Seismic Response of the Rock-filled Cofferdam Slope under Earthquake Conditions Considering Hydraulic-mechanical Coupling Effect

Abstract

More and more hydropower projects have been implemented in the active earthquake zone in Western China. The cofferdam as the prophase works may encounter the earthquake to be damaged and seriously threat the construction and safety of the main project, thus the seismic response of the rock-filled cofferdam should be paid more attention in the process of hydropower construction. However, most large-scale rock-filled cofferdams are located on the deep randomly distributed layers which are very complex and less to be dealt, especially the filled materials of the cofferdams are very poor to be damaged under complex coupling environment. Considering the earthquake conditions and corresponding resulted hydro-mechanical coupling effect, 3-D hydro-mechanical coupling theory considering earthquake motion has been proposed to simulate the seismic response. And then, the cofferdam displacement, time histories of the represented variables have been compared between the coupling conditions and uncoupling conditions, indicating that the hydro-mechanical coupling effect caused by the earthquake should weaken the materials properties and enlarge the seepage pressure so as to expand the plasticity range and decrease the slope stability. Further comparison between the different ascending rate of the water level considering the same earthquake acceleration, it can be concluded that larger ascending rate of the water level results in greater displacement, indicating that the hydro-mechanical coupling effect caused by the earthquake cannot be ignored for research on the weir damaged. Therefore, rational anti-seepage measures and local reinforcement measures are the effective for the cofferdam seepage control and stability, and the strict construction control are ensured as the cofferdam safe cooperation.