Biogrouting for seepage control for rock joints

Grouting has been used frequently as a countermeasure of seepage control for underground construction. Conventional grouting techniques including cement grouting and chemical grouting can be used for seepage control for underground construction in rock when relative large joints are present. However, the high viscosity and large particle size of grouting material makes the grouting materials difficult to permeate into fine cracks. A novel biogrouting technique which employs biocement as the basic grouting material is presented in this paper. Laboratory experiments for use of biogrout to seal the interfaces between 18 pieces of horizontally laid granite slabs were carried out. The results of hydraulic pumping tests show that the seepage rate through the interfaces of the 18 pieces of granite slabs reduced by 1000 folds. A numerical analysis of the biogrouting process were also conducted to simulate the biocementation process and its pattern on the granite sheets. A comparison of the experimental data and the simulation results were made. Factors controlling the biogrouting process are discussed.