Study on the Effect of Drainage Pipeline Leakage on Soil Density Change Rate

Frequent road collapses caused by seepage from buried pipelines present a significant risk to the safety of urban residents and their property. The soil density of soil is a crucial parameter that influences the shear strength and bearing capacity of subgrade soil. Existing studies have extensively investigated the seepage theory of soil–water interaction. While a comparative analysis revealed that pipeline water leakage constitutes a mechanical fluid flow problem in porous media within a seepage field, the variation characteristics of soil density during the process of pipeline water leakage have been overlooked. Neglecting the density changes caused by seepage erosion can easily lead to an underestimation of the sudden effect of soil instability, thereby increasing the probability of sudden road collapse. Therefore, this paper addresses the issue of pipeline leakage–induced road collapse by establishing a model for the rate of change of soil density affected by seepage erosion. The effectiveness of the model is validated through physical model tests simulating road collapse induced by pipeline leakage. Furthermore, we examined the evolution of soil density during water seepage erosion leading to road collapse and analyzed the patterns of the density change rate in response to increasing water leakage. The research study findings demonstrate a high Pearson correlation coefficient (>0.97) between the calculated theoretical soil density change rate and the values measured from physical experiments, thereby confirming the validity of the mathematical model. These results provide critical data support for monitoring and preventing road collapse disasters. The progression of soil density from pipeline seepage to road collapse traverses through three stages: erosion immersion, erosion to voids, and erosion to collapse. The most significant modification in soil density occurred during the erosion to cavity stage, with soil loss constituting 71% of the total discharged mass. When the soil density change rate falls below the critical threshold, underground cavities emerge on the road, altering the compactness of the soil structure. These results provide critical data support for monitoring and preventing road collapse disasters.