Slope stability of underwater fill embankment in mountainous area

During construction of underwater embankment in mountainous area, there will be a weak layer between the embankment and the original mountain, which leads to the slope stability problem, because it is impossible to clear the surface and repair the slope of the original mountain below the water level. Based on the section of the Qianhuang expressway in the bay area of Zhejiang province, we carry out the numerical simulation of underwater embankment by using the finite element software GeoStudio and analyze the influence of the weak layer between submerged embankment and mountain as well as the variation of water level on the embankment slope stability. The results show that the changes of the thickness, the mechanical parameters, the relative position of the weak layer and the variation of water level have a certain impact on the stability of the embankment slope. With increase of the thickness of weak layer, the stability of the embankment slope decreases. With the continuous upward movement of the position of the weak layer, the stability coefficient of the embankment slope firstly decreases rapidly and then slows down. When there is a weak layer inside the embankment, the seepage force has a more obvious influence on the stability of the embankment slope. And the effect of water level change on the overall stability in the presence of weak layer is significantly different from that in the absence of weak layer.