Study On The Effect Of Subway Station PBA Method On Ground Surface

This paper reviewed the engineering background and the domestic and oversea present situation of research, and introduced conventional construction methods of PBA , analyzed the ground settlement law caused by PBA construction and discussed surface deformation control measures. Combined youth street subway station and construct FLAC3D numerical model and analyzed the dynamic excavation process effect of PBA method on ground settlement and make a comparative analysis of numerical simulation and monitoring result in practice.PBA construction method is a new method combining traditional frame construction method with undermining method, which undermine soil and construct second staining under the care of slope stake, center stake and arch prefabricated. PBA construction method is remarkable for easy application, settlement controlled effectively and meeting complex city engineering environment, so this construction method is more popular within engineers than many other construction methods.Pilot tunnel excavation is an important working procedure, and is nonlinearity route relative to ground settlement induced by excavated that different excavation sequences and footages bring about the different effect on the surrounding environment. The paper used numerical simulation software FLAC3D, constructing mathematical mechanics model and further analyzed different excavation footage effect on ground settlement on the condition of different excavation sequences of 6 types of construction methods. Through comparing numerical simulation results, the construction plan that is minimal effect on the surrounding environment can be determined. Through comparative analysis between real data and numerical simulation results, the influence laws of ground settlement caused by different construction stage of the PBA construction method are summarized. It is important to guide similar projects design and construction for these laws.