On the description of fracture and dilatancy in granite by modeling acoustic emission signal-cloud

Dongjie Xue • Lan Lu • Lie Gao • Lele Lu • Cheng Chen

Abstract: The invisibility of fracture network evolution in the rock under triaxial compression seriously restricts the correlation modelling between dilatancy behavior and fracture interconnectivity. The key to solving such a challenge is very dependent on the accurate modelling of the spatial correlation in fracture network, which could be indirectly re-constructed by the signal cloud of acoustic emission (AE). Considering the interaction of local fractures, a cube-clustering approach is established to describe the spatial correlation. The evolutional cube clusters effectively present the geometric characteristics induced by the increasing dilatancy of fracture. Two descriptors of three-axis length sum and pore fraction are introduced to build the correlation of cluster model and dilatancy behavior. Most fitting results support the linear correlation between two descriptors and volumetric strain, which verifies the sensitiveness of the cube cluster model on dilatancy. More importantly, by the statistical analysis of cluster structure, the cluster model shows the potential of calculating fracture angle. Moreover, a comparison between dilatancy-based damage and porosity-based damage is made not to proving the best but providing an AE-based prediction of local damage evolution. Finally, four classical models of calculating fracture angle are compared. The deviations prove the huge difficulty of describing the development of the fracture network uniquely dependent on a fracture angle. The proximity of measured angle and cluster-based angle supports the effectiveness of predication by the cube-clustering approach.

Keywords: Fracture network; Acoustic emission; Spatial correlation; Dilatancy; Damage; Fracture angle

引用格式：

Xue Dongjie, et al. On the description of fracture and dilatancy in granite by modeling acoustic emission signal-cloud, Journal of Rock Mechanics and Geotechnical Engineering [J]，2021.

DOI

全文链接：https://www.sciencedirect.com/science/article/pii/S1674775521000822

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本文亮点（或创新点）

1. 建立团簇模型实现了基于声发射云团描述岩石剪胀行为

2. 建立团簇模型提供了一种基于声发射云团描述岩石损伤空间分布演化的新方法

3. 建立团簇模型提供了一种基于声发射云团计算破裂角演化的新方法

为基于声音信号模拟甚至预测岩石破裂力学行为打开了一扇窗口！

部分图表（高清图片）

图1 空间关联性一一映射问题来源

图2 一一映射基本原理

图3 团簇模型计算损伤演化

图4 团簇模型计算破裂角