浅埋偏压连拱隧道的开挖顺序和衬砌结构型式是隧道工程成败的关键环节之一，本文按地层—结构法原理建立有限元数值模型，对偏压双连拱隧道开挖顺序和结构型式进行数值分析、对比，找出最佳施工方案，并使其设计更趋合理。 本文结合偏压连拱隧道工程实际，将内侧或外侧先开挖两种方案各划分为十四个工序（含一个初始应力场），对每个工序进行对比分析，得出浅埋偏压连拱隧道采用外侧先开挖产生的围岩拉应力区和塑性区、初衬位移、中墙相对位移以及二衬拉、剪应力集中区分布等均较内侧先开挖优的结论。并指出连拱隧道施工应重点控制围岩及衬砌位移量，特别应避免中墙向外侧倾倒，防止衬砌开裂。研究表明，偏压连拱隧道采用外侧先开挖有利于衬砌及围岩稳定。 论文选择三种适应性较好的连拱隧道衬砌型式（整体直墙连拱、整体曲墙连拱和分层曲墙连拱）按外侧先开挖分为十四（六）个工序进行施工过程数值模拟对比、分析。研究表明，曲墙衬砌要优于直墙衬砌，整体曲墙衬砌较分层曲墙衬砌结构受力稍大，拉、剪应力集中稍明显，但衬砌位移（收敛）、围岩塑性区量略小。因此在偏压连拱隧道中应优先选用曲墙衬砌，当围岩条件较差时，维护岩体的稳定性要放在首位，应采用整体曲墙衬砌；围岩稳定性较好时，隧道设计应优先考虑采用有利于结构受力的衬砌型式，可采用分层曲墙衬砌。 本文采用数值分析方法所得出的结论基本反映了浅埋偏压连拱隧道结构实际状态，可在类似大型复杂地下结构数值模拟中推广应用。

Excavation sequence and structure cross-section patterns of Shallow, twin-arch tunnels are one of the key links of engineering success of shallow,unsymmetrical pressure, twin-arch tunnels,This paper builds up FEM simulation model based on the geologic strata- structure method principle.Analyses & contrasts several common construction sequence and structure cross-section patterns of twin-arch, highway tunnel to finds out the best project,The project is more scientific & reasonable to the design of shallow,unsymmetrical pressure, twin-arch tunnels. This paper divides the two construction methods into 14 steps(contain a initial stress field), Contrasts stress fields, displacement fields and plastic areas of every procedure in two construction methods.,The results of this analysis show firstly constructing the shallow-covering side of shallow,unsymmetrical pressure, twin-arch tunnels is advantageous to the stability of the lining and the arrounding rock. It is very important to control displacement of arrounding rock and lining,especially prevent the mid-board from tilting and keep the lining from cracking during constructing twin-arch tunnels. The paper choose three kinds of adaptable twin-arch lining patterns (①Straight board ,twin-arch lining ②Integrate bened board ,twin-arch lining ③Multiple bened board ,twin-arch lining) to build up FEM simulation models of shallow,unsymmetrical pressure, twin-arch tunnels, Contructing procedures of Every tunnel are divided into 14(16) steps based on firstly excavating the shallow-covering side.Those results of stress fields, displacement fields and plastic areas got from simulating analysis show that the bened board ,twin-arch lining is better than the straight board ,twin-arch lining. While, comparing two bened board ,twin-arch linings,we can find that stress concentration of the integrate bened board ,twin-arch lining is slightly serious than multiple bened board ,twin-arch lining and axis power is also slightly better.But the displacementof the lining and the plastic area of the arrounding rock are slightly smaller.From above analysis,in shallow,unsymmetrical pressure, twin-arch tunnels, The bened board ,twin-arch lining ought be adopted firstly,when the condition of arrounding rock is worse,Keeping arrounding rock stable must be put to the first,So integrate bened board ,twin-arch lining is suitable to this condition; when the condition of arrounding rock is better,the adopted lining ought be advantageous to bearing characteristic and stability,So the multiple bened board ,twin-arch lining can be used. The simulation results can reflect the real condition of shallow,unsymmetrical pressure, twin-arch tunnels and can be put into similar complicated underground engineering.