黄土震陷性深度特征的试验研究  

Characteristics of loess seismic subsidence with depth under cyclic loading

作　　者：徐舜华[1,2] 王兰民[2] 孙军杰[1,2] 吴志坚[2] 

机构地区：[1]兰州大学土木工程与力学学院,兰州730000 [2]中国地震局兰州地震研究所,兰州730000

出　　处：《岩土力学》2010年第11期3397-3403,共7页Rock and Soil Mechanics

基　　金：国家自然科学基金(No50379049);中国地震局预测研究所基本业务项目(No2009A18)

摘　　要：黄土震陷是地震发生时黄土地区发生的一种灾害。以典型马兰黄土(Q3)作为研究对象,对5组不同深度的原状黄土试样进行室内动三轴震陷试验,研究了该场地黄土震陷性随深度的变化特征。研究结果表明,(1)在天然含水率或是增湿、减湿情况下,黄土震陷深度曲线随动应力的增加均经历了一个从平稳、快速、再收敛至最大震陷深度的发展过程;(2)黄土震陷深度曲线的发展阶段动应力区间不尽相同,随着含水率的增加,黄土震陷快速发展期的动应力区间在变窄,最小动应力值变小,含水率20%条件下比5%最小动应力值可降低30%;(3)典型马兰黄土存在一个最大震陷深度,其最大震陷深度不受动应力、含水率影响,含水率仅能够降低达到最大震陷深度时最小动应力,加速黄土震陷深度的发展进程。在动应力不断增加的情况下,最终的黄土震陷深度曲线收敛于最大震陷深度,本次实验黄土场地的最大震陷深度约为15.5m。Loess seismic subsidence is a type of disaster when the earthquake occurred in a loess area.The characteristics of loess seismic subsidence with depth is studied by indoor dynamic triaxial test of 5 groups of original Malan loess Q3 samples in different depths.The results show that：（1） In terms of natural water contend,humidification or dehumidification,the depth of the loess seismic subsidence,with the increase dynamic stress,has a process of from smooth to rapid lowering,and then converging to the maximum depth of seismic subsidence.（2） Dynamic stress intervals are different corresponding to stages,interval in rapid lowering stage becoming narrow;the minimum dynamic stress shrinking with increase of water content;and the minimum dynamic stress can lower by 30% in term of 20% comparing to 5%.（3） The maximum depth of loess seismic subsidence is found and it is not affected by the dynamic stress and water content.Only the water content is able to reduce minimum dynamic stress when reaching maximum depth of the seismic subsidence and speeds up the development process.At last,the loess seismic subsidence curves of the depth converging to the maximum of depth of seismic subsidence with increasing of the dynamic stress;and in this experiment the maximum depth is 15.5 m.

关 键 词：黄土震陷深度特征 最大震陷深度 含水率 动应力 增湿 减湿 

分 类 号：TU444[建筑科学—岩土工程]