Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation
Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation
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DOI：
10.1016/j.ijrmms.2004.02.003
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发表时间：
2004-07-01
影响因子：
7.2
通讯作者：
Eberhardt, E
中科院分区：
文献类型：
--
作者：
Diederichs, MS;Kaiser, PK;Eberhardt, E
在采用连续掘进技术（例如使用隧道掘进机或天井钻机设备）于脆性岩石中进行深部隧道挖掘时，所涉及的关键设计问题之一是产生表面剥落损伤和岩爆。本文描述了这一过程所涉及的机制。作为一种最坏情况的估计，可以使用基于完整测试样本的标准单轴抗压强度（UCS）的折减原位强度值来预测与这种现象相关的损伤起始和深度。对于花岗岩，为获得下限原位强度而应用于UCS的系数已多次表明在0.35 - 0.45的范围内。然而，该系数在不同的岩石类别中是不同的，并且必须针对每一类进行确定或估算。针对不同岩石类型和不同描述参数，基于UCS估算原位强度系数给出了经验性指导。概述了用于确定下限强度系数和上限原位强度的实验室测试程序。后一个阈值是基于由裂纹相互作用所定义的屈服。这些技术部分基于从离散单元微观力学实验和实验室测试结果得出的理论原理。描述了导致原位强度从由裂纹相互作用定义的上限下降到由裂纹萌生所限制的下限的机制。这些因素包括隧道引起的应力旋转对裂纹扩展、相互作用以及最终的合并和破坏的影响。给出了一个案例研究，说明了近工作面应力旋转的深远影响。（C）2004爱思唯尔有限公司。保留所有权利。
One of the critical design problems involved in deep tunnelling in brittle rock with continuous excavation techniques, such as those utilizing tunnel boring machines or raise-bore equipment, is the creation of surface spall damage and breakouts. The mechanisms involved in this process are described in this paper. The onset and depth of damage associated with this phenomenon can be predicted, as a worst case estimate, using a factored in situ strength value based on the standard uniaxial compressive strength (UCS), of intact test samples. The factor applied to the UCS to obtain the lower bound in situ strength has been shown repeatedly to be in the range of 0.35-0.45 for granitic rocks. This factor varies, however, across different rock classes and must be determined or estimated for each class. Empirical guidance is given for estimating the in situ strength factor based on the UCS for different rock types and for different descriptive parameters. Laboratory testing procedures are outlined for determining both this lower bound strength factor and the upper bound in situ strength. This latter threshold is based on the definition of yield based on crack interaction. These techniques are based, in part, on theoretical principles derived from discrete element micromechanical experimentation and laboratory test results. The mechanisms that lead to in situ strength drop, from the upper bound defined by crack interaction and the lower bound limited by crack initiation, are described. These factors include the influence of tunnel-induced stress rotation on crack propagation, interaction and ultimately coalescence and failure. A case study illustrating the profound impact of near-face stress rotation is presented. (C) 2004 Elsevier Ltd. All rights reserved.