Study on the Long-term Dewatering Disturbance Pattern of Clayey Silt Composite Layer in Water-Rich Areas

Abstract

The clayey silt composite layer is widely distributed in the Central Plains of China, especially in the eastern new urban area of Zhengzhou. The stratigraphic structure is generally a multi-layer system interbedded with clayey soil, silt, and fine silty sand, predominantly composed of clayey soil. The thickness of a single clayey soil layer can reach up to 68m. This considerable thickness implies that the creep process during foundation pit dewatering will persist continuously. The main structure of a metro station in the Zhengzhou Eastern Area is adjacent to high-speed railway bridge piles. Based on a comprehensive understanding of the engineering geological conditions of the study area and combined with monitoring data, this paper establishes a three-dimensional numerical model using ABAQUS finite element simulation software. The disturbance law of the clayey silt composite layer under long-term dewatering conditions and the impact of long-term dewatering on high-speed railway bridge piles are derived. The results show that long-term foundation pit dewatering forms a dewatering funnel-shaped settlement curve centered on the dewatering wells, which expands over time. The settlement impact is highest near the dewatering wells. Long-term dewatering affects nearby high-speed railway bridge piles, and pier settlement is very sensitive to the water level drawdown. Therefore, it is recommended that the pit water-stop curtain on the side adjacent to the high-speed railway be constructed as a double row of water-stop piles with increased length.