Research On The Surrounding Rock Stress Based On Viscoelastic Theory

In China two-thirds of the land area is mountainous and hilly. With the rapid economic development, rail and road tunnels entered a rapid development period.The study of stress, displacement variation in viscoelastic surrounding rock conditions excavation and the relationship between the "surrounding rock-initial lining secondary lining" and the passed and distribution law of surrounding rock load in the surrounding rock and supporting structureand is an important topic in the theory of tunneling. During tunnel excavation stability prediction relies on the monitoring data, to optimize the monitoring program based on the inversion of purpose, the establishment of the inversion theory of multiple information sources, can provided the more close to the actual inversion results for tunnel stability analysis.In this paper, reguarded the stress and and deformation of surrounding rock and supporting structural law in tunnel excavation as research objective, based on the analysisof different excavation surrounding rock stress and deformation of the supporting structure, optimize the the tunnel monitoring program by sensitivity analysis, inversed the tunnel model and parameters, and founded the strain inversion method.The theoretical research of the viscoelastic surrounding rock excavation in the moving boundary conditions. Considering the surrounding rock stress and deformation law of the tunnel under time-varying conditions after excavation, to study the relationship of the the displacement incremental release rate and the release of stress increment rate in this condition, as well as the distribution of load between the initial lining system and the second lining after the construction of the second lining.Based on the on-site strain monitoring, using sensitivity analysis to study the optimized theory of the monitoring scheme which amid at the back analysis of the strain, to build the back analysis methodology of the strain.Researching, in the viscoelastic conditions, the influence of reinforcement measures in the tunnel construction on the tunnel surrounding rock and supporting structure. Studying the influence of feet-lock bolt on the tunnel arch’s settlement, and tunnel surrounding’s convergence, as well as the influence of the time and excavation steps on the supporting effect. Studying the function of the form of temporary invert in the the different excavation manner, the stress and deformation of temporary invert, surrounding rock and initial support varying with time.Doing numerical simulation and analysis of three-dimensional tunnel, to research the relationship of excavation surface, monitoring section’s displacement, stress and strain during tunnel excavation, to analyse the different excavation surface’s distance, the displacement and stress release rate’s changes of the different positions on the monitoring section, to study different rock’s influence on the displacement release and the displacement release of the bidirectional excavation tunnel during transfixion.Main innovations:(1) Derived analytical solution of a circular viscoelastic tunnel surrounding rock and supporting structure the displacement in conditions do not ignored the the displacement in tunnel borderline, and defines the the displacement incremental release rate and the stress increment release rate, analyze the relationship between the two release rate,,proposed the time of the secondary lining can be determined based on the release of stress increment.(2) propose the surrounding rock internal strain monitoring method by using of steel wire sensor, initially established the strain back-analysis system based on strain information theory, Determined the experimental evaluation of strain back analysi and the objective function of optimization of back-analysis.(3) Researched supporting effect and the relationship between the construction time of feet lock bolt and temporary invert in viscoelastic suround rock.