Numerical analysis and research on adaptability of excavation methods for biased strata tunnels in mountainous areas
In mountainous areas,there are often situations of biased pressure or rock fragmentation.When tunnels pass through this stratum during construction,it is difficult to control the deformation of the surrounding rock,and construction disturbances can easily lead to the collapse of the tunnel arch and damage to the supporting structure.This article relies on the Silver Flower Tunnel project to conduct adaptive numerical simulation research on the excavation method of biased stra-ta tunnel construction.It compares and analyzes the influence of different excavation steps on the deformation of weak sur-rounding rock,arch crown settlement,and maximum principal stress distribution in the"three guide tunnel method"and"middle guide tunnel method".The results show that with the excavation of the side guide tunnel at the biased position,the settlement zone of the left tunnel arch and the disturbance deformation zone of the middle guide tunnel will form a set-tlement superposition.The maximum construction site settlement occurs after the excavation of the main tunnel,which is-12.35 mm,accounting for 55.23%of the settlement ratio η.During the construction of the central guide tunnel,the maximum settlement value is distributed in a fan-shaped manner at the biased arch waist.The settlement ratio generated by the construction of the upper steps on the left and right tunnels reaches a maximum of 73.57%.The excavation of the middle and lower steps has little impact on the settlement of the arch crown,with a maximum settlement value of-17.81 mm.The maximum principal stress of the two methods is not strictly symmetrical.Although the construction of the middle guide tunnel method generates significant settlement,considering construction costs and efficiency,the"mid-dle guide tunnel method"is more reasonable.
biased formationmulti arch tunneldeformation of surrounding rocksettlement of arch crowndistribution of maximum principal stress
万方数据
维普
