Shaking table tests on sliding characteristics and mechanism of liquefaction landslide of low-angle loess deposit in Shibeiyuan

Based on the field investigation, exploration and laboratory tests, the initiation mechanism of low-angle liquefaction sliding, geomorphologic formation characteristics, instability process and sliding mechanism of Shibeiyuan in Ningxia during the 1920 Haiyuan earthquake are studied by shaking table model tests. The results show that the low-angle liquefaction sliding of Shibeiyuan is the liquefaction one of the saturated sandy loess formation caused by the special stratum structure and high-intensity ground motion of the 1920 Haiyuan earthquake. The liquefaction sliding process includes three stages: initiation of liquefaction stage, ejected acceleration stage, flow slipping and accumulation stage. Finally, the liquefaction sliding is characterized by high-speed and long-distance flows. The results show that the initiation of liquefaction is the trigger mechanism of large-scale sliding. The seismic acceleration amplification at the peak value and the inertial ejection are the driving mechanism of liquefaction sliding at high speed and long distance. The special stratigraphic structure of the lower permeability aquifer at the bottom and the saturated sandy loess layer in the middle is the physical basis for the formation of large-scale liquefaction sliding with low angle. The difference of liquefied degree leads to that of transport velocity of soils in different layers and the stretching and pushing action, which is the reason for the wavy geomorphology with peaks and valleys. The research results have important reference value for the recognition of earthquake liquefaction and sliding disaster mechanism of low-angle loess stratum under strong earthquakes and the innovation of landslide prevention and control technology.