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A Study on the Spatial-Temporal Evolution Regularity of the Deformation of a Foundation Pit in Soft Soil
(1 State Key Laboratory for Geomechanics & Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221008; 2 School of Mechanics & Civil Engineering, China University of Mining and Technology, Xuzhou 221008; 3 China Railway Construction & Investment Group Co. Ltd., Shenzhen 51800)
Abstract The geotechnical hazards caused by the excavation of foundation pits in soft soil are becoming increasingly prominent. In order to obtain the spatial-temporal evolution regularity of foundation pit deformation caused by excavation in soft soil, a 3D numerical model that takes into account the influence of silt layer creep properties and the concrete brace strength changes over time was built using FLAC3D for the Qianhaiwan Station foundation pit of Shenzhen Metro Line 11. Through modelling simulations, this paper studies and analyzes the spatial-temporal evolution regularity of the support structure deformation of a foundation pit, as well as the surface settlement and internal force of the support as it changes with excavation. The results show that: 1) the maximum displacement position of the foundation pit pile will move downward with excavation, and the pile displacement pattern will change from a "forward-shaped" one to a "bow-shaped" one; 2) the maximum pile displacement approximately exhibits a tendency of exponential decay with the passing of excavation time; 3) surface subsidences on both sides of the foundation pit present a "groove-shaped" form along the transversal direction with maximum settlement occuring 6.5 m away from the margin of the foundation pit, and this settlement value has a linear relationship with the excavation time.
Abstract：
The geotechnical hazards caused by the excavation of foundation pits in soft soil are becoming increasingly prominent. In order to obtain the spatial-temporal evolution regularity of foundation pit deformation caused by excavation in soft soil, a 3D numerical model that takes into account the influence of silt layer creep properties and the concrete brace strength changes over time was built using FLAC3D for the Qianhaiwan Station foundation pit of Shenzhen Metro Line 11. Through modelling simulations, this paper studies and analyzes the spatial-temporal evolution regularity of the support structure deformation of a foundation pit, as well as the surface settlement and internal force of the support as it changes with excavation. The results show that: 1) the maximum displacement position of the foundation pit pile will move downward with excavation, and the pile displacement pattern will change from a "forward-shaped" one to a "bow-shaped" one; 2) the maximum pile displacement approximately exhibits a tendency of exponential decay with the passing of excavation time; 3) surface subsidences on both sides of the foundation pit present a "groove-shaped" form along the transversal direction with maximum settlement occuring 6.5 m away from the margin of the foundation pit, and this settlement value has a linear relationship with the excavation time.
.A Study on the Spatial-Temporal Evolution Regularity of the Deformation of a Foundation Pit in Soft Soil[J] MODERN TUNNELLING TECHNOLOGY, 2016,V53(3): 82-90
2016, Vol. 53 