Optimal Design Of Retaining Structure Of Narrow Foundation Pit Of Draw Water Project From Qiantang River

With the development of long distance projects such as the river training works, buried pipes and tunnels, more and more narrow excavations arise. In such excavation engineering, the ratio of the excavation width to the depth tends to be small. The width of the soil mass in passive zone is limited, so it’s unsuitable to use the classical Coulomb or Rankine earth pressure theory to calculate the passive earth pressure. However, the safety factor formula against overturning stability recommended by the current design code does not reflect the impact of pit width, resulting the same embedded depth of retaining wall for different widths of foundation pit, and the inner force and deformation results of the wall analyzed by the elastic foundation beam method cannot take the spatial effect of the narrow pit in account as well.In this study, a summary of the relevant research of deep excavation is presented. Based on the narrow excavation of the draw water project from the Qiantang River. The finite element analysis method and the PLAXIS geotechnical software are used to study the behavior of narrow excavation as following:1. Analysis of foundation pit deformation characteristics, types and control mechanisms.2. Considering the interaction between soil and retaining structure, the2D finite element models of narrow excavation are presented using PLAXIS software, for step-by-step excavation and construction.3. The internal force, the earth pressure of the retaining wall, the deformation of the soil and the safety factor against overturning stability with the embedded depth of the wall and the width of the excavation are studied.4. Numerical simulation and monitoring data were analyzed to verify the reliable and reasonable of the FEM model and parameter selection.