Study on the Internal Mechanics and Energy Characteristics of Soil under Different Failure Modes

Abstract

Under uniaxial compression, the soil mass may be subjected to transverse tensile splitting or swelling failure. This failure is caused by the tensile stress in the soil; that is, part of the vertical stress is converted into lateral stress. In order to investigate the factors that influence the stress transfer phenomenon, the failure mode of the soil mass can be predicted more accurately, and the internal force of the soil mass can be analyzed. This paper begins with the definition of the stress conversion coefficient and measures it by combining macroscopic mechanical properties with microscopic structure analyses. By carrying out a uniaxial compression test on a large soil sample, an equivalent tensile test was carried out according to the equivalent transverse displacement measured using the S-type tension sensor in order to explore the change law of the stress conversion coefficient. The arrangement and distribution of pores and particles at different positions in the samples before and after compression were further observed and analyzed using the SEM test to explore the formation mechanism of the stress transition phenomenon, and the following research results were obtained: (1) The stress conversion coefficient of the soil under compression is not invariable. An increase in the loading rate and a decrease in water content cause brittleness, and the stress conversion coefficient of the soil decreases. (2) Shear failure is more likely to occur in large samples of brittle soils under uniaxial compression. (3) The tensile stress in the compressed soil is caused by the invasion and extrusion of soil particles.