The Temporal And Spatial Effect In Construction And Control Of Large Deformation Of Tunnels In Squeezing Ground

Coupling with high crustal stress and large deformation, deformation of soft rock tunnel always correlate with time. Based on theological mechanics of geomaterials, the mechanism of interaction of surround rock and support structure can be explained, and mechanical analysis can be applied to information design and construction of tunnel. By analytical theory, numerical simulation, and on-site full-scale experimental research with example of Wu Shaoling Tunnel Project, the stability and dynamic control of tunnel in squeezing ground were researched in this dissertation.Based on the analysis of typical tunnel engineering example in squeezing ground, the mechanical characteristic of squeezing deformation were concluded. The squeezing deformation was defined based on view of theological mechanics, and squeezing deformation can be regarded as theologic deformation along with fast rate of deformation and slow convergence. Furthermore, the mechanical mechanisms of squeezing deformation were studied. Also, the control method for squeezing deformation was proposed, involved both prediction of squeezing potential in design phase and grade judgment of deformation in construction phase.Mechanical behaviors of tunnel excavation in squeezing ground are dynamic process of space and time. The temporal and spatial nonlinear coupling action with the excavation process of tunnel in squeezing ground was analyzed in this dissertation. Considering spatial effect of excavation face and time-dependent characteristic of soft rocks, the interaction between supporting structure and surrounding rocks with time is deduced through analytic method. The research expanded the existing analytic solution and was helpful for further understanding the interaction of squeezing surrounding rocks and supporting structure.Rational mechanics parameter of squeezing rocks is very important for understanding the mechanical characteristic of rocks and improving the reliability of numerical simulation. Based on the displacement time series from field monitoring, rheological parameter of rocks were obtained by numerical inverse analysis. Furthermore, visco-elastic constitutive model of squeezing rocks were identified. The research provided rational constitutive model and rheological parameter for stability analysis of tunnel in squeezing ground.Four-dimensional temporal and spatial geometry can well and truly describe squeezing phenomena. In this dissertation, three-dimensional numerical model with visco-elastic-plastic constitutive and large deformation was established, and the construction time-varying mechanics was simulated. During excavation period of tunnel in squeezing ground, temporal and spatial nonlinear evolvement process were investigated. The research enriched the theory of construction mechanics of tunnel engineering.The critical problem of design and construction of tunnel in squeezing ground is the betimes and validity of stability control of surrounding rocks. In this dissertation, rheological mechanics theory of rock was used to optimize lining time, inverted arch time, and bench length and bolt parameter. Based on the on-site full-scale experimental and optimization analysis, design and construction of tunnel in squeezing ground were researched by theory of dynamic feedback and control, and the control principle for squeezing earth pressure was established.