CRITICAL INFLUENCE PARAMETERS AND MAGNITUDE ESTIMATION OF DYNAMIC RESIDUAL STRAIN OF UNSATURATED LOESS
SUN Junjie1，2，3，XU Shunhua1，2，3，WANG Lanmin1，2，3，WANG Jun1，2，3，TIAN Wentong1
(1. Lanzhou Institute of Seismology，China Earthquake Administration，Lanzhou，Gansu 730000，China；
2. Key Laboratory of Loess Earthquake Engineering，China Earthquake Administration，Lanzhou，Gansu 730000，China；
3. Geotechnical Disaster Prevention Engineering Technology Research Center of Gansu Province，Lanzhou，Gansu 730000，China)
Abstract：By analyzing the physical process and mechanism of the dynamic residual strain of unsaturated loess，critical influence parameters are investigated. By contrast with laboratory data of unsaturated loess specimens under dynamic/static triaxial tests，consequently，a magnitude estimation method with two individual formulas is proposed for the dynamic residual strain of nature loess. The analysis results show that the dynamic residual strain of unsaturated loess could be described as a consolidation response of generalized solid-phase-media of loess mass under external dynamic loads. Meanwhile，critical parameters influencing the dynamic residual strain of unsaturated loess include two aspects，which are the strength and volume characteristics of the generalized solid-phase-media and the external dynamic loads features，respectively. For above-mentioned critical characteristics，the strength could be figured by cohesion and internal friction angle，both expediently obtained through laboratory geotechnical tests，while the volume could be described by void ratio，which reflects the under-compacted status of loess mass. Generally，the former shows the endurance capacity of loess to resist external dynamic loads and the latter describes the settlement capacity of loess under an external dynamic load. In the analysis of magnitude estimation method for dynamic residual strain of unsaturated loess proposed here，the results of physical mechanism and critical influence parameters are considered comprehensively. It will be helpful，therefore，to establish a reasonable and practical constitutive model for plastic deformation of unsaturated loess under dynamic/static loading.
2012, Vol. 31 
