质疑卡斯特纳公式
首发时间:2019-03-29
摘要:隧道围岩的应力及变形是隧道力学中的基本问题,它直接影响到隧道的安全评价及施工支护措施。上世纪50年代提出的卡斯特纳公式,描述了圆形隧道的塑性区半径和塑性区的应力分布规律,公式已成为隧道力学分析的理论基础。本文通过塑性力学加卸载准则和FLAC数值计算,以满足莫尔-库伦准则的理想弹塑性材料为例,证明了隧道的支护过程是塑性力学中的卸载过程,支护后的围岩应力增量及位移增量符合弹性力学规律;卡氏公式只适用于开挖后支护前的阶段,不适用于有支护应力作用时的隧道力学计算。沿袭了60多年的卡氏公式是错误的。
For information in English, please click here
Question Kastner formulae of circular tunnel
Abstract:Stress and deformation of surrounding rock are basic issues in tunnel engineering, directly affecting the safety evaluation and the support or lining measures to a tunnel. Kastner formulae proposed in 1950s describe the plastic zone range of a circular tunnel and the stress distribution in plastic zone, and have served as the theoretical basis of tunnel analysis in past decades. Supposing the surrounding rock is ideal elastic-plastic material with Mohr-Coulomb or Mises criterion, we proved that the support process to a circular tunnel is an unloading process in terms of plastic mechanics. The conclusion was verified by FLAC calculation. Both the stress increment and the displacement increment of surrounding rock in support stage are consistent with the elasticity theory. Therefore, Kastner formulae are only applicable to the excavation stage of tunnel, not to the support stage.
Keywords: tunnel Kastner formula loading criterion plasticity analysis
基金:
引用
No.****
动态公开评议
共计0人参与
勘误表
质疑卡斯特纳公式
评论
全部评论0/1000