Experimental study on strain development of liquefaction of saturated undisturbed Q₃ loess

Based on the dynamic triaxial tests, taking undisturbed Q₃ loess in Guyuan Stele-tableland of Ningxia for an example, the trend of the development of axial strain in the liquefaction process is studied. The change rules of dynamic stress and dynamic strain hysteresis curve depending on the vibration frequency (intensity) and the relationship among axial strain, stress path and pore pressure of the saturated Q₃ loess at mild, moderate, complete liquefaction stages are analyzed. The results show that, with the increase of vibration frequency, saturated Q₃ loess gets into a special stress state. Its structure changes, hysteresis curve presents different characteristics in different liquid levels. The strain development closely relates with the stress path. When the loess gets into the state transition stage, the strain and pore pressure exhibit a big development. However the residual pore pressure and residual strain development of the loess are different. The residual pore pressure has a finite value, but the residual strain keeps on developing. The amplitudes of pore pressure and axial strain both increase with the vibration frequency in a monotonic function.