基于分形理论的结构面迹长分布模式及连通率影响因素分析

Analysis of Influencing Factors on Distribution Pattern of Joint Trace Length and Joint Connectivity Rate Based on Fractal Theory

对结构面迹长的描述与估计对计算结构面连通率至关重要。目前,描述基体裂隙迹长的方法通常偏重于平均迹长的估计,难以精确描述结构面迹长的空间发育状况。基于分形理论,利用分形维D描述了结构面迹长分布模式。如果结合结构面迹长区间、优势迹长区间及其内裂隙发育的相对数量I(%),即可详细描述基体裂隙迹长的空间发育状况。以西南某大型水电站工程坝区建基面的基岩裂隙为例,对分形维D和裂隙发育的相对数量I(%)进行分类和组合,总结出结构面迹长发育的3种模式:M1、M2和M3,并探讨了各种迹长发育模式下,连通率k的影响控制因素。结果发现,当裂隙迹长的发育模式为M1和M2时,结构面的空间分布状况对连通率k的影响较大;当裂隙迹长的发育模式为M3时,连通率k主要与裂隙迹长的平均值L0有关,相应裂隙空间分布对k的影响较小。

An accurate description and estimation of the joint trace length is important to the calculation of joint connectivity rate. At present, the commonly used method to describe the trace length focuses on the estimation of average trace length, which cannot characterize precisely the spatial distribution of joint trace length. Based on the fractal theory, fractal dimension D is used to describe the distribution pattern of joint trace. The combination of the joint trace length interval, primary trace length inter- val, and the percentage of joint development I （%） in the primary trace length interval can provide detailed spatial distribution of joint trace length. In this paper, the joints in the rock mass of dam foundation of a large hydropower station in the southwest of China are studied. The values of D and I are analyzed and classified, and three forms （M1, M2, and M3） of development of joint trace length are summarized. The influencing factors on the joint connectivity rate k are discussed for each form of devel- opment of joint trace length. The results show that the spatial distribution of joint has significant effects on the joint connectivi-ty rate k under the forms M1 and M2, while the joint connectivity rate k is more related to the average joint trace length Lo than the spatial distribution of joint under the form M3.