Abstract: Enzyme induced calcite precipitation (EICP) technology is applied to mineralize dispersed soil and improve dispersion resistance. The dispersed soil was sampled from a dam filler of reservoir in Hulunbuir, Inner Mongolia, and acted as parent soil during mineralization process. The dispersion of the soil sample before and after bio-mineralization was identified and evaluated by pinhole test, double hydrometer test and broken soil test. The results showed that the anti-dispersion ability of soil improved by bio-mineralization was significantly enhanced, especially by the microbial modifier prepared by urease solution. When the improved soil samples experienced 50, 180, 380 mm and 1 020 mm water heads in the pinhole test, the outflow water always remained clear and transparent, the water outlet was flat, and the size of the pinhole remained unchanged. The soil samples after the pinhole test were collected for broken soil test, and there was no colloidal particle dispersion during the test. During the double hydrometer test, it was found that the dispersity of soil samples improved by urease solution was less than 30%, which was reduced by about 50% compared to that of the unimproved dispersed soil, and the properties of soil sample changed from dispersive to non-dispersive. But for soil samples improved by microbial solution, the dispersity was 41.1%, which was 22% lower than that of the unimproved dispersed soil, the properties of soil sample changed from dispersive to transitional. The microbial modifier prepared by urease solution played a more adequate role in the mineralization process for fine-grained soil, and it was superior to the microbial modifier prepared by microbial solution in terms of the improvement of dispersed soil modification and the anti-dispersion ability improvement. In this paper, it is the first time that the bio-mineralization base on EICP technology was applied to the improvement of dispersed soil. This is an innovation combining green bio-mineralization technology with dispersed soil improvement in water conservancy damming engineering. It has a good application prospect in improving the dispersed soil of damming filler.

Key words: Bio-mineralization, Enzyme induced calcite precipitation (EICP) technology, dispersed soil, urease, pinhole test, dispersity