Analysis Of Elastic-plastic Stress And Displacement For Circular Pressure Tunnel

The pressure tunnel is one of common structures in civil engineering, which is often designed to be circular and with a lining. At present, investigations of circular pressure tunnel are focused on some aspects, such as different disposal of lining, choice of strength criterion, change of principal stress orders in different engineering conditions, effect of seepage volumetric force and hole hydraulic pressure, and so on, conclusions of which have differences with the actual conditions. In result, based on unified strength theory, investigations stress field and displacement filed on circular pressure tunnel have important academic and engineering application significance, considering principal stress orders in different engineering conditions, rock strain-softening, shear dilation and seepage effect, et al.Aim to a circular water pressure tunnel with lining, the research contents of this paper are as follows:Utilizing unified strength theory and basal knowledge of water pressure tunnel, equations of unified strength theory in plane-strain state are deduced. Considering rock strain-softening and effect of different stress conditions in construction stage and operating period, expressions of initialized and subsequent yield surfaces in different engineering conditions are deduced. Based on the plane-strain state unified strength theory and elastic-brittle-plastic strain-softening model, unified solutions of stress and displacement on hydrated surrounding rock, with shear dilatation and strain-softening characteristic, and elastic lining are presented, considering different hydraulic pressure distributions in construction stage and operating period. In operating period, solutions are built on elastic and elastic-plastic state of hydrated surrounding rock in construction stage. The effects of ratio of penetrability coefficient( k d /k c), strength theory parameter(b ), softening characteristic parameters( c₁,?1 ), shear dilatation characteristic parameter(h ) on stress and displacement of surrounding rock and lining are discussed, in construction stage and operating period, respectively.Via deducing unified solutions of stress and displacement on hydrated surrounding rock and lining in construction stage and operating period, different mechanics behaviors of tunnel and parameter effects are presented in different engineering conditions, which have an important practical value for academic investigation and engineering application.