岩体尺寸效应及其特征参数计算

 岩体的尺寸效应包括完整岩块的尺寸效应与节理岩体的尺寸效应，但两者之间还缺乏有机联系。基于物理力学试验与细观参数统计分布理论，建立试样尺度的随机概率模型。通过统计宏观节理分布，建立包含随机分布节理的岩体尺度模型。将实验室获得的岩块强度应用于岩体的计算中，提出一种从细观层次、宏观层次的多尺度岩体工程计算方法，建立2种尺度效应的联系。最后，就非均匀性、围压与节理密度对岩石尺寸效应的影响问题展开探讨。随着均值度的增加，试样的特征尺度逐渐减小。随着围压的增大，岩体特征强度逐渐增大，而岩体力学参数的特征尺寸增大不明显。随着节理密度的增大，特征尺寸和相应的特征强度都是减小的。本方法试图建立细观与宏观力学参数之间的桥梁，获得岩体计算的力学参数，为解决工程岩体参数取值与计算提供一条思路。

SIZE EFFECT OF ROCK MESSES AND ASSOCIATED REPRESENTATIVE ELEMENT PROPERTIES

The rock size effect，including intact rock size effect and size effect of jointed rock mass，is a hot topic in rock mechanics and rock engineering. However，determining the parameters of intact rocks and the rock mass with randomly distributed joints is much difficult in numerical simulations. In this paper，it is assumed that the rock mass is composed of intact rock with joints. Based on physico-mechanical test and microscopic parameter statistical theory，a statistical model is built to study the intact rock scale effect. Based on the statistical analysis of macro joint distribution，a macroscopic rock mass model is put forward to investigate the rock mass scale effect. The main idea is described as follows：(1) A statistical model can be established by analyzing the data of the laboratory experimental tests of intact rocks. The representative element size and its strength can be obtained by studying the scale effect of the intact rocks. (2) By determining the mechanical parameters of the joints and the geometric distribution parameter of the joints，the numerical network model of joints can be established. (3) The rock mass model with different scales can be built to study the rock mass scale effect，and then，the representative element size and its strength can be calculated. By using the strength reduction FEM or centrifugal loading method，the stability of the rock engineering can be analyzed according to the mechanical parameters of the jointed rock mass. Finally，the influences of the heterogeneity，confining pressure and density of joints on rock size effect are discussed. With increase of heterogeneity，representative element volume of rock sample increases；with increase of confining pressure，the representative strength increases but the increase of representative element volume is not obvious；with increase of density of joints，the representative element volume and strength decrease. The results will be useful for understanding the rock mass scale effect and provide a helpful way to obtain the mechanical parameters of jointed rock mass.