Analysis On The Stability Of The Side Slope Of Typical Entrance Of Bao-Lan Line

That the line of the Borland passenger dedicated Tianshui to Lanzhou section walk in the Tianli basin and gully hill area of the Longxi loess plateau.Due to the terrain of loess ridge and hill is gully aspect and high, low and so on. Also, there are plenty of slopes which are high and steep. Therefore, the line through the region mainly by bridges and tunnels.That near the tunnel's caves with adverse geological body more developed owing to that cave of the tunnels at the new lager of loess which is loose structure and low intensity. So, that stability of slopes where tunnel's caves in is key to the whole high-railway construction of Tianshui to Lanzhou section.This paper takes that slopes where tunnel's at which in the Tianshui to Lanzhou section as target. The paper analyzes stability of the slopes. The main research's results achieved as follows:(1) The article summarizes and analyzes that the failure factors of the tunnel portal slope in the Longxi loess plateau, also including failure cause and model of slope deformation. In this paper, we derive the expression of the safety factor and its variation in the case of the excavation of the tunnel.(2) Selection of representative tunnel portal slope in the section of passenger dedicated line. Using Li-zheng geotechnical calculation, geo-slope and Midas-GTS software evaluates the stability by limit equilibrium method and strong reduction.(3) The finite element numerical simulation method is used to simulate the deformation of the slope under different excavation methods and different buried depth. Through the analysis found that:due to different excavation methods and excavation of the site, a supporting structure different, resulting in the slope should force, displacement release is not same, eventually leading to affect the stability of slope is not the same; through the comparison of different depth of the slope change. It is found that with increase in depth, more conducive to the bias tunnel slope stability.(4) Selecting the typical tunnel portal parallel to the slope, through the dynamic simulation of the excavation of the hole and the hole of the construction, research and analysis of the deformation of the slope.