Stability Analysis Of Diversion Tunnel Lining Under High Temperature And Geostress

With the implementation of West development strategy of China,tunnel and others underground engineering on traffic construction and hydroelectric resources development etc.gradually develop to the deep and long direction.The construction of tunnel underground always faces special problems of engineering geology because of high ground stress and high geothermal,that greatly affects the process of tunnel building and operation.The study take the headrace tunnel section with high ground temperature in the Qirehataer Hydropower station as engineering background.On the basis of determining the material parameters through physical experiments,the numerical experiments of the lining under the condition of high temperature and high ground stress are carried out by using the finite element software ANSYS.The stability of tunnel surrounding rock an lining was analyzed under ventilation period and water phase.According to the geological condition on the construction site,the author reasonably select the factor,which has the greater influence on the stability of surrounding rock and safety of lining of high geothermal.The regular pattern of several key factors to the force of supporting structure were studied,the theoretical and data support were provided for the design,construction and operation of diversion tunnel of high geothermal.Thus the conclusion was formed below:(1)The maximum tensile stress of the lining of headrace tunnel was present to the flank position.The maximal compressed stress at the arch basal foot for the city-opening shaped and the stress concentration was formed.The stress mutation was occurred at the junction of lining and surrounding rock,but the amplitude is not large.So,the sidewall and the arch foot were the important and key areas for the stability of lining.(2)Through an analysis of the effects of several key factors on the high temperature tunnel lining stress show that the maximum tensile stress of the lining is decreased with the increase of the lining thickness.Lining stress is affected by the initial temperature and the elastic modulus of surrounding rock.Improve water temperature can not effectively reduce the temperature difference between inside and outside of the supporting structure.The increase of water temperature could decrease inner temperature drop of lining and decrease inner stress of lining;the temperature difference between the inner supporting structure and the outer was not decreased efficiently by increasing water temperature,and the stress difference of lining was not changed greatly.