论文部分内容阅读
为系统研究黄土隧道围岩破坏模式,采用颗粒流程序PFC2D进行离散元分析,离散元分析与现场实际的破坏模式基本吻合。对于黄土围岩而言,随着模型荷载逐渐增大,拱顶处先出现破坏,然后初始塌落拱出现,同时破坏向拱脚蔓延;塌落拱进一步向围岩深部发展。埋深是影响塌落拱发展的关键因素。当埋深较小时,形成蔓延至地表的贯通性裂缝甚至塌陷坑;当埋深足够大时,形成稳态塌落拱,与普氏理论类似。压力拱的发展与塌落拱相对应,隧道形成稳态的塌落拱,同时围岩的压力拱亦达到稳定,且拱部压力拱范围扩展较快;反之,即为破坏延伸至地表无法形成压力拱。离散元模型揭示了Ⅴ级围岩条件下大断面黄土隧道围岩破坏模式,对隧道支护参数的确定具有重要意义。
In order to systematically study the failure mode of surrounding rock of loess tunnel, the particle flow program PFC2D is used to carry out the discrete element analysis. The discrete element analysis is in good agreement with the actual failure mode of the site. For the loess surrounding rock, as the model load increases, the vault first appears the damage, and then the initial collapse arch appears, at the same time, the damage spreads to the arch foot. The collapse arch further develops to the surrounding rock. Depth of burial is the key factor affecting the development of slump arch. When the buried depth is small, the formation of penetrable cracks and even collapse pits that spread to the surface; when the depth is large enough, a steady-state slump arch is formed, similar to the Platts theory. The development of the pressure arch corresponds to the slump arch, the tunnel forms a steady state slump arch, meanwhile, the pressure arch of the surrounding rock also reaches a steady state, and the pressure arch range of the arch part expands rapidly; on the contrary, the damage can not extend to the surface Pressure arch. Discrete element model reveals the failure mode of surrounding rock of large-section loess tunnel under Grade Ⅴ surrounding rock conditions, which is of great significance for the determination of tunnel support parameters.