围岩松动圈理论在某大断面隧道中的应用

Application of surrounding rock loosing-circle theory in a large profile tunnel

隧道开挖过程中,由于围岩受到扰动使得隧道周围形成了松动圈,松动圈的厚度对隧道的支护设计具有重要意义。基于Mohr-Coulomb(摩尔-库伦)强度准则,推导了隧道围岩松动圈半径的计算公式,并将其运用于大断面隧道工程实例中,分别计算了Ⅲ级、Ⅳ级、Ⅴ级围岩松动圈在不同埋深下的半径及其厚度。结果表明,隧道围岩松动圈厚度不仅与围岩级别有关,而且与地应力、支护压力以及隧道断面形式也相关。

In the process of tunneling excavation,due to the disturbance on surrounding rock,a loosing-circle is formed around the tunnel.The thickness of the loosing-circle is of great significance to the design of tunnel support.Based on the Mohr-Coulomb strength criterion,a calculating formula for radius of surrounding rock loosing-circle is derived,which is used to large profi le tunnel engineering practice.The radius and thickness of the loosing-circle of the grade III,grade IV and grade V under different depths are calculated respectively.The results show that the thickness of the surrounding rock loosing-circle is not only related to the surrounding rock category,but also related to the crustal stress,supporting pressure and the form of the tunnel profi le.