The Influence Of Structural Joints Of Bias Tunnel

Our country mountain horizon,terrain steep it,complex geological conditions,in the construction of traffic tunnel,takes up a large portion of bias tunnel.When the shallow buried tunnel built along the mountain or along the river,due to the asymmetry of tunnel left and right side of the terrain,surrounding rock stress distribution around,form the bias of the tunnel section.Bias effect makes the stress of tunnel lining structure at a disadvantage,and may result in the crack of the primary support and secondary lining,greatly reduce the bearing capacity of the tunnel structure.In addition,when the tunnel through the mountains,because the rock mass within the natural joints and fissures,make the effect of the stress of the tunnel appears larger,which often form of supporting structure and the construction of the tunnel is put forward higher requirements.Joint is a common geological phenomenon,the existence of the joint,greatly reduce the strength of the rock.In the slope,there is a lot and the occurrence of the joint group of deforming toward the surface,will exacerbate the formation of the landslide,collapse,poses a serious threat to the safety of the buildings.In general,the tunnel inevitably through the joints and adverse geological conditions such as weak intercalated layers.Therefore,discuss the influences of joint of tunnel excavation and lining has more practical meaning is an important subject.This study in henan tunnel of an expressway as the research object,by the numerical simulation analysis and field problems and processing measures in combination with the measured data from the surrounding rock properties,buried depth and terrain bias Angle research and structure internal force and deformation of tunnel surrounding rock pressure,for bias tunnel design and construction of soft ground to provide theoretical basis.By conducting bias the forced deformation of the tunnel and its control technology research,to ensure the safety of unsymmetrically in weak rock tunnel construction,the reasonable support has important guiding significance,and can be further applied to other biased in weak rock tunnel construction in China,the application prospect is very broad,economic and engineering benefit is remarkable.Starting from the basic theory of tunnel mechanics,on the basis of the measured pressure value of surrounding rock,the load-structure model is established,the tunnel at the beginning of the internal force analysis,calculation of load on the tunnel structure size.When the paper established calculation model,selecting typical sections,determine its terrain section,determine the size range of analysis model,the calculation model is divided into several areas: outside tunnel surrounding rock area,a lining,the secondary lining and staged excavation area,finite element meshing,and considering the construction process of anchor rod is divided into stem cells,using unit technology to simulate the excavation process of life.Paper USES the combination of theoretical analysis and finite element numerical simulation method,from the joint Angle,groundwater and other factors on the influence of the bias effect has made the following research:(1)Through theoretical analysis,it is concluded that under normal circumstances,the shear strength of rock mass along the direction has the lowest level,and has the highest in the vertical direction of level;(2)Through the theoretical analysis and calculation,in vertical direction and horizontal direction of the bedding rock stress has the following relationship:(?),at the same time,the effect is obtained in the size of the load on the tunnel structure;(3)The large finite element software of ABAQUS,simulation the influence of different Angle of the structural joints of bias tunnel,analysis the tunnel surrounding rock stress change laws of internal force distribution and the lining;(4)On joint bias tunnel,on the basis of theoretical analysis and numerical research,recommending bias tunnel surrounding rock supporting structure design,provide reference for engineering.