Key Technology Research Of PBA Construction Of Metro Station

Based on the Beijing subway line on the6th of Chaoyang Gate Station construction of PBA method, The one hand, studied the PBA method due to construction of surface settlement law, On the other hand combined with the field settlement monitoring data to create three-dimensional finite element numerical calculation model. Computational simulation of the whole process of the construction of the PBA method. Sedimentation analysis showed that:Chaoyangmen station construction PBA method maximum surface settlement of not less than60mm measured points reach91.3%of the total, and between80mm and85mm measured points reach43.48%of the total. The surface settlement of measured points are all under85mm. The surface settlements caused by three typical construction stages which are pilot tunnel excavation, side pile and center post construction and upper arch works are more than90%of the total, and the surface settlements scale is roughly4.5:1:3. The ground loss ratio caused by Chaoyangmen station construction in PBA method is between0.69%and0.96%. The width parameter of Chaoyangmen station surface settlement tank is0.78.Numerical simulation results of the PBA method construction show that the principle of pilot tunnel excavation is that the construction sequence is from up to down and left to right.The surface settlements caused by the pilot tunnel excavation in the best that the construction sequence is the upside, the upper and middle part, the bottom, the middle and lower part decreases12%, than the worst one that the construction sequence is the bottom, the upper and middle part, the middle and lower part,upside. The surface settlements caused by upper arch work in the solution that side arch is excavated firstly are decreases5.5%, than in the other solution that hogging is excavated firstly. So the principle in sequence of upper arch work should be followed, that side arch is excavated firstly and hogging is excavated then.