关键词: 钙质砂, MICP, 单颗粒破碎, Weibull分布

Abstract: As a special geotechnical material, calcareous sand is easy to break under low pressure. In recent years, microbially induced calcite precipitation (MICP) technology has gained wide attention and recognition, which can be used to improve the crushing characteristics of calcareous sand. In this paper, the single particle crushing test of calcareous sand particles before and after MICP was carried out through two aspects of laboratory test and discrete element model simulation, respectively. The effects of MICP on the crushing behavior of calcareous sand particles was investigated through Weibull distribution and SEM scanning. The results show that the survival probability curve and the value of Weibull modulus m obtained by discrete element model simulation are in good agreement with the experimental results, which verifies the validity of the numerical model. Compared with the laboratory test, numerical simulation can accurately reflect the crack distribution and crushing process of the particle as well as studying the situation before and after MICP for the same particle, which makes up the deficiency of the laboratory test. However, it depends on the selection of model parameters. After MICP, calcareous sand particles have obvious calcite crystal formation on its surface, and the surface and internal pores of the particles are wrapped and filled to a certain extent, respectively, resulting in significantly enhanced particle crushing strength and greatly reduced discreteness, and the crushing mode changes from “multi-peaks type” to “single-peak type”, as well as local crack reduction mainly surface abrasion and direct generation of through-wall crack.

Key words: calcareous sand, MICP, single particle crushing, Weibull distribution