Study On The Stability Of Mountain Tunnel Portal In Layered Phyllite Slope And Its Control Technology

The anti slide pile with prestressed anchor cable is the most effective measure to reinforce the slope sliding failure,However,because of its complex contact with rock mass;Uncertainty of structural mechanics calculation model;The study on the reinforcement effect of different landslide failure forms and strata rock conditions is not perfect;Therefore,on the basis of the current research situation of prestressed anchor cable anti slide pile,Combined with a large number of domestic and foreign scholars research results,Using numerical simulation and in-situ monitoring research methods,layered phyllite formation conditions of mountain tunnel slope stability and its control measures were analyzed,The main work is as follows:1.Based on the field investigation of the tunnel portal slope with cheng-lan line,The physical and mechanical characteristics of the layered rock slope,such as topography,stratum lithology,joint occurrence,and so on are understood,And access to a large number of relevant literature,In this paper,the research status of the anti slide pile with prestressed anchor cable and the current calculation theory are summarized,and the practical problems to be solved are put forward.2.Aiming at the stability problem of layered phyllite stratum conditions exist under the cheng-lan line of the tunnel portal slope,The failure modes of layered rock slope are simulated by the Joint constitutive model in FLAC3D numerical simulation software.Analysis of the rock physical mechanical parameters under layered phyllite with single factor influence of tunnel slope sliding failure,The failure mechanism of the rock mass is summarized.3.Simulation of layered rock slope using FLAC3D 3D modeling,The contact between pile and rock mass is established.The effect of no anti slide piles and prestressed anchor anti slide piles on the stability of layered rock slope is analyzed.The distribution of the contact stress and the internal force of the pile body after the application of the prestressed anchor cable is analyzed,In this paper,the relationship between the fixed point and the maximum bending moment of the sliding surface of the pile is analyzed by means of the Mohr-colomb model and the joint constitutive mode,The differences between the two are expounded,To provide the necessary basis for the control of slope stability under layered phyllite stratum.4.This paper analyzes the influence of the application of prestressed anchor cable anti slide pile on the displacement variation of the tunnel portal slope,And failure mechanism and model of tunnel entrance slope,Furthermore,the influence of tunnel excavation on the stability of the slope of the tunnel entrance is obtained.5.Through numerical analysis,The anti slide pile with prestressed anchor cable as the main control technology of tunnel slope stability of layered phyllite.On the spot monitoring of prestressed anchor cable anti slide pile in a typical tunnel portal slope under cheng-lan line,Comparative analysis of pile internal force,stress and top displacement variation under layered phyllite stratum.