Investigation of a loess-mudstone landslide and the induced structural damage in a high-speed railway tunnel

This paper presents a landslide that occurred in loess hills resulting in structural damage to the Zhangjiazhuang tunnel of the Lanzhou–Xinjiang high-speed railway line. The characteristics of tunnel deformation and structural damage are provided in detail. To ensure future safety of the tunnel, investigations consisting of field reconnaissance, borehole investigations, seismic activity and rainfall records analysis, and numerical simulations were conducted to identify the regional geology and landslide characteristics. Using these investigations, the probable formation mechanism of this sliding failure is determined to be (i) an ancient groove that provides a natural slip bed leading to stress concentrations and dislocation failure at the back of the slope; (ii) seepage channels that are well-developed on this loess hillslope, through which an extreme rainfall event 6 months prior to the landslide saturated the strata materials; and (iii) finally, the limit state of the materials is reached in an earthquake under undrained condition, and the landslide is triggered. The findings presented in this paper can provide a reference for the control and treatment of landslides in loess areas.