强震作用下饱和黄土液化特征试验研究

黄土液化是黄土地区的三大典型震害之一。针对海原大地震诱发的固原市石碑塬大规模低角度滑坡，基于室内饱和黄土的动力学试验，研究了此处饱和黄土的一系列液化特征和其孔压与应变的增长发展规律，及其围压和所受动应力对孔压发展规律的影响。结果表明:饱和黄土的液化应力比随动应力循环次数的增长逐渐减小，且饱和黄土一旦发生液化，其强度迅速丧失。动荷载作用下，击实试样的轴应变在2 %之前，孔压匀速增长，轴应变增长缓慢；轴应变达2 %以后，动应力开始有部分消减，轴应变开始加速增长，故2 %应变可视为击实试样液化的一个结构强度临界

Experimental Study on Characteristics of Saturated Loess Liquefaction under Action of Strong Earthquake

Loess liquefaction is one of the typical earthquake damages in loess regions. In relation to the large-scale low-angle landslide in Shibeiyuan, Guyuan City, which was induced by Haiyuan Earthquake, this paper, based on laboratory dynamics tests on saturated loess, studied liquefaction characteristic of the saturated loess, the law of how its pore pressure and strain develop, and also how this law is influenced by the confining pressure and dynamic stress. The results show that as increase of the number of cycles of the dynamic stress, the saturated loess has the decreased liquefaction stress ratio, and will lose its strength rapidly once the liquefaction arises. Under the action of dynamic loading, the compaction test specimen, when its axial strain is less than 2 %, has evenly increased pore pressure and slowly increased axial strain; while the axial strain is more than 2 %, the dynamic stress will reduced partly and the axial strain will accelerate its increase. Therefore the strain of 2 % could be deemed as a critical point of structural strength in case of liquefaction of compaction test specimen, and the maximum pore pressure does not reach an effective confining pressure completely.