Seepage–damage coupling study of the stability of water-filled dump slope

The stability of water-filled dump slope has been one significant geotechnical engineering problem that needs to be urgently resolved. The coupling effects of seepage and damage on the dump slope are critically important for stability analysis. In this paper, a seepage–damage coupled mathematical model is developed for fractured coal rock mass, and the permeability tensor effects from the fracture damage of coal rock mass are investigated. Numerical simulations are conducted for Dongming and Heidaigou dump slope on the stability of water-filled dump slope under the coupling effects of seepage and damage. Numerical results show that the high pore pressure can reduce the positive pressure of the sliding surface and the friction, and can lead to the strength loss of water-filled coal rock mass. It is also demonstrated that with the propagation of the slope crack, the pore pressure gradually dissipate to larger areas, and approaches the slope table. This will result in the further damage of the table rock of slope and the decrease of support force, has a serious impact on the overall slope stability of the system. With the development of seepage, the opened cracks increase gradually. The water pressure not only has restructured the fracture network of coal rock, but also has a huge impact on the main fracture deformation. It is demonstrated that if pore water pressure is difficult to dissipate, effective stress decreases and weak surface increases, and this further leads to instability of coal rock slope. The results also reveal that it is easy to cut out at the foot of the slope. Two failure models of “arc” or “located-sliding” are observed. The numerical results further reveal the percolation mechanism of the softening of coal rock slope.