| The Dianzhong Water Diversion Project has the characteristics of a large water diversion scale,long tunnel routes,and extremely complex geological conditions,and both the project scale and technical difficulty rank among the world’s top.Among them,the tunneling project passes through soft rocks represented by the"Dianzhong red layer",accounting for about 32.67%,which seriously affects the construction and operation safety of the project.Based on the study of the deformation of the soft rock surrounding the tunnel,the article relies on the Wuzhuang Village tunnel in the Chuxiong section of the Dianzhong Water Diversion Project,and comprehensively uses theoretical analysis,numerical simulation,monitoring,and other technical means to conduct research on the full displacement of the tunnel surrounding rock,including advanced displacement,monitoring loss displacement,and the control benchmark of surrounding rock deformation.The main research content and results are as follows:（1）By studying the mechanical model and constitutive equation of the basic elements and combined elements of rock deformation,the internal stress-strain relationship of rock is analyzed,and the deformation characteristics of tunnel surrounding rock are revealed.Based on the convergence constraint theory of tunnel surrounding rock deformation,the displacement deformation characteristic curve and the influencing factors of tunnel deformation are analyzed,and the relationship between tunnel support structure and surrounding rock deformation and stability criterion are determined,which provides theoretical support for reflecting the deformation properties of tunnel surrounding rock,the calculation of rock mass stress field and stability analysis.（2）A calculation method for the full displacement of the tunnel,including advanced displacement and monitoring loss displacement,is proposed to overcome the shortcomings of conventional monitoring measurement being unable to measure the advanced displacement caused by tunnel excavation disturbance and the displacement lost due to the failure to install monitoring equipment in time.Through regression analysis of field monitoring data and numerical simulation results,it is known that the advanced displacement is 9～18mm,the loss displacement is 5～8mm,and the full displacement of the surrounding rock deformation is 26～48mm.The ratio of the advanced displacement X0 to the full displacement X of the surrounding rock,that is,the ratio of the surrounding rock advanced displacementβ0,is calculated as 0.3～0.4,which is consistent with the actual deformation law of the surrounding rock in the engineering field and provides a theoretical basis for determining the reserved deformation amount.（3）By analyzing the full displacement curve of the surrounding rock obtained in this article,it can be known that the internal displacement of the surrounding rock changes in an"S"shape,namely,three stages of initial growth,rapid growth,and stable convergence.The range of the constraint effect of the arch space is roughly 3 times the diameter of the hole before and after.The rate of change of the tunnel surrounding rock deformation increases gradually as the excavation progresses.When it reaches the research section,the deformation rate reaches its maximum,and the advanced displacement produced at this time accounts for about 35%of the full displacement.（4）Regression analysis is used to study the on-site measurement data of 40research sections,and the best-fitting equation is obtained,and the value of the loss displacement is deduced to account for about 30%～60%of the measured displacement.Based on the measured data of surrounding rock deformation,combined with the confidence interval obtained in the normal distribution and the maximum deformation value of the monitoring section,and considering the influence of loss displacement,it is proposed that the reserved deformation amount of the class Ⅳ hard rock section in the Wuzhuang Village tunnel of the Chuxiong section of the Dianzhong Water Diversion Project is about 25～45mm,and the reserved deformation amount of the class Ⅳ soft rock section is about 30～60mm. |
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