Comprehensive Analysis Of Influencing Factors And Control Measures Of Land Subsidence In The Main Urban Areas Of Jiading New City

Land subsidence is an environmental geological phenomenon in which the subsidence of the ground surface leads to the loss of elevation,especially in the coastal urban areas with deep Quaternary strata.Affected by the comprehensive response of natural and human factors,land subsidence has the characteristics of slow evolution,long duration and complex cause mechanism.In China,land subsidence was first discovered and recorded in the central area of Shanghai.Although the land subsidence in the city center is now under preliminary control,considering the overall consideration of the national strategy for the integration of the Yangtze River Delta proposed in recent years and the overall urban planning of Shanghai during the 14 th Five-Year Plan about five new cities in Shanghai,this thesis selects Jiading New City as a typical area for the latest development of land subsidence based on double node.By carrying out single well and group wells pumping and stopping water pumping during outdoor deep foundation pit excavation,the test has found out that the micro-confined water and the first confined aquifer of the main shallow aquifer in the hydrogeology around the Metro Jia-Min Line to be constructed,when there is a hydraulic connection,the closer the distance to the pumping center is,the settlement will be larger,the soil will not settle when the pumping is stopped and the water level will return to the level before the test,the rebound amplitude will be about 30-40%,and the soil will undergo consolidation and settlement changes indicate that the effect of water pumping on land subsidence tends to decrease gradually ouside the test area.MIDAS GTS NX geotechnical engineering finite element software is used to simulate and analyze the influence of subway tunnel excavation and the generated static and dynamic loads on the settlement of surrounding buildings,horizontal steel reinforcement is adopted to reduce the displacement,and the result of analysis is that characteristics of the same type of buildings that are closer to the excavation tunnel,the greater the land subsidence is.Through the regression model and the AHP-SWOT models,the judgment matrix is constructed to realize the hierarchical ordering and structural analysis of the influencing factors of land subsidence.It is preliminarily judged that the dominant factor of land subsidence in Jiading New City is changing from the traditional exploitation of groundwater to engineering construction factors such as foundation pit excavation.At the same time,the weight calculation of factors affecting land subsidence is established,and based on the above data and conclusions,the risk analysis of land subsidence in Jiading New City is carried out,and prevention and control measures such as engineering technology and management are proposed to achieve the purpose of providing a basis for refined urban safety management.