连拱隧道围岩变形和破坏形态的DDA分析

Analysis on Deformation and Failure Mode Characteristics of Surrounding Rock of Multi-arch Tunnel by DDA Method

摘要:

连拱隧道围岩一般为由节理结构面相互切割的非连续岩体，利用非连续性分析方法研究这类围岩的变形和破坏形态可以更好地反映工程实际情况。采用非连续变形分析方法DDA，对金鸡山连拱隧道围岩的变形和破坏过程进行了模拟，将整个变形破坏过程划分为了3个阶段：中墙上方岩体变形、地表下沉、滑移面产生阶段、隧道左右洞两侧滑移带（或滑移面）的形成阶段以及中墙顶部块体失稳、隧道上方岩体快速塌落阶段。研究了金鸡山隧道浅埋围岩和深埋围岩的变形破坏特征，其中边墙部位、靠近中墙的内侧拱顶或拱肩部位、外侧拱肩部位会首先受到变形破坏。

关键词:连拱隧道;DDA分析;围岩变形;节理;破坏形态

Abstract:

The surrounding rock of multi-arch tunnel is intermittence jointed rock masses in most cases; it’s more realistic to analyze the deformation and failure mode characteristics of this kind of rock with discontinuous deformation analysis (DDA) method. The deformation and failure process of surrounding rock of Jinjishan multi-arch tunnel was simulated and the whole failure process was divided into 3 stages: rock deformation, surface subsidence and slip plane appearing above the mid-partition; slip planes (or bands) forming on both sides of tunnel; the rock mass instability above the mid-partition and rapid collapsing of rock mass above the tunnel. The paper studied the deformation and failure characters of shallow and deep surrounding rock in Jinjishan tunnel with the conclusion that the sidewall of the tunnel, the dome or the inside spandrel close to mid-partition and the outside spandrel would be first deformed.

Key words:multi-arch tunnel; DDA; surrounding rock deformation; joint; failure mode