Analysis On Seepage And Piping Of Secant Piles Exterior Protected Construction In Silt-sand Soil

The properties of construction determine the complexity of hydraulic condition of deep foundation pit. Many engineering practices show that seepage is the important cause of foundation pit accident. Secant piles are new exterior-protected construction, SHENZHEN Metro first-stage construction, NANJING Metro Line 1, TIANJIN Metro Line 3, HANGZHOU Metro Line 1 all adopted secant piles exterior-protected construction. This retaining structure is easy to initiate piping as a result of secant piles bitten deficiently. However, the relevant theoretical study lags far behind the engineering practice, so it is an important research subject to study the properties of seepage and piping of secant piles exterior-protected construction in silt-sand soils.To provide technical supports for the design of deep foundation pit and the practice engineering, in this paper, the seepage, leakage, piping of deep foundation pit in silt-sand soils are systematically studied on the basis of ABAQUS.Firstly, HANGZHOU Metro Line 1 QIUTAO Road Station deep excavation engineering is introduced;Secondly, analyze and simulate seepage property of it as a result of dewatering and simulate leakage of secant piles due to bit deficiently;Finally, in the process of excavation, seepage field change gradually, leakage developed into piping. This paper also simulated the process of piping. This paper shows that it is important to construction and safety of deep foundation pit to simulate the property of seepage and piping and get the law of watertable and ground settlement by numerical method.