A new analytical solution for deep-buried circular cavern with anchor reinforcement under seepage field

Abstract

This paper presents a new method for assessing the stability of an underground cavern with anchor reinforcement under the seepage field. Firstly, the reinforcement effect of the anchor is considered as a set of clamping forces acting on both sides of the anchored rock mass, besides, whose strength parameters are also considered to be improved. Secondly, a mechanics model for a deep-buried circular cavern with anchor reinforcement under the seepage field is established, and the analytical solution incorporating the characteristics of dilatancy and strain softening of the surrounding rock are derived based on the unified strength theory. Finally, the validity and accuracy of the present solution are examined via comparison with published researches and field monitoring data. Subsequently, extensive parameter investigation is performed to systematically discuss the influence of the intermediate principal stress, dilatancy, strain softening, and seepage force on the cavern deformation and study the variation of the axial force of anchors. The results show that the surrounding rock stresses increase significantly but its radical displacement and the anchor axial force decreased as the intermediate principal stress coefficient increases. With the increase in dilatancy angle, the surrounding rock radial displacement and the anchor axial force increase sharply, but the plastic zone radius and the stresses are almost constant. Moreover, considering the seepage field, the peak value of maximum tangential stress and the stresses in the elastic zone increases but the radial stress in the plastic zone decreases, and the radial and tangential stress distributions are no longer asymptotic with the initial ground stress.