Resilient modulus of coarse-grained subgrade soil for heavy-haul railway: An experimental study

Large-scale dynamic triaxial tests under train-induced repeated load were conducted to study the variation of resilient modulus of the coarse-grained soil under different moisture contents, dynamic stress amplitudes, number of loading cycles and confining pressures. The results show that the state of specimens under the dynamic load can be divided into three categories: stable, critical and failure in accordance with the development trends of the accumulated plastic strain. For the saturated stable specimen, the resilient modulus tends to be stable at about 1000 cycles, while for the unsaturated stable specimen, the resilient modulus shows an increase trend with the increasing number of loading cycles. Resilient modulus increases with the increase of dynamic stress amplitude and confining pressure, but decreases with the increase of moisture content. The larger the amplitude of confining pressure and dynamic stress is, the more the resilient modulus decreases with the increase of moisture content.