Experimental investigation of the dynamic behavior of frozen clay from the Beiluhe subgrade along the QTR

The dynamic behavior of frozen clay obtained from the Beiluhe permafrost subgrade along the Qinghai-Tibet Railway (QTR) was investigated through cryo-dynamic triaxial experiments. The effects of several key factors, including temperature, moisture content, frequency and confining pressure on the dynamic behavior, were analyzed. It was found that a hyperbolic model could describe the dynamic behavior of the frozen clay well. The maximum dynamic shear modulus of the frozen soil decreases as the temperature rises and as the confining pressure decreases; the reference shear strain magnitude decreases as the temperature and confining pressure increase and as the moisture content decreases; the maximum damping ratio increases as the temperature, frequency and confining pressure increase and as the moisture content decreases. There exists a critical moisture content (around 18%) that maximizes the dynamic shear modulus; at the critical frequency (about 6 Hz), the dynamic shear modulus is at its maximum, and the reference shear strain magnitude and the damping ratio attenuation exponent are at their respective minima. Moreover, functions were proposed to quantitatively describe the relationship between frozen clay dynamic parameters and various influencing factors. (C) 2011 Elsevier B.V. All rights reserved.