The volume increase of stress-fractured rock near an excavation results from three sources: (1) dilation due to new fracture growth, (2) shear along existing fractures or joints, and most importantly, (3) dilation due to geometric incompatibilities when blocks of broken rock move relative to each other as they are forced into the excavation. This dilation process is called Rock Mass Bulking, and is quantified by a Bulking Factor, defined as the percentage increase in radial deformation due to fracturing inside the failure zone extending to a depth of failure (df).; To develop a model for the calculation of the Bulking Factor ( BF), it is necessary to consider two options: (1) develop a non-continuum theory for rock mass behavior, or (2) adapt continuum mechanics principles to the problem and introduce an empirical component to calibrate the model. In this thesis, the second approach is adopted. A semi-empirical Rock Mass Bulking Model was developed, using as starting concepts dilation angle, plastic strain rates, effective deformation modulus, effective Poisson's ratio, Griffith locus, and the definition of BF introduced by Kaiser et al. (1996). The model was calibrated in order to obtain BFs in accordance with experimental data, and case studies were used to account for bulking around underground excavations. (Abstract shortened by UMI.)
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机译:开挖附近应力破裂岩石的体积增加来自三个方面:(1)由于新的裂缝增长而引起的膨胀;(2)沿现有裂缝或接缝的剪切;最重要的是,(3)由于块体几何不相容而引起的膨胀破碎的岩石在被迫进入挖掘过程时彼此相对移动。这种膨胀过程称为“岩体膨胀”,并通过膨胀系数来量化,膨胀系数定义为由于破坏区域内的破裂扩展到破坏深度而导致的径向变形的百分比增加( d f sub > italic>)。要开发用于计算膨胀因子( BF italic>)的模型,有必要考虑两个选择:(1)建立岩体行为的非连续理论,或(2)适应连续体力学原理解决问题,并引入经验成分来校准模型。本文采用第二种方法。利用膨胀角,塑性应变率,有效变形模量,有效泊松比,格里菲斯轨迹以及Kaiser等人提出的 BF italic>定义,建立了半经验岩体膨胀模型。 。 (1996)。为了根据实验数据获得 BF italic> s,对模型进行了校准,并通过案例研究来说明地下基坑周围的体积。 (摘要由UMI缩短。)
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