关键词: 钙质砂, MICP, 动孔压, 动变形, 动强度, 纤维, SEM

Abstract: In this paper, the calcareous sand with carbon fiber was solidified by using microbial induced calcium carbonate precipitation(MICP) technology. Then the dynamic triaxial test, measurement of calcium carbonate content and SEM test were carried out to study the influence of fiber content on dynamic pore pressure, dynamic deformation and dynamic strength of bio-cemented calcareous sand under different dynamic stress levels as well as the micromechanism of fiber on MICP. The test results indicated that the calcium carbonate content of the solidified body increased with the increase of the fiber content, and the dynamic strength of the solidified body and the ability to resist deformation also increased, which indicated that the anti-liquefaction ability of the solidified body increased with the increase of fiber content. The development of dynamic pore pressure could be divided into four stages: initial development stage, steady growth stage, rapid growth stage and complete liquefaction stage. When the dynamic pore pressure developed close to the confining pressure, the solidification would be unstable. The fiber strengthens the MICP process through bridging action, with the increase of fiber content, bridging action was more obvious. At the same time, the spatial stress region formed by fiber between sand grains was larger, so the dynamic pore pressure and dynamic deformation development of solidified body became slower. The test results provide some reference for the improvement of calcareous sand foundation.

Key words: calcareous sand, MICP, dynamic pore pressure, dynamic deformation, dynamic strength, fiber, SEM,