Taking a newly built extra-long highway tunnel in Guangdong as an example,the deformation of and the stress in the supporting structure in the cave disposal section thereof was analyzed with three dimensional finite element software (FLAC3D),and then the effect of disposal structure on the deformation of and the stress in the tunnel was discussed.The study result shows that,in the case of tunneling for three-lane highway,the laws of surrounding displacement deformation is as follows:vault settlement ＞ inverted arch uplift ＞ horizontal convergence;the cave disposal structure transmits the rock force at both sides and maintains the rock stability at the cave,which is important to reduce the deformation of tunnel vault,but has little effect on the horizontal convergence and inverted arch uplift;after the cave is disposed,there exists stress concentration at the edges and corners inside,leading to instability easily,then second collapse may occur.Therefore,the related measure should be taken to dispose the interior of cave to ensure the safety of tunnel structure.%以广东某新建公路长大隧道工程为例,运用三维有限元软件(FLAC3D)对该隧道溶洞处治段支护结构的变形及受力进行了分析,探讨了溶洞处治结构对隧道变形及受力的影响.研究结果表明:三车道公路隧道开挖中,隧道周边位移变形规律为:拱顶沉降＞仰拱隆起＞水平收敛;溶洞处治结构传导了两侧围岩作用力,维持了溶洞处围岩稳定性,对减小隧道拱顶变形意义重大,但对隧道水平收敛及仰拱隆起基本无影响;溶洞处治后,溶洞内部棱角处存在应力集中现象,易发生失稳,导致溶洞的二次坍塌,为保证隧道结构的安全,应对溶洞内部进行相应的处理.
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