soil, in particular to frozen soil shear test equipment. Background technique [0002] Frozen soil refers to various rocks and soils with a temperature at or below 0°C and contains ice. It is extremely sensitive to temperature and contains abundant underground ice. Therefore, permafrost has rheological properties, and its long-term strength is much lower than the instantaneous strength characteristics. Because of these characteristics, construction of engineering structures in permafrost must face two major dangers: frost heaving and thawing. What plays an important role is the existence form of water. When the water turns into ice, the volume increases, which makes the soil expand, and the surface of the earth is arched and raised, which is frost heaving; when the ice in the soil turns into water, the volume increases. When it shrinks, the surface will melt and sink, which is referre...

Claims

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Application Information

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IPC IPC(8): G01N3/24G01N3/02
CPCG01N3/02G01N3/24G01N2203/0025G01N2203/0228
Inventor 邱珍锋杨少博李施衡王俊杰
Owner CHONGQING JIAOTONG UNIVERSITY
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