Landslide risk evaluation: rainfall and blast-induced potential soil landsides in an expressway area underneath a railway tunnel, Guangzhou, China

The construction of expressways in soil and their interaction with railway tunnelling blast excavation faces risks due to limitations on safety vibration velocity regulation on soil landslides. This paper reports on a potential soil landslide coupled with rainfall and blast in an expressway area underneath a railway tunnel in Guangzhou, China. Field monitoring was conducted to obtain the landslide’s geometric features, magnitude, crack distribution, and potential sliding surface. Using the unbalanced force transfer coefficient method, a mechanical model with normal and rainfall conditions was employed to analyse slope stability. Numerical modelling was employed to study the dynamic features of soil slope induced by the blast effect. The triggering factors on topography, tectonics, lithology, rainfall, and blast effects were discussed in detail. A slope mitigation method was proposed, and 6-month surface deformation monitoring was conducted to examine the mitigation effect. The novel results show that the slope was unstable under coupled effect on rainfall and blast conditions, with a potential push-type soil landslide from the top-level slide to the second level. The safety regulation velocity of 3 cm/s for rock slope is too large for safety control on soil slope.