岩溶区全断面开挖隧道围岩变形特性模拟

运用相似模型试验和数值分析手段对石灰岩地区公路隧道在全断面开挖过程中 ,隧道周边不同溶洞分布对隧道围岩变形特性的影响进行了系统的研究 ,模型实验结果与三维动态开挖过程的数值模拟结果较为吻合 .研究结果表明 :有溶洞的围岩在开挖前有较大的前期变形 ,溶洞引起的隧道围岩变形主要发生在分布有溶洞的断面开挖前和开挖瞬间 ;位于隧道顶部附近的溶洞对拱顶下沉位移的影响大于侧壁位移的影响 ;位于隧道侧面的溶洞主要引起隧道的整体侧向位移 ,使隧道处于偏压状态 ;隧道底部的溶洞对隧道的顶部和侧壁径向位移的影响较小

Deformation Modeling of Surrounding-rock during Full-face Excavation of Tunnel in Karst Regions

Based on the modeling test and numerical analysis of the full-face excavation tunnel in karst regions,a complete research on deformation properties of the surrounding rockmass is carried out.The results of physical model testing have good compatibility with those of numerical analysis.Research shows that the deformation of the surrounding rockmasses of tunnel varies with the karst cave size,situation and direction.The surrounding rock releases larger deformation before the excavating face arrives the karst caves.The releasing displacement of tunnel surrounding rock including karst caves appears mainly in the instant of excavating and in the front of excavating face.Karst caves on the top of tunnel have a larger influence on the arch-crown displacement than the arch-wall displacement.Karst caves in the side of tunnel cause the lateral deformation of the entire surrounding rock,and the slope pressure of highway tunnel.The influence of karst caves on the bottom of tunnel on the surrounding rockmasses is small during full-face excavating construction.