Stability Analysis And Evaluation Of High Pressure Hydraulic Tunnel Lining Structure

The stability of lining structure of hydraulic tunnel in excavation and operation period under the combined action of high stress and high internal and external water pressure is an important rock and soil mechanics problem.In this paper,the typical deep buried high-pressure hydraulic tunnel is taken as the research object and background.Surrounding rock is the main bearing structure and anti-seepage main body.Adhering to the design concept that surrounding rock is the main bearing structure and anti-seepage main body,and shotcrete and anchor support,secondary lining and surrounding rock grouting ring constitute a composite bearing structure,the stability of the lining structure of hydraulic tunnel under high water pressure is demonstrated,to provide certain reference for the same type of structural design.The main research results are as follows:?The damage zone evolution and long-term strength of deep hard rock in deep hydraulic tunnel have significant time effect.Its long-term deformation and failure are the comprehensive result of construction,high in-situ stress,topographic and geological environment(groundwater,underground water,temperature and physicochemical effects),rock mass structure and supporting time.? Through the rheological experiment of hard rock in deep buried hydraulic tunnel,the key mechanical characteristics and laws of long-term deformation and failure of typical hard rock can be obtained: The increase of stress level will make the hard rock show certain volume expansion phenomenon during long time loading and the internal damage of hard rock evolves continuously with time.During the long term loading,the hard rock changes from viscoelastic deformation to viscoplastic deformation,leading to the rheological strain increases and the rheological damage evolution.The results of CT scanning show that the long term damage of hard rock begins to accumulate in the middle part,and then develops to the two ends of the specimen,which will eventually lead to a large expansion deformation.? The mechanism of lining water pressure is mainly reflected in: High stress fractured rock mass,and high water pressure fracturing fissure rock mass,providingpossibility for groundwater flow.The outer edge of lining and grouting ring will produce high external water pressure.The effect of water pressure on lining is dualistic.The dynamic change of effective stress field leads to the further response of rock mass rupture,and the change of internal and external environment causes the change of tunnel lining force.? The stability analysis method and calculation flow of lining structure of deep buried high pressure hydraulic tunnel are put forward.The advantages of this method are: The excavation,initial support and lining of deep buried high pressure hydraulic tunnel during the self-construction period and the whole process of consolidation grouting and water filling operation are fully considered.The long-term damage of surrounding rock and the influence of external water pressure and internal water pressure are taken into account.The simulation calculation is based on the water storage period,operation period and overhaul period to evaluate the stability of hydraulic tunnel lining.,by the evaluation indexes of plastic zone,the maximum and minimum principal stress and the plastic zone.? The stability analysis method of hydraulic tunnel lining structure is used to calculate and analyze the stability of lining structure under different working conditions and types of lining structure,and the evaluation results of lining stability of different combination tunnels are obtained.