Multi-boundary-condition dilatometer and soil expansion test method

Abstract

The invention discloses a multi-boundary-condition dilatometer and a soil expansion test method. The multi-boundary-condition dilatometer comprises a lower supporting platform, an upper fixed frame, a boundary condition simulating mechanism, a sample carrying chamber and a measuring mechanism. The upper fixed frame, the boundary condition simulating mechanism and the sample carrying chamber are all mounted on the lower supporting platform, and the measuring mechanism is mounted in the upper fixed frame. An equal-rigidity flexible boundary simulating unit is designed, meanwhile, a constant-size and constant-stress boundary simulating unit is integrated, and compared with a traditional dilatometer, a test can be carried out under multiple boundary conditions, and the influence of the boundary conditions on the expansion performance of soil is analyzed. Different test paths can be designed, and the influence of the test paths on the expansion performance of soil can be analyzed. A sensing measuring device and a data collecting device are adopted, testing precision is high, and data collecting are convenient. The device is simple and novel in structure, easy and convenient to operate, small in influence from human factors, low in cost and reliable in data.

Description

technical field [0001] The invention belongs to the technical field of laboratory tests in geotechnical engineering and geological engineering, and more specifically relates to a dilatometer and a soil body capable of simulating different boundary conditions (constant stress, constant volume and equal stiffness) and freely designing test paths Swell test method. Background technique [0002] Expansive soils are widely distributed in various regions of the world. Due to geographical constraints, many buildings have to be built on expansive soil foundations. In recent years, under the influence of extreme climate, engineering accidents caused by foundation damage due to water absorption and swelling deformation of soil often occur, which has a great impact on people's property safety. On the contrary, taking advantage of the special properties of expansive soil, the buffer / backfill materials mainly composed of bentonite can also be used in anti-seepage structures of special ...

AI Technical Summary

Problems solved by technology

[0007] (1) Only the two extreme boundary conditions of constant stress and constant volume are considered, but the flexible boundary conditions widely existing in practical engineering are not considered;

[0008] (2) The commonly used boundary condition control methods are complex to operate and are easily affected by human factors;

[0009] (3) Boundary conditions cannot be converted during the test

[0010] After searching, the Chinese patent application number 201510322064.8, the application date is June 2, 2015, and the name of the invention is: two-dimensional dilatometer for expansive soil; the application includes a test bench and a pressure chamber set on the test bench, the pressure chamber is A square tubular structure with openings at the left and right ends surrounded by the bottom plate, the top plate, the front splint and the rear splint, which are arranged alternately up and down. The enclosed space constitutes the storage space for the test soil samples. The sliding mechanism is connected to the loading mechanism on the test bench through a flexible rope. The first displacement sensor for measuring its vertical displacement is arranged on the pressure transmission plate. There is a second displacement sensor for measuring its horizontal displacement; the application is a two-dimensional dilatometer for expansive soil, which can effectively solve the problem that the dilatometer simultaneously measures expansion deformation and expansion force in both vertical and lateral directions; However, this application cannot change the boundary conditions where the sample is located, and realize arbitrary conversion of various boundary conditions (constant pressure, constant volume and equal stiffness), and further improvement is still needed

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