含结构面隧洞围岩损伤演化和时效破坏的数值模拟研究

发布时间：2018-05-08 21:04

本文选题：隧洞围岩 + 长期强度　；参考：《大连理工大学》2015年硕士论文

【摘要】：基于对岩石长期强度的认识,从岩石的强度、弹模等物理力学性质受环境因素影响随时间劣化以及岩石内部细观损伤积累的角度出发,通过引入岩体细观表征单元体的强度退化方程,应用RFPA数值模拟方法,研究隧洞围岩的损伤演化与时效破坏机制。首先,模拟了岩石的单轴压缩蠕变试验和隧洞的时效变形破坏过程,并分别与相应的物理试验结果进行了对比,数值模拟结果很好地反映了软弱岩石典型蠕变的三阶段：初始、稳定和加速阶段；隧洞数值模拟试验得到了拱顶、拱底以及两侧帮的时效变形特征曲线,与实际物模试验结果表现出了较好的一致性。作为参数分析,进一步模拟分析了侧压系数对隧洞时效损伤破坏特性的影响,模拟结果显示,随着侧压系数的增大,隧洞左右边墙间的收敛位移逐渐增大,而隧洞拱顶拱底间的闭合位移随侧压系数的增大逐渐减小,并对隧洞围岩的局部的细观损伤演化过程及宏观时效破坏模式做出了清晰的解释。其次,研究了软弱夹层的分布对隧洞围岩损伤演化和时效破坏的影响,发现隧洞周围应力场和位移场分布的对称性在软弱夹层的影响下发生明显的改变,出现向软弱夹层附近“迁移”的现象,使得洞室与软弱夹层之间形成高应力集中区,进而造成临近软弱夹层一侧岩体的位移和破坏程度明显增大；由于软弱夹层分布位置的不同,隧洞围岩的时效损伤破坏模式也出现明显的差异。作为参数分析,进一步模拟分析了软弱夹层厚度对隧洞围岩时效损伤破坏特性的影响,模拟结果显示,随着软弱夹层厚度的增加,隧洞的拱顶、两侧边墙位移不断地增大,隧洞的破坏程度也越来越严重,夹层厚度对隧洞时效损伤破坏的影响显著增大。进而,模拟分析了节理分布倾角对隧洞围岩的损伤演化和时效破坏机制的影响,发现在节理的影响下,隧洞开挖后,围岩的应力分布规律发生明显的改变；节理为水平节理时,隧洞以两侧边墙片帮破坏为主；随着节理面倾角的变化,隧洞围岩的的时效损伤破坏模式也发生了明显的变化,隧洞损伤破坏区随节理倾角的增大相应旋转；当节理方向竖直时,隧洞破坏主要集中于拱顶和拱底部位,出现了严重的冒顶和底鼓现象。同时,在节理面的影响作用下,隧洞周围围岩的位移发生明显的变化,并且随着节理倾角的增大,隧洞位移呈现出先增后减的大致趋势。最后,以伊朗Taloun公路隧道的服务隧洞为工程背景,对其进行了损伤演化和时效破坏特性的实例分析。
[Abstract]:Based on the understanding of the long-term strength of rock, the physical and mechanical properties such as rock strength and elastic modulus are affected by environmental factors and the accumulation of meso damage in rock. By introducing the strength degradation equation of the rock mass characterization unit, the damage evolution of the tunnel surrounding rock is studied by the RFPA numerical simulation method. First, the uniaxial compression creep test of rock and the aging deformation and failure process of the tunnel are simulated, and the results are compared with the corresponding physical test results respectively. The numerical simulation results reflect the three stages of the typical creep of the soft rock: initial, stable and accelerating stages; the numerical simulation test of the tunnel has been obtained. The aging deformation characteristic curve of the vault, arch bottom and both sides shows good consistency with the actual model test results. As a parameter analysis, the influence of the side pressure coefficient on the damage characteristics of the tunnel aging damage is further simulated and analyzed. The simulation results show that the convergence displacement between the left and right side walls of the tunnel is increased with the increase of the lateral pressure coefficient. Gradually, the closure displacement between the arch top and the arch of the tunnel gradually decreases with the increase of the lateral pressure coefficient, and makes a clear explanation for the local mesoscopic damage evolution process and the macroscopic aging failure mode of the tunnel surrounding rock. Secondly, the influence of the distribution of the weak interlayer on the damage evolution and the aging damage of the tunnel surrounding rock is studied, and the tunnel surrounding the tunnel is found to be around the tunnel. The symmetry of the distribution of stress and displacement fields is obviously changed under the influence of weak intercalation, and the phenomenon of "migration" to the weak intercalation causes the formation of high stress concentration zone between the cavern and the weak intercalation, and the displacement and damage degree of the rock mass near the weak intercalation is obviously increased, and the weak interlayer is divided into the weak intercalation. As a parameter analysis, the influence of the thickness of the weak interlayer on the damage characteristics of tunnel surrounding rock is further simulated and analyzed. The simulation results show that the displacement of the vault and side wall of the tunnel increases continuously with the increase of the thickness of the weak interlayer. The damage degree of the cave is becoming more and more serious, and the influence of the thickness of the interlayer on the damage and damage of the tunnel is significantly increased. Then, the influence of the joint dip angle on the damage evolution and the aging failure mechanism of the tunnel surrounding rock is simulated and analyzed. It is found that the stress distribution law of the surrounding rock changes obviously after the tunnel excavation. In the case of horizontal joints, the tunnel is mainly damaged by the side wall of the tunnel. With the change of the angle of the joint, the damage failure mode of the tunnel surrounding rock has also changed obviously. The damage zone of the tunnel rotates with the increase of the joint dip. When the joint direction is vertical, the tunnel failure is mainly concentrated on the vault and the bottom of the arch. There is a serious roof and bottom drum phenomenon. At the same time, under the influence of the joint surface, the displacement of the surrounding rock around the tunnel is obviously changed, and with the increase of the joint inclination, the tunnel displacement presents a general tendency to increase first and then decrease. Finally, the damage performance of the service tunnel of the Iran Taloun highway tunnel is taken as the engineering background. Case analysis of chemical and aging failure characteristics.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

【参考文献】