摘要
采用有限元法对隧道施工过程的支撑荷载法中的几个问题进行了详细的研究。讨论了释放荷载和支撑荷载的关系,分析了支撑荷载的大小、方向以及选取的部位对计算结果的影响;根据三维模型的计算结果确定了位移释放率,并据此得到了按平面应变模型模拟隧道施工过程时各施工阶段支撑荷载的大小。计算结果表明:在采用平面应变方法进行隧道施工过程的计算时,为了模拟开挖面的空间效应,在洞周施加的是支撑荷载而非释放荷载;在只有体积力和面力的情况下,支撑荷载可以采用被挖掉的岩土体的周边(内圈)节点的等效节点力,也可以取留下围岩周边(外圈)节点的等效节点力并反号,若洞周节点上有集中荷载,则支撑荷载必须采用前者;在台阶法施工中,采用变化后的洞周节点力作为下半断面支撑荷载的初始应力的方法,能够得到较满意的结果。
FEM was adopted to study the support load method of simulation in the process of tunnel construction.The relation of releasing load and support load was discussed.The influence of the size,the direction and the selected position of support load on calculated result was analyzed.Three-dimensional numerical model was adopted to simulate tunnel excavation and displacement releasing ratios were gained.Then,the values of the support load which applied the plane strain method to calculate the process of tunnel construction were confirmed.Calculated results show that when using the plane strain method to calculate the process of tunnel construction,the support load rather than the releasing load around the hole was applied to simulation of the spatial effect of excavation section.Only when numeration-system acts on body load and face load,the equivalent node forces of the circumference（inside track） nodes of rock elements which are wiped off can be used as support load;while reversing,the equivalent node forces of the circumference（outside track） of the remaining rock elements can also be used as support load.If there is concentrated load among the nodes of hole circumference,the former must be used.During the construction of step excavation method,if the method which uses changed node force in the hole circumference as initial stress of the support load of the underside half section is applied,the more satisfied result will be got.
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2010年第4期70-77,共8页
China Journal of Highway and Transport
基金
国家自然科学基金项目(50678077)
重庆市自然科学基金项目(CSTC2008BB6066)
重庆市教委科学技术研究项目(KJ090403)
关键词
隧道工程
开挖面效应
有限元法
支撑荷载
位移释放率
施工力学
tunnel engineering
effect of excavation section
finite element method
support load
displacement releasing ratio
construction mechanics
