Unloading Mechanics Response Of Surrounding Rock In Squeezing Round Tunnel And Prediction

Squeezing deformation and failure of Tunnel is a kind of common disasters in underground engineering construction, adopting reasonable theory and method to analyze the law of mechanical response in squeezing tunnel and prediction of deformation in surrounding rock have great significance and engineering application value.The analytical solution research of Tunnel in conditions of uniform stress field has made good progress, but the mechanics response and analytical solution research of tunnel surrounding rock in axisymmetric stress field are not mature, and there's not recognized results yet. In view of this, by analyzing the problems existing in the analytic solution of tunnel in axisymmetric stress field, the paper taking squeeze tunnel as the object, introduces a new form of the radial stress distribution, then derives a new elastic-plastic analytical solutions of the round tunnel in non-uniform stress field.it also take the supporting of tunnel into consider. Based on this new analytical solutions,it also derives the analytical solutions of the round tunnel in non-uniform stress field with the consideration of brittle-delay switch, aging mechanical response of tunnel surrounding rock.it laids a firm theoretical foundation for analysis and prediction work of unloading mechanics effect of tunnel in non-uniform stress field.In this paper, research work is as follows:(1) this paper discusses the problem of the decomposition of the radial stress on elastic-plastic interface when derive the analytical solutions of the tunnel in non-uniform stress field.By introducing a new form of decomposition of the radial stress is elastic-plastic interface,it decomposed the radial stress into two parts.one part has nothing to do with angle and the other is relate with angle.Then it derives a new elastic-plastic analytical solutions of the round tunnel in non-uniform stress field with the supporting of tunnel consideration, and it gives the scope of application of lateral pressure coefficient lambda. At last this paper analyses the influence of initial ground stress, lateral pressure coefficient, supporting form and the supporting force on tunnel surrounding rock plastic zone depth and hole displacement.(2) Based on this new analytical solutions,it also derives the analytical solutions of the round tunnel in non-uniform stress field combined with the consideration of brittle-delay switch formula which considering the effect of confining pressure. Then it analysis and prediction law of unloading mechanics response of the tunnel surrounding rock with with the consideration of brittle-delay switch model.(3) with the introduction of considering the effect of excavation space constraints Vlachopoulos calculation formula, the paper analysis and forecast the rule of the evolution of the deformation of tunnel surrounding rock along the tunnel axis.(4) with introducing aging model of stress erosion of cohesion c and considering in-situ stress release of aging model,this paper put forward two kinds of analytical solution of tunnel in non-uniform stress field which consided the unloading mechanical response of tunnel surrounding rock. Then it analysis and forecasts the evolution of aging mechanical response of tunnel surrounding rock.