Determination method and apparatus for coefficient of earth pressure at rest

Abstract

The invention provides a determination method and a determination apparatus for the coefficient of earth pressure at rest, belonging to coefficient measuring methods and apparatuses for soil tests. In a conventional triaxial pressure chamber, an axial deformation constrained radial loading test is carried out on a soil sample so as to obtain a ratio of axial stress to radial stress; according to a two-dimensional asymptotic state criterion, relationship between a starting friction angle and a triaxial compression friction angle in the axial deformation constrained radial loading test satisfies equation I described in the specification, and relationship between the starting friction angle and the triaxial compression friction angle in a radial deformation constrained axial loading test satisfies equation II described in the specification. According to calculation results, the coefficient of earth pressure at rest in the axial deformation constraint radial loading test is 0.5 time of the ratio of axial stress to radial stress in the axial deformation constraint radial loading test. According to the method, errors generated when fixed section radial deformation control is used to substitute radial deformation control in a vertical direction of the soil sample in the radial deformation constrained axial loading test for the coefficient of earth pressure at rest can be avoided, and the method and the apparatus are suitable for accurate determination of coefficients of earth pressure at rest of saturated sand.

Description

technical field [0001] The invention relates to a method and a device for measuring a coefficient of a soil engineering test, in particular to a method and a device for measuring a static earth pressure coefficient. Background technique [0002] Static earth pressure coefficient is the ratio of radial pressure to axial pressure obtained under the premise of ensuring that the lateral deformation of the soil sample is zero. express. Therefore, effectively controlling the radial deformation of the soil sample and accurately obtaining the radial stress on the soil sample become the key to the success or failure of the determination of the static earth pressure coefficient. At present, according to the radial deformation control method of soil samples, the indoor measurement methods of static earth pressure coefficient can be divided into two categories: ① rigid pressure chamber, flexible confinement conditions or radial deformation sensor constraints. Airless water or oil is ...

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Problems solved by technology

The actual liquid can be compressed under high pressure conditions. Method ① has good applicability under normal pressure conditions, but with the continuous increase of consolidation stress, the liquid in the pressure chamber will be compressed, and the soil sample will expand and deform, making the measured static The earth pressure coefficient is too small

However, the method based on radial deformation sensor constraints can only control the deformation at the middle position of the soil sample, and cannot strictly guarantee that the radial deformation in the vertical direction of the soil sample can meet the boundary conditions.

In the rigid confinement condition of method ②, point sensors are usually used to measure the radial pressure. On the one hand, there are errors in the radial stress measurement, and on the other hand, there is friction between the soil sample and the side wall of the pressure chamber, and the principal stress direction of the soil sample is deflected, so that The reliability of the measured static earth pressure coefficient has been questioned

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