Analytical Calculations For Sress-Displacement Of Deep Circular Tunnels In Elastic-Viscous-Plastic-Brittle Ground And Plastic Zone Of Deep Tunnels Of Arbitrary Cross Sections

Surrounding rock stress and displacement of the analytical solution can clearly and accurately reflect the changing rule of the stress and displacement, and can be gained by analyzing the calculation results of different parameters. The regularity of But there is no in view of the existing embedded tunnel surrounding rock stress and displacement of the analytical solution of the system and comparative analysis, and numerical solution is proved at the same time, the existing analytical solution in some place where it is not clear or even unreasonable needs further clarification and correct. Deep buried tunnel with circular cross section, the author of this paper play-stick-plastic-brittle stress and displacement of analytic calculation and numerical solution and analytical solution for comparative analysis, and use the piecewise smooth section elastic solution to predict the plastic zone. The main research contents and results were as follows:(1) according to uniform axisymmetric initial stress field in deep buried tunnel with circular cross section, the surrounding rock to obey four different combinations of yield criterion and the elastoplastic model, including:Moore-coulomb yield criterion and ideal elastic-plastic zero plastic volume strain model, Moore-coulomb yield criterion and play-brittle plastic flow model and relevant nondimensional hawk brown yield criterion and ideal elastic-plastic unrelated flow model, the hawk-brown yield criterion and play-brittle plastic not related flow model, analytical method and numerical solution and comparison analysis. Among them, the analytical solutions when subject to zero plastic volume strain model and elastic brittle plastic model, the numerical simulation software of no built-in these models, the numerical solution using the built-in ideal elastic-plastic model and the analytical solution, such as analysis of surrounding rock brittleness of the impact of differences.With the ideal elastic-plastic zero plastic volume strain model, compared to the ideal elastic-plastic model is identical to that of the surrounding rock stress of radial displacement and relatively large, so is the ideal elastic-plastic model should be safe.And the ideal elastic-plastic model is different, when the bomb-brittle plastic model, yield criterion of strength parameters can reduce residual value for it. So both obey Moore-coulomb yield criterion and obey the hawk-brown yield criterion, compared with the ideal elastic-plastic model, the bomb-brittle plastic model (brittle) plastic zone radius, radial displacement are relatively large, and the (crisp) radial stress of plastic zone and the ring to stress are smaller.(2) according to uniform axisymmetric initial stress field in deep buried tunnel with circular cross section play-brittle-viscoplastic model analytical solution, first of all, through the finite difference calculation on initial undetermined function of the plastic zone of transcendental equation, the approximate solution of undetermined function is obtained; Then, to solve and analyze the plastic zone radius changes with time, surrounding rock stress and relative displacement of an arbitrary point changes with time, at any time of surrounding rock stress and relative displacement with the changes of distance; Finally, stick to Ben haim play-brittle plastic model analytical solution and numerical solution of the comparative analysis, as there is no built-in numerical simulation software of the model, thus numerical solution using the built-in maxwell viscoelastic plasticity model and the analytical solution, such as analysis of surrounding rock brittleness of the impact of differences.Play-brittle-viscoplastic model dynamic plastic zone of surrounding rock ring of an arbitrary point to stress with the time change is discrete, the transient radius of plastic zone expansion to the instantaneous jump point; Any time tangential stress of surrounding rock with the change of distance is discontinuous, in the initial radius of plastic zone and the transient radius of plastic zone two jumps.(3) for uniform initial stress field of buried deep within the boundary of piecewise smooth section tunnel elastic solution of complex potential function, first of all, with elliptic tunnel as an example to prove when the mapping function of the coefficient values make the tunnel section vertical symmetry axis and longitudinal axis Angle too, the tunnel after the clockwise tunnel cross section of the vertical axis of symmetry and coordinate longitudinal axle load, the values of stress and displacement, and the mapping function of the coefficient values make the vertical axis of symmetry of tunnel cross section and the stress and displacement are obtained by longitudinal axle load timeliness of coordinate. Then, analyze and analytical calculation and numerical analysis.(4) the uniform initial stress field of buried deep within the boundary of piecewise smooth section tunnel elastic solution of the analytical calculation results to the yield criterion to predict the plastic zone, and the different cross section of the tunnel prediction solution and analytical solution and numerical solution and prediction under different initial stress condition were analyzed. Through calculation contrast can be seen, this prediction of plastic zone tunnel method has certain limitations, as the cohesive force and Angle of internal friction values is opposite bigger, theoretical predictions of plastic zone is relatively accurate.