Research On Stability Control Technology Of Surrounding Rock In Weak And Fractured Zone Under Complex Conditions

The“Belt and Road”strategic system promotes the vigorous development of highway construction in China.In recent years,China's highway development model has changed from shallow to deep buried complex,construction site from flat to mountain crossing,the engineering geology encountered from distinct to complex.During the construction of deep-buried complex tunnels,complex geological problems such as geological tectonic zones,high ground stresses,and weak fractured joint fracture zones are becoming increasingly prominent.In this paper,the seventh contract section of Taoziya tunnel,which is the controlling project of the weak broken zone of Zhengxi highway in Zunyi City,is taken as the research object.The main research methods of indoor experiment,theoretical analysis and numerical simulation are combined to rock stability control technology conducts in-depth and systematic research and forms the following main results:(1)It is determined that the whole of the seventh contract section of the tunnel is???grade surrounding rock,and the weak broken high ground stress section is?_bgrade reinforced surrounding rock;the structural state of rock and soil mass,the engineering properties of rock mass,groundwater and the shape of the tunnel are found And the size,the supporting method and time,the construction method and the depth of the tunnel have a great influence on the stability of the surrounding rock of the tunnel.(2)The MTS815 electro-hydraulic servo full-stress rock testing machine was used to carry out indoor Brazilian splitting,conventional uniaxial and triaxial loading on rock samples,and the full stress-strain curve of the surrounding rock in the weak fracture zone was obtained;through the triaxial unloading test,simulated the excavation conditions of the surrounding rock across the broken mileage section under different initial confining pressures,different unloading rates and paths,and comparatively analyzed the unloading mechanical characteristics and differences of the two crossing sections under different initial confining pressures and explored The influence of unloading path and unloading rate on unloading deformation of tunnel surrounding rock is discussed.(3)The FLAC3D analysis software was used to carry out numerical simulation analysis on the stability of the surrounding rock in the weak and broken zone of the Taoziya tunnel,and the main form of the unstable failure of the Taoziya surrounding rock was determined;The horizontal and horizontal displacements,the maximum and minimum principal stresses and the distribution law of the plastic zone verify the correctness of the on-site monitoring conclusions.(4)Mastered the deformation law that the horizontal convergence value of the tunnel is greater than the settlement value of the vault;developed a settlement control benchmark table for the surrounding rock construction settlement in the weak and broken zone of Taoziya tunnel,combined with the control benchmark table and large deformation judgment level,and determined the tunnel mileage ZK58 Section+550?ZK58+580 is the second-level displacement severe settlement and convergent large deformation section,and the other mileage sections are judged to be the first-level grade small settlement and convergent large deformation section.Suggestion table for the surrounding rock support parameters of the weak and broken section of the Taoziya tunnel.This paper takes the stability control technology of the surrounding rock of the Taoziya tunnel in the seventh contract section of Zhengxi Highway as the starting point to carry out research,combining theory with practice,and its research ideas,technical routes and research results can provide some reference for similar projects reference.