Study On Construction Interaction Of Shallow Buried Bias Tunnels With Small Span

Currently with the deep development of ?The Belt and Road Initiative? strategy,the focus of Chinese traffic construction gradually extended to the midwest area.Therefore,the tunnels that pass through mountainous and hilly areas are gradually increased.To satisfy the requirements of terrain conditions and the overall line shape,the tunnels are usually constructed with small clear spacing tunnels with flexible spacing.Therefore,it is necessary to systematically study the mutual interaction between adjacent tunnels in small spacing under such condition.According to the existing research results,this thesis use the finite element software ANSYS to simulate and analyze the construction process of the shallow buried bias tunnels with small span.This article mainly studies the change and regularity of the mutual influence between the first and next grotto under different construction spacing and different excavation methods.The main contents and conclusions of this thesis are as follows:1)According to the exiting research results,this thesis summarizes the judgment condition,construction technology characteristics and the theoretical calculation method of construction interaction of the shallow buried bias tunnels of small span.2)This thesis establish two dimensional numerical model,according to the single side drift method and bench-CRD method.The variation laws of stress and displacement of surrounding rock under different two excavation methods are compared and analyzed.The stress concentration of surrounding rock usually appear on the arch foot under two kinds of excavation methods.The stress of the first grotto increases in order from top to bottom,and the displacement change is the opposite.The stress and displacement of the middle and upper rock wall are greatly affected by the tunnel construction.Through comparison and analysis of the results of two excavation methods,the single side drift method is better than the bench-CRD method.3)Through the three-dimensional numerical simulation study we found that the ultimate value impacted on the spacing of the tunnel construction of the indicators is tiny,but different construction on the surrounding space,especially in the construction of folders in each cycle of rock is influenced obviously.The surrounding rock in the area of 1B(B for tunnel excavation diameter)is greatly influenced by construction.Through the comprehensive analysis of the results of calculation and the requirements of different construction space,it is determined that the rational construction spacing is 1.5B ~ 2.B for this project.