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岩体中的节理一般是满足一定统计规律的随机网络。利用UDEC实现了蒙特卡罗随机节理网络,在此基础上考虑了隧道的开挖和初喷加固。设计了未采取初喷加固方案,采取初喷加固时初喷混凝土黏聚力为0.1、0.2、0.4、0.6、0.8MPa计算方案和初喷混凝土厚度为10、15、20、25、30cm计算方案,计算对比不同工况的塑性区、应力和监测点位移值,发现:不采取初期衬砌,隧道的破坏形式主要是洞顶掉块;初喷厚度一定时,初喷接触面材料黏聚力越低块体越易脱落,超过0.4MPa时则围岩稳定;初喷接触面材料强度一定时,初喷厚度对围岩稳定性有影响,存在临界厚度,过大过小均不利于隧道围岩稳定。这些特征值可以作为同类围岩条件下隧道设计的极限值。
Joints in rock mass are generally random networks that satisfy certain statistical laws. The UDEC is used to realize the Monte Carlo stochastic joint network. On the basis of this, tunnel excavation and initial shotcrete reinforcement are considered. Designed not to take the first shotcrete reinforcement scheme, the first shotcrete reinforcement to take the first shotcrete cohesion 0.1,0.2,0.4,0.6,0.8 MPa calculation program and the initial shotcrete thickness of 10,15,20,25,30 cm calculation program , Calculated and compared plastic zone, stress and displacement of monitoring point under different working conditions. It is found that the main failure mode of the tunnel is not the initial lining; The lower the block is, the easier it is to fall off. When it exceeds 0.4MPa, the surrounding rock is stable. When the strength of the initial spray contact surface material is constant, the initial spray thickness has an impact on the stability of the surrounding rock and the critical thickness exists. stable. These eigenvalues can be used as the limit values for tunnel design in similar surrounding rock conditions.