Quantitative analysis of pipeline leakage conditions on ground collapse in sandy soils

Ground collapse poses a significant challenge to urban infrastructure safety and sustainable development, often resulting in severe economic losses and threats to public safety. Damage to underground pipelines is recognized as one of the primary triggers of such failures. Focusing on sandy soil conditions in Guangzhou, a series of laboratory model tests were conducted to simulate the full evolution process of subsurface cavity formation and subsequent ground collapse induced by pipeline leakage. The effects of key factors, including pipeline burial depth, defect size and internal flow velocity, on the soil erosion process were systematically investigated. The results show that leakage from damaged pipelines induces outward seepage flow, leading to progressive erosion of surrounding soil and particle migration. This process results in the gradual formation of arch-shaped underground cavities, which continuously expand with ongoing soil loss. Collapse occurs when the soil arch can no longer sustain its self-weight and the overlying load, ultimately forming characteristic hourglass-shaped erosion cavity. Parametric analysis shows that increasing burial depth, reducing defect size and lowering the flow velocity can effectively decrease the scale of ground collapse and shorten the evolution time of subsurface cavities, thereby mitigating collapse risk. The findings provide a quantitative basis for understanding the mechanisms of pipeline leakage-induced ground collapse and offer theoretical guidance and technical support for the prevention and mitigation of urban subsidence hazards.