Research On The Key Techniques Of Multi-Arch Loess Tunnel In Steps Excavation Method

Because of the step-method’s construction process is relatively simple and alsoreduced the amount of temporary support relative to both side heading method. So ifstep construction method is adopted after loess multi-arch tunnel middle drift is formed,not only can save the investment by a large number of temporary support, but also canspeed up the progress. Therefore develop the research of steps excavation method’sadaptive and key technologies after formation middle drift, has realistic meaning andpractical value.This paper relays on the QingLiangSi multi-arch loess tunnel in Shanxi provence,with the method of numerical simulation to research two construction methods:bothside heading method and bench reservation core soil of this loess tunnel.Analysis themechanical behavior of the two different construction methods,combined with themulti-arch loess tunnel’s actual situation, to determine construction method of theQingLiangSi multi-arch loess tunnel. While loess tunnel that adopting steps excavationmethod using the finite element strength reduction method to study every step’s safetyfactor,We can know that the eighth step-excavation of the right hole ring soil and theforteenth step--excavation of the left hole ring soil are the most dangerous excavationsteps because of their safety factors are1.02and1.00. Because of the complexity of thetunnel structural, the stability of tunnel excavation process and the safety of thesupporting structure of different intervals on stage are researched when tunnel thatadopting steps excavation method.Based on the study of QingLiangSi multi-arch loess tunnel, to promote the researchon Multi-arch loess tunnel which using Steps excavation method. Through numericalsimulation, get the multi-arch loess tunnel construction’s key technologies underdifferent surrounding rocks and span, core wall thickness, buried condition:①middlewall,②temporary support,③DaoKeng arc, excavation distance between core soil andunder steps,④changes of surrounding rock,⑤buried depths,⑥the excavation of thering core.