摘要
为揭示隧道锚围岩夹持效应的力学机制,认识隧道锚围岩破坏模式并确定极限抗拔能力,进行圆台形锚体和圆柱形锚体的夹持效应对比试验。试验选择在普立特大桥隧道锚碇区勘探斜洞的2条平行支洞内进行,2种模型试体的侧面积和高度相同,以定量比较因夹持作用引起的隧道锚围岩极限抗拔能力的差别。试验结果表明,与圆柱形锚体模型相比,圆台形锚体模型因存在夹持效应,破坏前的变形量、围岩变形影响范围、破坏时的极限荷载明显增大。圆柱形锚体发生锚体混凝土与围岩接触面破坏,脆性破坏明显。圆台形锚体发生围岩沿不利结构面破坏,且破坏前经历了很长的屈服变形阶段,两者破坏模式完全不同。提出了夹持效应系数的概念及其计算模式,得出弹性阶段夹持效应系数、极限强度夹持效应系数分别为4.48,4.54。夹持效应产生的抗拔能力远远大于混凝土与岩体接触面的抗剪强度,是隧道锚抗拔能力的主要支撑。
In order to investigate the clamping effect and failure pattern of surrounding rocks as well as the limit of the pullout capacity of tunnel-type anchorage,field model tests on the conical frustum anchorage and cylindrical anchorage were conducted inside two parallel caves within the oblique cave of exploration in the anchorage area of Puli bridge. The side surface areas and the heights of two anchorage models are identical for quantitative comparing the differences of the clamping effect of surrounding rocks. The magnitude and the range of deformation before failure and the limit of load for the conical frustum anchorage are considerably larger than those for the cylindrical anchorage due to the clamping effect. For the cylindrical anchorage,brittle failure occurs remarkably in the contact area between the anchorage concrete and the surrounding rocks. For the conical frustum anchorage,the failure of the surrounding rocks occurs along the unfavourable fractures and experiences a long period of yielding deformation. The failure patterns for two anchorages are quite different. A concept of the coefficient of clamping effect and a corresponding method of calculation were suggested. The coefficients of clamping effect in the elastic period and at the period of strength limit are found to be 4.48 and 4.54 respectively. The pullout capacity induced by the clamping effect is significantly larger than the effect caused by the shear strength between the concrete and the rock mass. The clamping effect is the primary factor accounting for the pullout capacity of tunnel-type anchorage.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2015年第2期261-270,共10页
Chinese Journal of Rock Mechanics and Engineering
基金
长江科学院中央级科研院所基本业务费项目(CKSF2014066/YT)
云南省交通运输厅科技项目(2011(LH)12–a)
关键词
隧道工程
普立特大桥
隧道锚碇
现场模型试验
极限抗拔能力
夹持效应
围岩破坏模式
tunnelling engineering
Puli bridge
tunnel-type anchorage
field model test
ultimate pullout capacity
clamping effect
failure pattern of surrounding rock
