Construction optimization of PBA of Subway station tunnel excavation and its cross section in loess area

This paper takes the project of Hejiaying Station Xi'an Subway Line 2 as background for study. The dynamic numerical simulation construction process station by PBA method is carried out using 3D finite element method. changes surface settlement, vault headroom convergence and structural stresses are studied up to intersection guide tunnel large section duct. research results show that: upper hole has a small effect on deformation internal force initial support structure lower pilot will increase duct, especially holes 3 lead significant in Therefore, it necessary make 10m reservation main line, grout cross ensure safe section.