米拉山隧道凝灰岩开挖与支护力学特性研究  

Study on Mechanical Property of Tuff Excavation and Supporting in Mila Mountain Tunnel

作　　者：杨文东[1] 夏杰 刘继国[2] 谢全敏[1] 陈必光[2] 

机构地区：[1]武汉理工大学土木工程与建筑学院,湖北武汉430070 [2]中交第二公路勘察设计研究院有限公司,湖北武汉430010

出　　处：《公路交通科技》2018年第2期79-85,94,共8页Journal of Highway and Transportation Research and Development

基　　金：国家自然科学基金项目(51779197);西藏自治区重点科研项目(2016XZ01G31)

摘　　要：通过对实测数据分析可知,米拉山隧道凝灰岩遇水软化对围岩的变形影响很显著,为此,采用数值模拟方法对米拉山隧道凝灰岩开挖与支护力学特性进行了研究,获得了在不同时期围岩遇水软化和各分步开挖阶段围岩的位移、应力场变化规律,支护衬砌结构的变形、应力分布及内力分布情况。围岩遇水软化后,由于隧道的变形,锚杆与围岩发生相对滑动,锚杆嵌入隧道围岩,隧道变形大的部位也是锚杆受力大的部位,同时该部位锚杆与围岩的相对滑动也最大。隧道下台阶一次性开挖后施作的锚杆受力左右成对称分布,下台阶左右分步开挖施作的锚杆受力成不对称分布,后面施作的锚杆受力小于前面施作的锚杆受力。隧道围岩遇水软化后初期支护发生整体下沉,沉降量由拱脚向拱肩逐渐增大,拱顶沉降相对小于拱肩沉降;通过对不同阶段隧道围岩遇水软化下二次衬砌和仰拱的受力分析,发现在围岩软化的情况下进行隧道的开挖时,下台阶一次性开挖、仰拱一次性施作对隧道的安全性和稳定性方面都有提高,并得出不同阶段隧道围岩遇水软化隧道在后期运营阶段均处于安全状态。By analyzing measured data, a conclusion can be drawn that the water softening of tuff in Mila mountain tunnel has great effect on the deformation of the surrounding rock. So, the mechanical property of tuff excavation and supporting in Mila mountain tunnel is researched by using the method of numerical simulation, the variation rules of displacement and of stress field of surrounding rock, the deformation, stress distribution and inner force distribution of the lining structure in different water softening periods and different excavation steps are obtained. After the surrounding rock water softened, there is a relative slide between the anchor bar and surrounding rock due to the tunnel deformation. The anchor bar embedded in the surrounding rock of the tunnel, and the place that has a heavy deformation in tunnel is also a place that has been stressed heavy of the anchor bar, at the same time, there has a largest relative slide between the anchor bar and the surrounding rock in that place. The force of the anchor bar is a symmetrical distribution after once lower half excavation of the tunnel, while the force of the anchor bar is asymmetrical distribution after left and right step- by-step lower half excavation. The force of the later supported anchor bar is smaller than that of the earlier supported anchor bar. The early supporting would be sink entirety after the tunnel＇s surrounding rock water softened, the settlement is gradually increased from springing to spandrel, and the settlement of vault is relatively smaller than that of the spandrel. Through analyzing the stresses of the secondary lining and theinverted arch with water softened tunnel＇s surrounding rock in different steps, it is found that （ 1 ） when the tunnel is excavated under the condition of softened surrounding rock, the once lower half excavation and the once inverted arch construction can improve the safety and stability of the tunnel; （2） the tunnel with water softened surrounding rock in different periods is safe in its later s

关 键 词：隧道工程 力学特性 监测与数值分析 凝灰岩 开挖与支护 软化 

分 类 号：U455.7[建筑科学—桥梁与隧道工程]