Three-dimensional Stability Analysis Of Tunnel Through Ancient Landslides In Conditions Of Complex Unfavorable Geology

In recent years,with the continuous progress of the construction of"belt and road"in China,high-speed railways and expressways have ushered in new opportunities and challenges.Yinxi High-speed Railway is an important part of the Railway Network of the National Medium and Long-term Railway Network Planning.Adverse geological conditions are the constraints of road construction,which not only affects the difficulty of engineering construction,but also affects the success or failure of the project.Therefore,the study of the numerical simulation of high-speed railway crossing adverse geological conditions is of more significance.This paper takes a section of ancient landslide project through the Yinxi high-speed railway as the background.Through collecting soil samples on the tunnel face,UAV topographic map scanning,Lab test and numerical simulation analysis of the prototype site,the numerical calculation and analysis of the three-dimensional stability of the tunnel through the ancient landslide was carried out.The author collects the topographic and geomorphological data of ancient landslide by using tilted UAV photography technology,a three-dimensional geologic model was established,the structural Mohr-Coulomb constitutive model was embedded into FLAC^3Dfinite difference software,The stability of the Yinxi high-speed railway crossing the ancient landslide is calculated,and the deformation,the structural and the plastic zone change of the slope are analyzed.According to the calculation results,the deformation of the engineering slope mainly occurs at the steeper position of the slope.Compared with the calculation under the plane strain condition,the three-dimensional slope stability calculation can reflect the actual three-dimensional variation of the slope.The actual working conditions of existing anti-slide piles are analyzed,and the strength of anti-slide piles under the combined action of shear force and bending moment is checked.According to the calculation results,it can be known that the anti-slide pile reinforcement meets the requirements.The tunnel and the backfilled open tunnel through the slope is calculated.For the bored tunnel,the settlement of the arch,the settlement of the ground and the stress of the lining are analyzed.It is pointed out that under the action of surrounding rock pressure;the most unfavorable position of the lining is the bearing and the deformation of the left side of the tunnel.For the backfilled tunnel,the settlement deformation of the landfill and the stress state under the overlying load are analyzed.Finally,the paper studies the influence of the excavation construction disturbance of high-speed railway tunnel on the stability of ancient landslide,which indicates that the construction disturbance of tunnel excavation has little effect on the sliding of ancient landslide.