Analysis of mechanical properties and microscopic mechanism of EICP synergistic basalt fiber solidified calcareous sand

To address the challenges of low bearing capacity and excessive settlement in calcareous sand foundations, in this paper, the synergistic effect of enzyme-induced carbonate precipitation (EICP) and basalt fiber is proposed. Through the research and analysis of unconfined compressive strength, calcium carbonate production, triaxial shear, and microscopic tests, the optimum fiber content was finally determined to be 0.6%, and the grouting rounds were eight. When the grouting rounds are eight rounds and the basalt fiber content is optimal, the compressive strength and calcium carbonate production reach their peak values. The basalt fiber content and grouting rounds can significantly improve the shear strength of the sample; however, the stress-strain curve gradually transforms into strain softening. The change of pore water pressure further reveals the failure mode of the samples. The microscopic test results show that a stable interaction structure is formed between calcium carbonate precipitates, fibers, and sand particles, thereby significantly improving the curing effect. By combining EICP with basalt fiber, this study proposes a novel technical method for reinforcing calcareous sand foundations.