Distribution of Stress Around Underground Excavations
摘要
This chapter investigates the distribution of stress around subterranean excavations, focusing on circular shafts and tunnels. It introduces the convergence-confinement method to accurately analyze stress, particularly near shafts, and presents stress equations in cylindrical coordinates. Case studies demonstrate how stress levels vary from the periphery of shafts to deeper zones, offering valuable insights for designing rock structures. The analysis extends to elastic strains around circular tunnels, examining deformation equations governing sidewalls and roofs. Positive values signify inward deformation, while negative values indicate outward movement, thereby affecting tunnel stability. Stress distribution in elliptical openings is explored, featuring critical equations essential for stability assessments and practical engineering implications. Additionally, the chapter delves into stress patterns around ovaloidal and rectangular openings, revealing distinct concentration patterns. Ovaloidal shapes typically exhibit maximum stresses near junctions, influenced by their width-to-height ratios. Meanwhile, rectangular openings, designed with rounded corners to reduce stress concentrations, display varying stress distributions determined by their aspect ratios and the type of stress field. Furthermore, the chapter investigates stress concentrations in openings inclined at angle δ, where critical stress levels vary based on δ and the prevailing stress field type (M = 0, 1/3, 1). These findings contribute to establishing optimal design criteria for openings within rock formations.