Research On The Influence And Protection Of The Whole Life Cycle Of Large Diameter Pile Foundation Of Urban Viaducts On Shield Tunnels Adjacent To Metro

With the rapid development of construction in urban transportation infrastructure,urban transportation networks show a continuously increasing expansion trend.In the process of gradually forming a multi-layer urban transportation network,it is inevitable to encounter the problem of interaction of adjacent lines.As the two indispensable components of the urban transportation infrastructure,the interaction effect of the viaduct and subway should be paid more attention.In this research,the North Park Elevated Expressway,and its western adjacent rail transit R1 line was selected as the subject.In this thesis,the entire life span of the viaduct was divided into three phases: the construction of the viaduct pile foundation rotary excavation,the construction of the viaduct pile foundation,and the cap and the construction of the viaduct main structure.Theoretic analysis,numerical simulation,and other methods were used to study the impact of the entire life of the viaduct pile foundation on the adjacent subway shield tunnel.The main content and results of the thesis are as followed:Firstly,comparing and selecting the calculation method of the large-diameter pile foundation settlement of the viaduct,and carrying out the theoretical analysis of the pile foundation settlement of the viaduct.Based on the shear displacement method,the formula of the influence of the pile foundation settlement on the displacement of the subway shield tunnel was summarized.Taking the subject in this article as an example,the theoretical analysis of the settlement of the viaduct pile foundation was carried out,and the settlement value of the adjacent subway shield tunnel caused by the settlement of the viaduct pile foundation was calculated.Then,the selection of the constitutive model and calculation parameters in the numerical simulation are summarized.The numerical simulation method was used to simulate the construction of the pile foundation of the viaduct,and the effect of the pile foundation rotary excavation process on the horizontal deformation and vertical settlement of the subway shield tunnel was studied and analyzed.This research analyzed and compared the effect of different distances between the tunnel and pole,pile length,and construction sequence.It was found that decreasing the tunnel absolute distance,increasing the pile length,and taking multiple disturbances of the row construction could enlarge the influence on the tunnel,which wasgenerally following the on-site monitoring results.The simulation was carried out on the pile foundation,the cap of the viaduct and the operation stage of the viaduct to study and analyze the influence on the horizontal deformation,vertical settlement,and segment deformation of the subway shield tunnel during the operation stage of the viaduct.The results of the construction phase and the operation phase were cumulatively collected and disposal,which can conclude the cumulative horizontal deformation value and vertical settlement value of the subway shield tunnel caused by the entire life of the viaduct pile foundation was obtained.At all stages of the entire life span of the viaduct pile foundation,the foundation settlement caused by the load of the upper bridge during the construction of the main structure of the viaduct was the main factor of the deformation of the subway tunnel,which had the greatest impact on the subway shield tunnel.Finally,a research was carried out on the isolation protection measures of the viaduct pile foundation of the subway shield tunnel.The protective effect of the high-pressure rotary-spray isolation pile at each stage of the viaduct pile foundation life was analyzed through numerical calculation.The protection effect of high-pressure rotary spray isolation pile of different pile diameters and different pile tunnel distances were examined,respectively.