基于块体化程度统计的裂隙岩体表征单元体研究

Representative elementary volume (REV) is an essential concept in the study of fractured rock mass. The existence of REV is the premise of continuum methods in rock mechanics for rock mass. However, determining the existence and size of REV is still a difficult scientific problem because of the complexity of fractured rock masses. This study presents an analysis of the REV from the view of blockiness , which is used to measure rock’s level of being an assemblage of isolated blocks. Frist, a variety of 3D rock mass fracture network models (including "the theoretical rock masses", published fracture network models which were published by various authors and the some actual rock masses) are built using the self-developed software. Rock blocks in each of these fracture network models are identified and the fluctuation in blockiness with the variation in the scale of the model region is also investigated. In this way, the blockiness of these fractured rock masses can be determined statistically and the size of the REV in these models can be calculated as indicators of the convergence. In this study, parallel algorithm is added into the block identification calculation, which improves the efficiency of the processing. This research provides a new idea for determining the existence of REV in rock masses and a scientific basis for revealing the essential characteristics of rock masses structure.

表征单元体是岩体力学中的基础性概念，对岩体来说，表征单元体（REV）的存在是应用连续介质力学方法对其进行研究的前提。然而由于实际岩体裂隙结构异常复杂，REV的存在和大小至今是一个难以解决的科学问题。本研究从块体化程度的角度研究REV的存在性及其大小，利用块体化程度定量描述裂隙岩体在多大程度上可以被看作“块体的集合体”。研究采用自主研发的软件，建立岩体3D裂隙网络模型（包括“理论岩体”、不同作者发表的裂隙模型和三峡工程坝区等实际岩体），识别岩体中所有块体及其几何参数，绘制块体化程度与模型范围的关系图，采用统计学原理，分析各裂隙岩体的块体化程度，判断结果的收敛性，进而确定各类岩体REV的存在性及其大小。本研究把并行算法加入到块体识别计算机方法，提高块体计算效率，为判定岩体REV是否存在提供新思路，为揭示实际岩体结构本质特征提供科学依据。

表征单元体（REV）是岩体力学中的基础性概念，它的存在是应用连续介质方法研究岩体问题的前提。表征单元体的存在与否可以从不同物理参数的角度进行分析，本研究从块体化程度的角度研究REV的存在性及其大小。根据国际岩石力学学会的裂隙分级，建立了77种岩体结构模型。采用自主研发的块体分析软件GeneralBlock，对这77种岩体进行了块体识别，讨论了这77种岩体结构的块体化程度随着模型范围变化的波动情况。由于所建立的岩体结构模型是随机的，对每种结构的每个研究范围进行了99次随机实现。并采用变异系数判断结果的收敛性，进而确定各类岩体REV的存在性及其大小。结果表明，对所有的77种岩体，其中76种裂隙岩体的表征单元体尺寸在2-20倍裂隙间距之间；宽间距-非常高延展性的裂隙岩体模型的表征单元体存在，尺寸大于20倍裂隙间距。本研究为判定岩体REV是否存在提供新思路，为揭示实际岩体结构本质特征提供科学依据。