Dynamic pore pressure of the bedding fault material within the basal layer and energy analysis based on the triaxial test

The Daguangbao landslide was triggered by the 2008 Wenchuan earthquake. The sliding zone formed in a bedding fault along which groundwater could be found to flow. The key factor of the landslide initiation is the strength change in the bedding fault under the earthquake effect, and the development of dynamic pore pressure is the root cause of the material strength of soil degradation. Therefore, a series of dynamic triaxial tests were conducted on the materials to examine the property of dynamic pore pressure. The results show that the dynamic pore pressure of the bedding fault material grows faster under the dynamic load, and the dynamic pore pressure increases faster when the cyclic shear stress ratio is greater. The dynamic pore pressure ratio is basically equal to the confining pressure when the strain reaches 5%, and the materials are liquefied. A stress model of a power function according to the relationship of the dynamic pore pressure ratio and cycle ratio is proposed. The response of pore water pressure can be described by using energy, revealing that the cyclic shear stress ratio has less effect on the relationship of the dynamic pore pressure ratio and cycle ratio. The confining pressure has a great influence on the relationship of the dynamic pore pressure ratio and cycle ratio. The theoretical energy model of dynamic pore pressure is further proposed.