浅埋公路隧道原位改扩建围岩变形破坏特征

Deformation and failure characteristics of surrounding rockin the reconstruction and expansion of shallow highway tunnel in situ

为了能使现役公路隧道满足当前交通量迅速增长的需求,需对原有隧道进行改建和扩建。以廷心隧道为工程背景,分析了现场工况及围岩变形破坏情况,采用力学分析软件GDEM数值模拟隧道原位扩建工程,选取不同围岩等级的力学参数,研究隧道围岩的应力、塑性变形、位移及形变等方面并分析围岩变形破坏规律。结果表明:围岩等级越低,拱顶、拱底以及衬砌上的竖向应力就越小,拱腰的竖向应力越大,隧道中间隔墙受到的破坏程度越大;在隧道扁平率的影响下,在隧道原位扩建时,隧道的拱顶、拱底以及拱肩的围岩变形相对较大,拱脚和拱腰的变形相对较小。

In order to make the existing highway tunnel meet the demand of the rapid growth of the current traffic volume,the original tunnel needs to be reconstructed and expanded.Taking the Tingxin Tunnel as the engineering background,the field working conditions and surrounding rock deformation and destruction are analyzed.The mechanical analysis software GDEM is used to simulate the in-situ expansion project of the tunnel.The mechanical parameters of different surrounding rock grades are selected to study the stress,plastic deformation,displacement and deformation of the surrounding rock of the tunnel and analyze the deformation and destruction laws of the surrounding rock.The results show that the lower the grade of surrounding rock,the smaller the vertical stress on the arch crown,arch bottom and lining,the greater the vertical stress on the arch waist,and the greater the damage degree of the tunnel middle partition;under the influence of the tunnel flattening ratio,when the tunnel is expanded in situ,the deformation of the surrounding rock of the tunnel’s arch crown,arch bottom and arch shoulder is relatively large,and the deformation of the arch foot and arch waist is relatively small.