《International Journal of Geomechanics》杂志刊登“大坝坝基剪切带的特征与其离散元模型”

作  者：Alessandro Graziani, Claudio Rossini, Tatiana Rotonda

刊  物：《International Journal of Geomechanics》，12卷第6期，617-734页

摘  要：从类土壤材料过渡到硬质岩体，碎裂岩和断层泥呈现高度可变的特性。多数情况下，整个岩体或内部主要的剪切带可以用块矩阵岩表示，即不同形状和大小的岩石片段可以用更精细的矩阵来表示。本文调查了一座正在设计规划中的其坝基为经历过构造运动的变质岩体的重力坝。坝基有大量不连续带，这些不连续带具有韧性好、波纹状和丰富的碎裂物质填充的特性，可组成很宽的剪切带。局部方向的系统量测与沿不连续带的夹层厚度使得可以对其进行详细形态分析。最常见的填充类型是可以用矩阵表示的轻胶结泥。只有在一些特殊的情况下，才可取得填充材料的原状样。因此，室内试验和现场原位测试难度较大且很难做到全面测量。细观的离散元模型有助于得到碎裂材料较全面的变形和破坏机理。颗粒状模型的机械性能首先是通过双轴和直剪试验的数值模拟得到的。同时也确定了整体的本构参数和微观性能如颗粒间的摩擦、接触刚度、水泥粘结强度、体积块比例、块的形状之间的关系。并调查了主要不连续体的几何特性（接触面的粗糙度和波纹度）和填充的块矩阵岩的特性之间复杂的相互作用，最后分析了具有填充不连续体的整体强度。

Characterization and DEM Modeling of Shear Zones at a Large Dam Foundation

Authors: Alessandro Graziani, Claudio Rossini, Tatiana Rotonda

Journal: International Journal of Geomechanics, Volume 12, Issue 6(2012), 617-734

Abstract: Cataclastic rocks and fault gouge present highly variable properties, from those of soil-like materials to those of competent rock mass. In most cases, the entire rock mass, or internal major shear zones, can be represented as a block-in-matrix rock (bimrock), i.e., rock fragments of different shape and size, embedded in a finer matrix. In this paper, a tectonized metamorphic rock mass at the site of a planned gravity dam is investigated. The dam foundation is crossed by numerous major discontinuities, often grouped to form wider shear zones and characterized by high persistency, waviness, and abundant cataclastic filling. Systematic measurements of local orientation and filling thickness along the discontinuity traces made a detailed morphological analysis possible. The most frequent type of filling is a lightly cemented matrix-supported gouge. Undisturbed sampling of filling materials was successful only in some special cases. Laboratory tests, as well as in-situ mechanical tests, were therefore difficult and not exhaustive. Micromechanical distinct-element method (DEM) modeling was instrumental in obtaining a more comprehensive framework of deformation and failure mechanisms of cataclastic materials. The mechanical properties of the particulate model were first analyzed by numerical simulation of biaxial and direct shear tests. The relationship between the overall constitutive parameters and micromechanical properties, such as interparticle friction, contact stiffness, cement bond strength, volumetric block proportion, and block shape, was determined. The complex interplay between the geometric features of a major discontinuity (joint-wall roughness and waviness) and the properties of the infilling bimrock was then investigated, and finally, the overall strength of the infilled discontinuity was analyzed.
原文链接：http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GM.1943-5622.0000220

翻译：翟洁；审核：安鹏