Study On The Sedimentation Of Surrounding Buildings Caused By Pit Excavation And Precipitation In Dalang Station Of Intercity Guanhui

The rapid development of China’s economy and accelerating urbanization process led tothe development of underground railway construction. However, most deep railway foundationpits are next to the intense buildings, so studying foundation pit-excavation’s impact on thesurrounding buildings has profound significance. This article studies systematically withcombining field measurement and numerical analysis and dividing analysis process intoexcavating to the bottom elevation and bottom precipitation construction based on the domesticand foreign study and DaLang station foundation pit, and reaching the following results:(1)Surrounding buildings’ sedimentation increased with the closer side larger through fieldmeasurement during excavation to the bottom elevation. Variation can be divided into twostages: tiny uniform settlement before erecting the first inside concrete support and acceleratingsettlement later. Finally, buildings tilts are5.1×10-4and4.5×10-4, fulfilling the specificationrequirements. Water level outside the foundation pit drops obviously because the depth ofinsertion of underground continuous wall was not able to completely cut off the water layer.(2)The sedimentation during the bottom construction accounted35percent of the totalsedimentation and the sedimentation controlled when the completion of the reinforced concretefloor; Recharging outside the foundation pit controlled the water level well, but thesedimentation controlling was not obvious due to the long construction period.(3) Numerical results showed that the model considering seepage fits actual situation betterby contrasting the date of considering seepage, no considering seepage and field measurement,which verified feasibility of coupling model and cleared that studying foundation pitengineering must consider the impact of groundwater.(4)Numerical results reflected well how foundation pit precipitation influences thesedimentation of surrounding buildings: during excavation to the bottom elevation, Maximumsettlement of no considering seepage model is just about55percent of considering seepagemodel and the building tilts are in huge difference; equally, during the bottom constructionmaximum settlement of no considering seepage model is just about20percent of consideringseepage model, which has a larger disparity.(5)Numerical results reflected that during the whole construction process, thesedimentation of surrounding buildings can be divided into three phases: slight deformationphrase before the second step of excavation, sharp deformation phrase before the constructionof artificial uplift pile and the last slow deformation phrase during the construction of the reinforced concrete floor. Besides, the maximum sedimentation of surrounding buildings duringthe bottom construction made up36percent of the sedimentation of the whole process, whichshould be given enough attention.（6）Change the construction consequence in the bottom construction: first pour a part offloor then begin artificial uplift pile construction and pour the floor in the artificial uplift pileposition finally. The numerical results show the maximum sedimentation of surroundingbuildings is reduced by42percent and45percent and the building tilts are accordingly smaller,so similar methods can be considered in the actual construction.