In recent years, soil solidification by EICP method is a green and environmentally friendly foundation treatment technology that has become popular in the field of geotechnical engineering. Compared with the traditional chemical induction method and the MICP method, the EICP method is not easily restricted by environmental factors associated with engineering geological problems and is green and environmentally friendly with lower cost. In this paper, a study was carried out to improve the seepage-mechanical properties of sandy soils by the EICP method. First, soybean urease solution extraction and its performance optimization methods were explored. Tests were conducted to compare urease extraction and detect activity. The activity of urease was 7.1% higher in deionized water than Laoshan mineral water. Second, the EICP grouting mineralization test was performed by using the carbon fiber reinforcement method. The CaCO3 content, unconfined compressive strength, porosity, permeability and other indicators of the sandy soil were systematically analyzed, and microscopic tests were conducted. The test results showed that after carbon fibers were added to the sand, the mineralization effect of EICP led to the precipitation of CaCO3 that adhered to the surfaces of sand grains and fibers and filled and cemented the pores between sand grains, which improved the integrity of the spatial structure and formed a stable solid sand-fiber monolithic composite structure. When the carbon fiber content was 1.2%, all aspects of performance were optimum. The above test results showed that the carbon fiber-based EICP mineralization method could effectively inhibit the brittle failure and improve the permeability and mechanical properties of sandy soil. This method has good application prospects and development potential for use in engineering geology.

Carbon fiber; sandy soil; urease-induced carbonate precipitation; performance optimization; permeability-mechanical properties