Shearing instrument for freeze-thaw cycle shear test and test method

A shear test, freeze-thaw cycle technology, applied in the direction of using a stable shear force to test the strength of materials, instruments, scientific instruments, etc. Achieve accurate data measurement, improve cooling effect, and work stably

Pending Publication Date: 2022-05-03
LANZHOU JIAOTONG UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the soil shear strength test instruments currently on the market are mainly designed for non-frozen soil. These instruments are characterized by simple operation and mature technology, but they can only test the shear strength of thawed soil, and cannot test the resistance of the freeze-thaw interface. The shear strength cannot record the dynamic changes of horizontal force and horizontal displacement in real time, and the formation process of the actual freeze-thaw interface in the field is relatively complicated and greatly affected by temperature.
Due to the small size of the soil sample and the limited function of the test device, the current shear test cannot monitor and measure the internal temperature change in real time.

Method used

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  • Shearing instrument for freeze-thaw cycle shear test and test method
  • Shearing instrument for freeze-thaw cycle shear test and test method
  • Shearing instrument for freeze-thaw cycle shear test and test method

Examples

Experimental program
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Effect test

Embodiment 1

[0040] refer to Figure 1-3As shown, a shearing instrument for freeze-thaw cycle shear test includes a shearing instrument main body, a refrigeration system and a data acquisition system; the shearing instrument main body includes a pressure rod 2, an insulating layer 5, an upper shear box 7, The lower shear box 8, the permeable plate 9, the upper permeable stone 11, the horizontal thrust rod 15, the shear transmission mechanism 16, the roller 17, the bottom plate 18, the lower permeable stone 19 and the supporting plate 23, the lower shear box 8 is installed on the support The top of the plate 23, the roller 17 is installed on the bottom of the supporting plate 23, the horizontal thrust rod 15 is installed on one side of the supporting plate 23, the shear transmission mechanism 16 is installed on the bottom of the horizontal thrust rod 15, the shear transmission mechanism 16 and the roller The shafts 17 are all installed on the top of the base plate 18, the top of the base pl...

Embodiment 2

[0053] On the basis of embodiment 1, the present invention also provides a kind of experimental method that is used for freeze-thaw cycle shear test, comprises the following steps:

[0054] (1) Put the prepared soil sample model 21 into the experimental shear box composed of the upper shear box 7 and the lower shear box 8 according to the test plan. Wrap the upper shear box 7 and the lower shear box 8 to form an insulating layer 5 around the experimental shear box;

[0055] (2) After connecting the temperature sensor 12 through the temperature sensor lead wire 20, lead out the connection data acquisition device through the sensor lead hole of the experimental shear box;

[0056] (3) Connect the pressure rod 2 vertically to the center of the upper permeable stone 11, install the pressure sensor 1 on the pressure rod 2, install the horizontal displacement gauge 10 and the dynamometer 6 on the horizontal rod of the reaction force device 22;

[0057] (4) Connect the first cold li...

Embodiment 3

[0061] In order to better test and illustrate the present invention, the present invention is used to conduct a freeze-thaw cycle shear test on a soil sample with a size of 200mm×200mm (diameter×height). The test soil sample is Lanzhou loess, the particle size d≤2mm, and the initial water content is 16%.

[0062] The method in Example 2 was used to conduct a shear test on the experimental soil sample, and the test mainly tested elements such as temperature, horizontal displacement, horizontal force, and vertical pressure of the soil sample.

[0063] Figure 4 The curves of soil sample temperature changing with time after two freeze-thaw cycles are given, from Figure 4 It can be seen that the temperature change curve changes regularly. After cooling down, let the temperature maintain a certain stable process, and then return to the temperature. Temperature is the direct basis for the distribution and transfer of heat in the soil, and this curve reflects the characteristics o...

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Abstract

The invention relates to the technical field of test devices and test methods thereof, in particular to a shear apparatus for a freeze-thaw cycle shear test and a test method, the shear apparatus comprises a shear apparatus main body, a refrigeration system and a data acquisition system; according to the invention, the shearing instrument is connected with external refrigeration equipment, so that intelligent control of the internal environment temperature of the shearing box is realized, and automatic acquisition of dynamic reaction values in the freezing and thawing cycle and shearing process of the soil sample is realized through a temperature sensor embedded in the soil sample and a pressure sensor, a dynamometer and a horizontal displacement meter which are mounted at the top of a pressure rod; the device is mainly used for the freezing and thawing cycle shear test of frozen soil and thawed soil interfaces of roads or railways in cold regions, can simulate the forming process of the frozen soil freezing and thawing interfaces, has the advantages of low cost and high similarity, and can remarkably improve the efficiency of the soil freezing and thawing cycle shear test.

Description

technical field [0001] The invention relates to the technical field of a test device and a test method thereof, in particular to a shear instrument and a test method for a freeze-thaw cycle shear test. Background technique [0002] As the third largest frozen soil country in the world, my country has a wide distribution of frozen soils, most of which are located in earthquake zones, resulting in extremely complex mechanical properties of the corresponding foundation soils. Especially in seasonally frozen soil regions, the surface soil freezes as the temperature drops, forming a stable and clear freeze-thaw interface inside the soil. Usually, the dynamic shear modulus and damping ratio of frozen soil are 30-50 times and 2 times that of thawed soil, respectively. Frozen soil has characteristics such as nonlinearity, hysteresis, and strain accumulation under cyclic loading. Therefore, the strain of the soil at the freeze-thaw interface is discontinuous, and the mechanical prop...

Claims

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Application Information

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IPC IPC(8): G01N3/24G01N3/02
CPCG01N3/24G01N3/02G01N2203/0003G01N2203/0025G01N2203/0228G01N2203/0258G01N2203/0676G01N2203/0682G01N2203/0694
Inventor 高建强杜文睿江东阁
Owner LANZHOU JIAOTONG UNIV
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