Research On The Influence And Control Technology Of Water-rich Deep Foundation Pit Excavation On Adjacent Pipelines And Buildings

Urban renewal and renovation is a key research field of the country’s "14th Five-Year Plan",and its core key issues are the renovation of old urban areas and environmental safety issues,that is,how to avoid or reduce the impact of engineering construction on the safety of the surrounding environment,which requires continuous improvement and improvement.Existing construction techniques and methods,and create new construction methods.This paper studies the safety impact of deep foundation pit excavation on surrounding buildings and pipelines in an old urban water-rich area of Xuzhou,develops a new water stop device,and optimizes the deep foundation pit support and precipitation scheme.The main research contents are as follows:(1)According to the engineering geological characteristics of the foundation pit and the surrounding environmental buildings and municipal facilities,the numerical simulation analysis method is used to systematically simulate and study the variation trend of the displacement field induced by the foundation pit precipitation and excavation,and combined with the characteristics of the foundation pit support structure the deformation and failure mechanism of the surrounding buildings and pipelines is revealed.On this basis,the safety status of the surrounding buildings and pipelines is evaluated,and the safety risk is determined.(2)In order to ensure the safety of surrounding buildings and pipelines,the optimized support scheme of water-stop and SMW construction method piles +prestressed anchor cables was selected on the north side of the foundation pit through comprehensive comparison.Aiming at the problem that the pipes are easy to block when pumping water in the silt layer,a new type of artificial water filtering pipe well technology was developed,and a comprehensive scheme of using pneumatic dewatering equipment to assist the pipe well point dewatering in the periphery of the foundation pit and artificial water filtering pipe wells to assist the open drainage in the pit was designed.Aiming at the problem of groundwater seepage during the construction of the anchor cable,the patented technology "Anchor Cable Orifice Water Stopping Device" was developed to solve the safety problem during construction.(3)According to the optimized foundation pit support and dewatering scheme,a numerical calculation model was designed,the impact of the foundation pit excavation construction process on the surrounding environment was simulated and analyzed,and an on-site monitoring network for the surrounding environment of the foundation pit was designed and arranged.The real-time curve of surrounding environment changes such as horizontal displacement of supporting structure,ground settlement,settlement of adjacent buildings and pipelines during the process.Based on the comparison and verification of field measured data and numerical simulation results,it can provide reference and reference for similar projects.