Study On Calculation And Simulation Of Dewatering Permeability In A Deep Foundation Pit

This article is based on engineering practice,drawing on previous research results and research theories,taking a deep foundation pit dewatering field test of a resettlement housing project as the research object,expounds the basic theory of groundwater dynamics and hydrogeology related to foundation pit dewatering design Parameters and design models.Starting from the main methods of deep foundation pit dewatering,the applicable conditions of various foundation pit dewatering methods are introduced,the main factors affecting the quality of foundation pit dewatering construction are analyzed and summarized,and the impact on the foundation pit is calculated through single well dewatering and group well dewatering field test The hydrogeological parameters of precipitation are simulated based on mathematical models and software Modflow and compared with actual results to design an economical and reasonable precipitation construction plan to achieve a win-win situation for economic and ecological benefits.The main research contents are as follows:(1)A general analysis of the development status and development trend of deep foundation pit dewatering,expounding the basic laws of groundwater classification and movement,explaining the hydrogeological parameters that affect foundation pit dewatering,and exploring the methods and scope of application of deep foundation pit dewatering.(2)According to the hydrogeological conditions of the project,a single well precipitation field test was carried out,and the hydrogeological parameters were calculated using the data obtained from the single well precipitation field test.After preliminary calculations,the single well’s precipitation influence radius R was about 55 m,and the penetration The coefficient K is about 0.46m/d.According to the numerical calculation results,it is proposed to adopt the tube well dewatering method for foundation pit dewatering.(3)On the basis of single well dewatering,field test of group well dewatering was carried out,and numerical calculation was carried out by using the "big well method".After calculation,the permeability coefficient K of group well precipitation is 0.40m/d,and the radius of influence of precipitation is about 60 m.According to the test results of group well precipitation,the Boussinesq equation was introduced to establish a mathematical model,and Modflow software was used to simulate,and the data results simulated by the software were compared with the actual monitoring values.The error was small,which proved the accuracy of the test model.,Which shows that Modflow software can simulate the foundation pit dewatering project and meet the design accuracy requirements.(4)In the initial stage of project planning,considering the hydrogeological conditions,it is proposed to adopt a combination method of water-stop curtain and tube well for dewatering in foundation pits.Through the field test of single well and group well dewatering,the design and construction plan of foundation pit dewatering were optimized,and its rationality and effectiveness were analyzed.The three aspects of safety benefit,economic benefit,environmental benefit and the water-stop curtain The experiment was conducted to compare and analyze,and to verify the economy and feasibility of the tube well dewatering and water collection open drainage scheme.At the same time,establish a foundation pit settlement prediction and monitoring system,study the impact of foundation pit precipitation on the surrounding ecological environment,and provide relevant experience data for similar precipitation projects in the future.