双连拱隧道结构内力样式及围岩稳定性模型试验研究

大型相似模型试验是双连拱隧道结构内力样式与围岩稳定分析研究的重要方法和手段之一。结合广州—惠州高速公路小金口双连拱隧道工程的修建,在II,III类围岩条件下,对双连拱隧道的施工方法和结构内力样式及围岩稳定进行了深入的研究工作。通过模型试验研究提出了一种新的施工方法——中导坑拓展法,这种施工方法对围岩的扰动少;同时采用三导坑法、双导坑法和中导坑拓展法3种施工方法进行模型试验研究。结果表明:周边最大径向位移发生于拱顶,其次为腰部;首次建立了双连拱隧道二次衬砌内力(轴力和弯矩)模型及围岩的稳定与变形的规律。这些研究成果对双连拱隧道的设计与施工具有重要指导作用。

MODEL EXPERIMENTAL STUDY ON STYLE OF STRUCTRUAL INTERNAL FORCE AND STABILITY OF SURROUNDING ROCK IN DOUBLE-ARCH TUNNEL

The large-scale model testing is one of the important methods to research style of structural internal force and stability of surrounding rock in double-arch tunnel. Based on the Xiaojinkou double-arch tunnel engineering of Guangzhou-Huizhou Expressway, the construction method, styles of structural internal forces and the stability of surrounding rock of double-arch tunnel are studied in detail under the condition of surrounding rock types II and III. By the model testing, a new method, i.e., central-heading expanding method, has been suggested. The surrounding rock is seldom disturbed when the tunnel is constructed by the central-heading expanding method. The three-heading method, double-heading method and central-heading expanding method have been studied by model testing. It is found that the maximum radial displacement take places at the arch and the sidewall. The model of internal force for the secondary lining and the laws of the deformation and the stability for the surrounding rock have been set up firstly in the double-arch tunnel. The results can offer references to the design and construction of double-arch tunnel.