摘要
为研究浅埋隧道掌子面稳定性及获取精细化的破坏模式,提出了一种上限有限元非结构化网格自适应加密策略。以单元耗散能权重指标作为网格自适应加密评判准则,该策略同时兼顾了单元尺度与塑性应变。应用高阶的6节点三角形单元并建立上限有限元线性规划模型,以多次反复计算和网格加密的方式实现了二维自适应上限有限元分析并编制了计算程序。利用条形基础地基极限承载力课题,从上限解精度和网格加密形态方面验证了该程序的有效性。针对浅埋隧道掌子面稳定性问题,展开多参数条件下的自适应上限有限元计算,分析了网格加密过程中单元总数与上限解精度的关系,列出不同隧道埋深和内摩擦角对应的隧道掌子面稳定性临界值的上限解,揭示出掌子面稳定性变化规律及精细化的破坏模式。
A finite element upper bound solution with unstructured mesh adaption to refinement criterion is presented to evaluate stability of shallow tunnel face and obtain accurate failure mechanism. Weight indexes of element energy dissipation are regarded as mesh adaption refinement evaluation criterion considering element scales and plastic strain. A two-dimensional finite element upper bound solution model with six-nodal triangular element and linear programming is compiled. It can perform mesh adaption with repeated mesh refinement during a series of computational process. Using strip foundation ultimate bearing capacity of foundation, the solution is verified to perform effectively in the aspects of accuracy of upper bound values and mesh features. Numerical calculation analysis is done using the finite element upper bound solution with mesh adaption. Different parameters are adopted to evaluate stability of shallow tunnel face. The relationship between element quantity and accuracy of upper bound value is analyzed during process of mesh refinement. The upper bound solutions of stability critical values of tunnel face at different depths and internal angles are demonstrated. Failure mechanism and variation law of stability of tunnel face are revealed.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2015年第1期257-264,共8页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51008309)
中南大学中央高校基本科研业务费专项基金(No.2014zzts045)
关键词
浅埋隧道
掌子面稳定性
上限有限元
6节点三角形单元
破坏模式
网格自适应
shallow tunnel
face stability
finite element upper bound solution
six-nodal triangular element
failure mechanism
mesh adaptation
