陕西富平黄土震陷特性及震陷小区划

典型黄土由于其特殊的大孔隙架空结构特征，在强震作用下具有强烈的震陷性。陕西富平县地处渭河盆地和鄂尔多斯地台的连接带，区内地震构造背景复杂，黄土分布广泛，黄土场地的震陷危险性较高。文章以富平县城市总体规划建设用地和富阎新区规划范围为研究区，通过资料收集、野外调研、室内试验和理论分析等方法，确定研究区的地震工程地质条件，采用地震危险性概率分析方法确定研究区不同超越概率水平的地震动参数，基于大量黄土动三轴试验确定区内不同地貌单元及不同地层黄土的震陷特性。在此基础上，对富平县强震作用下黄土场地的震陷进行评价，50 年超越概率10%条件下，研究区内轻微、中等震陷区分布于浮塬和渭河二级阶地。50年超越概率2%条件下，研究区内轻微及中等黄土震陷区主要分布在石川河三—四级阶地、浮塬和渭河二级阶地。严重震陷区主要分布在渭河二级阶地、石川河三—四级阶地和浮塬。根据震陷等级给出了研究区50年超越概率10%和2%水平下的黄土震陷小区划。研究结果可为富平县的防震减灾工作提供科学依据。

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.