Variation characteristics of mineralizing reaction along seepage path in bio-grouting-reinforced silt

The inhomogeneity of reinforced soils is an important factor restricting the application of bio-grouting-reinforced soil technology. In order to investigate the variation characteristics of mineralizing reaction process along seepage path, one-dimensional bio-grouting tests are adopted to treat silt samples. Evolution of mineralizing reaction parameters such as microbial biomass, pH value and ion concentration, calcium carbonate production along the seepage direction are assessed for different seepage path lengths. The results show that the distribution of free bacterial biomass in the soils with different seepage path lengths has a normalized characteristic, and it decays exponentially with the increase of the relative seepage path length. The pH value, free calcium ion and ammonium ion concentration of the pore fluid change parabolicly with the increase of the relative seepage path length. The calcium carbonate production decreases with the increase of the relative seepage path length, is linearly positively correlated with the free bacterial biomass, and increases with the increase of the cementing solution concentration. A formula for predicting the distribution of calcium carbonate in the silt solidified by the bio-grouting is proposed based on the normalized relative seepage path length. The predicted values are in good agreement with the test results. The formula can be used to predict the reinforced effects of the bio-grouting-treated silt with different seepage path lengths. The research results may provide a reference for the design and construction of bio-grouting-reinforced silt ground.