Abstract: An indoor model test was conducted to study the erosion failure pattern, erosion height, and erosion velocity of the soil layer, considering three influencing factors: soil type, water inflow pressure, and water supply pipe diameter. The results showed that the soil type affected the form of erosion failure. Collapse cavities accumulated on top of the erosion zone in a sand layer, while the erosion zone in a clay layer maintained a temporary stability. Moreover, the gravelly sand layer exhibited a rearrangement of the soil particles into a "fine upper and coarse lower" layer. Increasing the water inflow pressure, and reducing the water supply pipe diameter substantially increased the erosion pressure on the damaged mouth. The overburdened surface transformed from a downward collapse failure to an upward hill failure. Based on the test similarity scale and erosion height curve, the erosion time for a damaged jet in a similar engineering environment could be estimated, providing a reference for the construction and maintenance of urban underground water-supply networks.

Key words: water supply pipe leakage, jet erosion, soil layer form, indoor model test