Analytical solutions of hydraulic tunnels considering strain softening, shear dilation and seepage

Based on the unified strength theory and the elastic-brittle-plastic softening model,analytical solutions of stress and tunnel wall displacement for circular hydraulic pressure tunnels are deduced considering the principal stress orders under different engineering conditions,rock strain softening,shear dilation and seepage.Comparisons are made between the results obtained in this paper and those of the traditional methods through an engineering example.It can be found that it more accords with the engineering practice to consider the variation of the maximal principal stress and volumetric force of seepage.The effects of the unified strength theory parameter,strain softening characteristic parameters and shear dilation characteristic parameter on the tunnel tangential stress and tunnel wall displacement are discussed.In tunnel design,the unified strength theory parameter should be reasonably adopted according to surrounding rock material properties.The increasing effects on the tunnel tangential stress and tunnel wall displacement also should be considered with the decrease of the strain softening characteristic parameters and shear dilation characteristic parameter.