大跨隧道CD法施工稳定性与力学特征  

Analysis of Stability and Mechanical Characteristics of Large Section Tunnel by CD Excavation Method

作　　者：郝德亮 Hao Deliang(China Railway 16th Bureau Group Road&Bridge Engineering Co.,Ltd.Beijing 101500,China)

机构地区：[1]中铁十六局集团路桥工程有限公司,北京101500

出　　处：《广东土木与建筑》2020年第5期44-47,共4页Guangdong Architecture Civil Engineering

基　　金：国家自然科学基金资助项目(51408216,51308209)。

摘　　要：为研究超大跨隧道施工安全性,结合某隧道大跨段,基于强度折减上限有限元与下限有限元法,分析大跨隧道在CD工法下各开挖步下的上下限稳定系数,以及能量耗散特征,并研究围岩条件以及跨对稳定性的影响,进而分析其变形受力特性。结果表明:随着隧道跨度增大,整体安全系数降低;围岩条件差,整体安全系数降低;隧道开挖部增大,开挖断面变大,安全系数降低。但各部安全系数均大于1.5,表明采用CD法施工整体安全性满足要求。开挖跨度越大,围岩变形越大;各施工步下,较大值发生在开挖部范围周边的中部;由于竖撑的约束,拱顶与仰拱位移较小;竖撑能很好控制变形。中墙轴力较大,且存在横向弯矩,易发生失稳,建议加强横向联系或约束。拱顶、边墙、拱脚及仰拱等部位应力较集中,施工应注意,保证锁脚锚杆等安设质量。In order to study the construction safety of super long-span tunnel,combined with the tunnel construction,based on the upper limit finite element method and the lower limit finite element method of strength reduction,this paper analyzes the upper and lower limit stability coefficient and energy dissipation characteristics of the large-span tunnel under the CD method,and studies the influence of surrounding rock conditions on the stability of the tunnel,and then analyzes its deformation and stress characteristics.The results show that with the increase of tunnel span,the overall safety factor decreases;with the poor surrounding rock conditions,the overall safety factor decreases;with the increase of tunnel excavation part,the excavation section becomes larger,and the safety factor decreases.However,the safety factor of each part is greater than 1.5,which indicates that the overall safety of CD construction meets the requirements.The larger the excavation span is,the larger the deformation of the surrounding rock is;in each construction step,the deformation occurs in the middle of the excavation part;due to the constraint of the vertical support,the displacement of the arch crown and the inverted arch is small;the vertical support can control the deformation well.The axial force of vertical bracing is large,and there is transverse bending moment,it is easy to lose stability,so It is suggested to strengthen the lateral restraint of vertical bracing.The stress of vault,side wall,arch foot and invert is relatively concentrated,so attention shall be paid during construction to ensure the installation quality of anchor bolt.

关 键 词：隧道工程 CD工法 稳定分析 力学特性 

分 类 号：U455.4[建筑科学—桥梁与隧道工程]