Key principles of stress control method

Abstract

Underground excavation would cause two main excavation effects: (1) stress redistribution, including radial stress decrease and tangential stress concentration; and (2) surrounding rock degradation. Comprehensive consideration of excavation effects is crucial to prevent underground engineering disasters. However, the two excavation effects are not considered in the predominantly used Platts pressure arch theory, whereas the New Austrian tunneling method is focused on the full utilization of the strength of the surrounding rock. Construction designing using these methods could lead to disaster deep underground. Thus, in this study, the stress control method (SCM) was proposed to comprehensively consider the two excavation effects. The following two key SCM principles were introduced in this study: (1) adopt the largest possible prestressing force to increase the low radial stress caused by excavation; (2) timing of support should be as early as possible to minimize surrounding rock deterioration. The application principles of SCM in hard rock tunnels and soft rock tunnels are explained