Study on the disaster mechanism and prevention technology of embankment slip-collapse after extreme rainfall in the loess area

This study investigates railway embankment slip-collapse disasters triggered by July 2021 extreme rainfall in Zhengzhou, China, through field investigations, in-situ tests, laboratory tests, field monitoring, and numerical simulations. The research results indicate that: (1) Zhengzhou loess experiences accelerated strength degradation when moisture content exceeds plastic limit, with shear modulus, cohesion, and internal friction angle decreasing rapidly beyond this threshold. (2) Embankment slip-collapse, a geohazard characterized by shallow failures in slope surfaces, is primarily triggered by hydro-mechanical coupling under extreme rainfall, with deformation severity controlled by infiltration intensity. (3) Three stages of slope stability division criteria are proposed, namely metastable zone, critical instability zone, and instability zone. The critical threshold of moisture content of 20.71% under these conditions provides a quantifiable benchmark for early warning systems targeting surface collapse prevention. (4) A steel grouting pipe reinforcement technique demonstrated effective stabilization, achieving 251 kN anchoring force and improved stratum integrity. Surface wave tests, numerical simulations, and field monitoring confirmed significant displacement control and enhanced slope stability under extreme rainfall conditions. The research results provide critical insights for transportation infrastructure protection against extreme rainfall conditions.