Characteristics of loess seismic subsidence and corresponding micro-zonation for the Fuping Country, Shaanxi

Typical loess generally shows the property of strong seismic subsidence due to its special microstructure characteristics. Fuping County which is located in the connection zone of Weihe Basin and Ordos Platform possesses complex seismic tectonic settings, high seismic fortification intensity, and widely distributed loess strata. Consequently, the risk of loess seismic subsidence is relatively high for the loess site of the region. In this paper, the regions of Fuping City and Fuping-Yanliang new area were chosen as the study area. The technical methods, such as data collection, field investigation, laboratory test, and theoretical analysis, were adopted to determine the seismic geological conditions of the region. The ground motion parameters with different transcendental probability levels were obtained by adopting the probability analysis method of seismic risk. The seismic subsidence properties of loess from various landforms and strata were studied based on a large number of dynamic triaxial tests. On this basis, Evaluate the seismic subsidence of loess sites under strong earthquakes in Fuping County. Under the condition of a probability of exceeding 10% in 50 years, mild and moderate seismic subsidence areas in the study area are distributed in the Fuyuan and Weihe secondary terraces. Under the condition of a probability of exceeding 2% in 50 years, the mild and moderate loess seismic subsidence areas in the study area are mainly distributed in the third to fourth level terraces of the Shichuan River, the floating plateau, and the second level terraces of the Wei River. Severe seismic subsidence areas are mainly distributed in the second level terraces of the Weihe River, the third to fourth level terraces of the Shichuan River, and the floating plateau. Based on the seismic subsidence level, the loess seismic subsidence sub regions of the study area were given at the 10% and 2% probability of exceedance in 50 years. Attention should be paid to this part of potential earthquake geological disaster in the design of prevention and foundation.