The Influence Law Of The Existing Bridge Pile Foundation Caused By The Tunneling Construction Of Tong-hu Running Tunnel

It has significant theoretical meaning and engineering reference to study the influence law ofthe existing bridge pile foundation caused by the shallow-covered excavation of metro tunnel inXi’an loess area. This paper based on project of shallow-covered excavation of the section tunnelfrom Tonghuamen to Hujiamiao railway station in Xi’an Metro Line3. The study work of thisthesis is adopting the combined method of theoretical analysis, numerical simulation and fieldconstruction monitoring, and the corresponding control technology on deformation is put forward.The main work and conclusions are followed:(1) The influence law of surface deformation affected by some factors and the characteristicsof ground deformation caused by the shallow-covered excavation are analyzed theoretically, theinfluencing factors main include formation characteristic, ground water, tunnel depth,constraction way, excavation driving, etc. The results show that the deeper the adjacent pilefoundation is, the easier the foundation inclined which caused by shallow-buried sub-surfaceexcavated tunnel construction, meanwhile, the shallow-buried sub-surface excavated tunnelconstruction induced ground deformation, and the deformation of bridge pile foundation withdifferent forms is mainly caused by means of the horizontal deformation and verticaldeformation. This paper summarizes some control measures for the deformation of surface andbridge pile foundation which commonly used in tunneling construction, and combined with theconstruction experience in Xi’an area, then puts forward deformation control standard of surfaceand bridge pile foundation that caused by the tunneling construction of Tong-Hu running tunnel.Study on the influence law of the existing bridge pile foundation caused by the tunnelingconstruction of tong-hu running tunnel by using of FLAC3D software. A comparative analysis oftwo kinds of underground excavation construction methods induced the deformation Laws of surface and Changle Bridge of East2nd Ring Road, and bench method and CRD method are twokinds of construction methods. The simulation results show that the CRD construction methodinduced the deformation of surface and Changle Bridge is very small in comparison to the benchconstruction method. But the deformation control measures still need to be put forward for thebridge in tunneling construction. The tunneling construction scheme was determined by means ofcomparing and selecting, and considering the difficult problem of precipitation construction insaturated loess, the CRD method should be adopted for tunnel construction in collapsible loessbecause of it had little influence on the deformation of bridge pile foundation.In order to control the deformation of surface and existing bridge pile foundation caused bythe CRD construction method, using the sleeve valve tube grouting technique to strengthenperipheral earth soil around the bridge pile foundation. Based on practical engineering, makingout the deformation monitoring scheme of construction site, then comparative analysis of the fieldmonitoring results and the prediction results. The results show that the deformation trend of actualmeasured ground settlement curve is do the same as the simulation predicted curve, after usingthe sleeve valve tube grouting reinforcement measures, the deformation of surface and ChangleBridge can be controlled in the allowable range, and the safe operation of bridge has be ensuredduring the mined tunnel construction period.