基于图像数字化技术的裂隙岩体非稳态渗流分析

ANALYSIS OF TRANSIENT FLUID FLOW IN FRACTURED ROCK MASSES WITH DIGITAL IMAGE-BASED METHOD

对于岩体的非均质性和微结构分布,多引用统计学随机抽样方法来描述。引入图像数字化技术来真实客观地反映岩体的主干裂隙、次裂隙及裂隙化区域和较完整岩块的分布,并将其和数值方法相结合,用来分析二维裂隙岩体的非稳定渗流过程。首先,需要获得高清晰度的岩体数字图像及岩体中不同结构对应的不同特征值I,这样通过I值可建立起岩体中不同结构渗透系数的真实分布。其次,将该物理参数分布输入到开发的基于FEMLAB的岩体多物理耦合过程分析程序中,就可真实地反映裂隙岩体的非稳定渗流过程。数值分析结果表明,该方法是可行且有效的,比统计抽样方法有明显的优点,其结果更能反映真实的物理现象。

The realistic characterization of rock heterogeneity has been a long-standing problem of great practical interest. The heterogeneity of the fractured rock masses can be described by statistical random sampling in most numerical simulations. In this study, a digital image based（DIB） numerical method is proposed for the two-dimensional transient seepage analysis of the fractured rock masses by actually taking the spatial distribution of main fractures, minor fractures and intact rock into account. The digital image processing technique is developed to identify and classify the main structures（i.e, fractures, intact rocks） in the fractured rock masses and their intrinsic permeabilities are specified to these main structures. Then the characterized permeabilities of these structures are directly imported into newly developed three-dimensional simulator SCMR, a FEMLAB-based simulator of coupled multiphysics in rocks, to evaluate the effect of heterogeneity on the transient fluid flow in the fractured rock masses. The digital image based numerical results of transient fluid flow show that the digital image-based technique is capable to characterize the heterogeneity and the fracture structures of fractured rock masses. The digital image based technique is more advantageous than the statistical method in characterizing the rock heterogeneity and provides a new approach to obtain the realistic results.