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 largescale 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.