结构面间距是表征岩体完整性的重要参数。由于结构面分布的不均匀性和地质构造的复杂性,常用的概率分布不能精细描述结构面间距的分布特征。对于由测线法测得的结构面间距样本,根据岩体内部能量平衡,在结构面间距的统计矩的约束下,采用最大熵原理推导结构面间距的概率分布,最大熵原理估计得到的结构面间距的概率分布具有无偏性和一致性;给出结构面间距常用的分布函数的最大熵形式;采用Monte Carlo模拟方法进行结构面三维网络模拟,采用K-S检验验证最大熵估计结构面间距概率分布的适用性和准确性。对隧道采样区的结构面间距样本进行分布估计,得到的最大熵概率分布显著优于常用的负指数分布或对数正态分布,能够准确反映结构面间距的真实分布情况。
The discontinuity spacing is an important parameter to characterize the integrality of rock mass. Due to the complexity of the geological processes leading to the development of rock discontinuities, exponential and lognormal distributions can not adequately describe the discontinuity spacing in the field. With the discontinuity spacing data, the maximum entropy principle is applied by an energy balance to derive the discontinuity spacing distribution, and the obtained maximum entropy distribution is unbiased and consistent. A three dimensional discontinuity network is generated by Monte Carlo simulation. The discontinuity spacings are calculated along 5 different scanlines. The maximum entropy distribution and exponential distribution are used to estimate the discontinuity spacing distributions. Then, K-S tests are used to test the goodness-of-fit to the spacings. The sampling data of discontinuity spacing from Maluanshan tunnel are analysed and estimated by the proposed method. The results show that the maximum entropy distribution exhibits the better performance compared to exponential and lognormal distributions.