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为研究软弱岩体中隧道开挖引起的围岩失稳破坏特征以及锚杆的加固效应,以IV级围岩为参照对象,开展一系列无锚杆和有锚杆支护条件下的隧道开挖地质力学模型试验,并对拱顶围岩的位移、应力和宏观破坏形式的发展变化规律进行分析。研究结果表明:(1)隧洞开挖后,围岩破坏始自隧道两侧拱脚,渐次向上延伸并塌落成拱;(2)由于锚杆的悬吊挤压作用及其与岩层的组合梁效应,显著减少了拱顶岩体塌落范围;(3)锚杆通过对岩体施加黏锚力,提高了锚固范围内岩体的强度和韧性,有利于增强围岩的承载能力和抵抗变形能力;(4)锚杆支护对围岩应力分布起调节作用,使得围岩能在较高的能量状态下获得稳定平衡,并延缓了围岩进入“软化”阶段。上述研究成果可为软弱隧道围岩稳定性评价以及支护结构的设计与施工提供一定的借鉴和参考作用。
In order to study the characteristics of surrounding rock instability and damage caused by tunnel excavation in soft rock mass and the reinforcement effect of anchors, a series of tunnels with no anchor and bolt support are carried out with reference to IV grade surrounding rock Excavation of geomechanical model test, and analysis of the law of displacement, stress and macroscopic destruction of the vault surrounding rock. The results show that: (1) After the excavation of the tunnel, the failure of the surrounding rock begins with the arch legs on both sides of the tunnel and gradually extends upwards and collapses into an arch; (2) Due to the hanging extrusion of the rock bolt and its combination with the rock (3) The anchor rod can increase the strength and toughness of the rock mass in the anchorage area by strengthening the rock mass’s bearing capacity and resist the deformation Ability; (4) The bolt support plays a regulating role in the stress distribution of the surrounding rock, so that the surrounding rock can obtain a stable balance under the higher energy state and delay the surrounding rock to enter the stage of “softening”. The above research results can provide reference and reference for the evaluation of surrounding rock stability of soft tunnels and the design and construction of supporting structures.