Ponded infiltration and spatial–temporal prediction of the water content of silty mudstone

Ponded infiltration is very common in silty mudstone and has a great influence on the stability of related slopes, road cuttings, and tunnels. This paper aims to examine the infiltration performance of silty mudstone and predict the distribution of its water content under ponded conditions. By infiltration tests, the infiltration rate (i), cumulative infiltration (I), and their variations with the infiltration time (t) were obtained. Afterward, the variation of water content (w) with t and depth (s) was analyzed. The results show that the i value decreases with the increase in the degree of saturation, and the I value increases first significantly and then slightly during water infiltration. The entire w–t curve at any s is S-shaped, while the w–s curve at any t is full or half inverse-S-shaped. In addition, an equation was developed for the w–s prediction based on the simplified Gompertz curve model, and it was further extended to the spatial–temporal prediction model of water content. The evaluation results demonstrate that the spatial–temporal prediction model has high accuracy and reliability. The prediction model also indicates that the range of the infiltration-affected zone increases and the rate of increase slows down during water infiltration.