Method for testing change rule of microstructure in soil stretching process

Abstract

The invention discloses a method for testing a change rule of a microstructure in a soil stretching process. The method comprises the steps of (1) compacting a soil body in a die, manufacturing a soil body sample with two cylindrical holding ends at two ends and a cube stretching section in the middle, disassembling the die and removing the surface of an observation side to expose a fresh side of the sample; (2) fixing two holding ends of the soil body sample in two stretching clamps which are adaptive to the holding ends in size; (3) calibrating a stretching device, then setting a loading rate and beginning to apply continuous stretching load; (4) collecting images of detail structures of the soil body under different stress states; (5) fusing and splicing the collected images; and (6) extracting parameters of the microstructure with processed images to perform quantitative analysis. According to the method, through the observation and the later quantitative analysis of the soil body detail structures in the stretching process, analysis of a tensile fracture mechanism of the soil body and building of a tensile fracture criterion are facilitated.

Description

technical field [0001] The invention relates to a test method in geotechnical engineering, in particular to a test method for the change law of mesoscopic structure of soil during stretching. Background technique [0002] In the field of rock and soil, the failure of rock and soil includes compressive shear failure and tensile failure. In recent decades, the research on the compressive shear properties of soil has been very mature, but the research on tensile failure of soil is still Stagnant in the preliminary stage, this is mainly due to the low tensile strength of the soil relative to its shear strength, which is often neglected. However, the tensile failure of the soil often directly or indirectly leads to the instability or destruction of the geotechnical structure, such as the collapse of the upper structure caused by the excavation of the underground structure, the landslide of the soil slope under the external force such as rainfall, and the earth and rock The premi...

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Problems solved by technology

[0003] The current research on the tensile properties of soil is mainly to test its tensile strength at the macro level through direct or indirect test methods, and the influence of dry density, moisture content and other indicators on the tensile strength, and there

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