Accident Analysis And Optimization Design Of A Soft Deep Foundation Pit In Nansha

In the future, Nansha will be the core regions of Guangzhou, which is located in the geometriccenter of Guangzhou, Hong Kong and Macao. The soft soil in this area mostly ismarine-terrigenous face. The conditions of geological and hydrologic geology are complex inNansha. Deep silt and mucky soil become the most critical problem of foundation engineeringand foundation pit in Nansha. This paper which considers engineering examples mainly deals inthe characteristics of soft soil in Nansha. It mainly analyze the selection of supporting structure,the reinforcement of supporting structure and the optimization design of supporting structure,provide experience for similar projects in Nansha. The main results are listed as follows:1. The rationale is calculated using the Lizheng software analyzes the slope. The resultsindicated that:(1) The overload resulting construction greatly reduces the safety factor of slopestability;(2) After the ground water infiltration slope topsoil, soil softened, reducing cohesion,slope instability and even tends to unsafe state;(3) Over excavation make supporting structurereduces the overall stability of the safety factor, which doesn’t meet the regulatory requirements.2. The optimized design of the gravity cement-soil walls indicated that:(1) When theretaining wall widths up to4.15m, the safety factor of overall stability reach a maximum of1.329;(2) Improve the gravity cement-soil walls embedded depth to11.0m, the each safetyfactor becomes more balanced;(3) When increase the thickness of the stabilized soil in passivezone, the maximum horizontal displacement of gravity cement-soil walls significantly reduced,and after adding the thickness exceeds4.0m stabilized;(4) Lower slope, dig up redundancy soil,which can effectively enhance the excavation stability.3. The double-row-piles walls and gravity cement-soil walls were compared. The resultsindicated that:(1) When considering the impact of the stabilized soil in passive zone, thedifference of safety factor of stability between double-row-piles walls and gravity cement-soilwalls is small;(2) Without considering the impact of the stabilized soil in passive zone, theoverturning stability and overall stability of the double-row-piles walls were significantly betterthan the gravity cement-soil walls, then the maximum horizontal displacement and moment andthe ground surface settlement were far less than the gravity cement-soil walls.