Simulation and Stability Analysis of Gravel Deep Excavation under Heavy Rainfall Conditions

以海淀区第一有机资源中心环境提升项目基坑工程为背景，针对北京2023年七月特大暴雨作用下的深基坑变形问题，采用数值模拟和现场监测相结合的方法对强降雨条件下的基坑稳定性进行了系统研究，运用FLAC3D数值模拟软件分析了在设计支护状态下极端降雨前后两种工况下的基坑地表沉降与边坡水平位移及支护桩顶位移的演化规律；同时采用现场监测的方法记录了基坑在暴雨前后变形的基础数据。针对该基坑在强降雨情况下发生的位移做出分析，结果表示：强降雨作用下基坑处于不稳定状态且强降雨对基坑的影响主要体现在以下三个方面，地表沉降，支护桩侧移以及桩顶水平位移。模拟结果与实际测量数据相吻合，可以作为后期治理依据。Based on the background of the foundation pit engineering for environmental improvement at Haidian District’s First Organic Resource Center, this study systematically investigates the deformation characteristics of deep foundation pits under extreme rainfall conditions during the July 2023 heavy rainstorm in Beijing. Employing combined methods of numerical simulation and field monitoring, we employed FLAC3D numerical simulation software to analyze the evolution patterns of surface settlement, horizontal slope displacement, and support pile crown displacement in two distinct working conditions (pre-rainstorm design support state and post-extreme rainfall state). Concurrent field monitoring documented essential deformation data before and after precipitation. Analytical results demonstrate three primary manifestations of rainfall impact: amplified surface settlement, significant lateral displacement of support piles, and pronounced horizontal displacement at pile crowns. Validation shows good agreement between simulation results and field measurements, serving as a foundation for subsequent management measures.