Influence of tunnel wall roughness and localized stress concentrations on the initiation of brittle spalling
Influence of tunnel wall roughness and localized stress concentrations on the initiation of brittle spalling
复制标题
隧道壁粗糙度和局部应力集中对脆性剥落萌生的影响
DOI：
10.1007/s10064-015-0816-8
复制
发表时间：
2016-11-01
影响因子：
4.2
通讯作者：
Cai, Ming
中科院分区：
文献类型：
--
作者：
Guo, Songfeng;Qi, Shengwen;Cai, Ming
当基坑附近的应力达到原位强度时，大块硬岩发生脆性破坏。在回顾已发表的论文后，我们发现两种方法，一种使用UCS（field）（ci）ae 0.45 UCSlab，另一种使用UCS（field）（cd）ae 0.8 UCSlab，已用于估计块状岩石的原位强度，其中UCSlab和UCSlab分别是现场和实验室单轴抗压强度，上标表示由裂纹损伤应力或裂纹萌生应力定义的UCS场。在这项研究中，一个连续介质模型，考虑“建成剖面”，以模拟脆性岩石破坏在两个正交的隧道在420级的加拿大原子能有限公司（AECL的）地下研究实验室。从在UCS（场）（cd）下的原位强度的模拟获得的结果似乎比在UCS（场）（ci）下的原位强度更好地捕捉实际岩石条件。开孔壁粗糙度对大块硬岩的脆性破坏有很大影响。结果表明，与光滑边界条件相比，粗糙边界条件下应力集中，压应力加载产生的拉应力会促进岩石层裂破坏。如果忽略开孔粗糙度的影响，将低估UCSfield的现场单轴抗压强度.
Brittle failure of massive hard rocks occurs when the stress near the excavation reaches the in situ strength. After reviewing published papers, we found that two approaches, one using UCS (field) (ci) ae 0.45 UCSlab and the other using UCS (field) (cd) ae 0.8 UCSlab, have been used to estimate the in situ strength of massive rock, where UCSfield and UCSlab are the field and laboratory uniaxial compressive strengths, respectively, and the superscripts denote UCSfield defined by the crack damage stress or crack initiation stress. In this study, a continuum model considering the "as built profile" was constructed to simulate brittle rock failure in two orthogonal tunnels in the 420 level of Atomic Energy of Canada Limited's (AECL's) Underground Research Laboratory. Results obtained from the simulation with in situ strength at UCS (field) (cd) seem to capture actual rock conditions better than that with the in situ strength at UCS (field) (ci) . Opening wall roughness has a great influence on the brittle failure of massive hard rocks. It was found that compared with the smooth boundary condition, stress can concentrate around the rough boundary and the induced tensile stress driven by compressive stress loading can promote rock spalling failure. If the opening roughness is overlooked, the field uniaxial compressive strength of UCSfield will be underestimated.