Airbag-loading potable weak and soft interlayer direct shear apparatus

Abstract

The invention provides a simple, accurate and field airbag-loading potable soft and weak interlayer direct shear apparatus. In the direct shear apparatus, airbag loading is adopted to apply a normal force, and a piston system arranged on the upper part of a reaction frame can guarantee the verticality and application uniformity of the normal force when a sample produces shearing displacement; and a ball screw system applies a tangential force and linear guides under a sample seat can guarantee the horizontality of the application direction of the shearing force and the continuity and smoothness of the tangential force. A normal force applying system avoids bearing load, and airbag pressurization is accomplished by a potable pressurizing device and is high in precision, simple and easy to implement. A tangential force applying system uses a screw handle to apply force and the force application is steady and highly operable. Both the normal force applying system and the tangential force applying system are fixed, small in volume, high in reliability and convenient in on-site test. The test device can perform the quick shearing of field soft and weak interlayer and consolidated drained quick and slow shear tests and is simple, precise and high in operability.

Description

technical field [0001] Technical Field of Soil Mechanics Test Background technique [0002] Weak interlayers belong to the soil body, and the existing soil mechanics shear tests are divided into indoor tests and in-situ tests. There are two main types of indoor shear tests: direct shear tests and triaxial compression tests. In the direct shear test, a lever is used to apply a normal pressure to the soil sample with a weight, and then a horizontal thrust is applied to cause the sample to fail along a predetermined shear plane. The shear strength parameters C and φ values ​​of the samples were calculated by multiple sets of direct shear tests. For weak interlayers, the direct shear test has the advantages of simple test operation, small sample volume, and less time-consuming; the disadvantage is that the weak interlayer is easily disturbed, and the instrument is heavy, so it cannot be tested on site. [0003] The triaxial compression test is to apply confining pressure to t...

AI Technical Summary

Problems solved by technology

The advantage of the triaxial compression test is that it can obtain the shear parameters under the real stress state of the sample. The disadvantage is that the instrument is sophisticated and complex, the sample size is large, and it takes a long time, so it cannot be tested on site.

The common disadvantages of the two indoor tests are: the original sample is not easy to obtain, and the sample is easily disturbed during packaging and transportation; the test cannot be carried out on site, and the test results can be obtained quickly

This method can obtain the soil cohesion C, friction angle value, but the disadvantage is that it consumes more funds, time and labor, the equipment is cumbersome, and the operability is not strong

[0005] In short, there are currently two types of soil mechanics shear test methods. The first two indoor test methods are easy to disturb the samples during packaging and transportation, and it is not easy to carry out the original sample test; and the test results cannot be quickly obtained on site.

The latter two in-situ tests, one can only test the undrained shear strength of saturated soft clay, and the other test equipment is bulky, time-consuming and laborious, and has poor operability

None of the existing soil mechanics shear test methods can meet the requirements of quickly and conveniently obtaining the shear parameters of undisturbed soil samples in weak interlayers.

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