Purpose

This research study aims to develop regular cylindrical pore network models (RCPNMs) to calculate topology and geometry properties of explosively created fractures along with their resulting hydraulic permeability. The focus of the investigation is to define a method that generates a valid geometric and topologic representation from a computational modelling point of view for explosion-generated fractures in rocks. In particular, extraction of geometries from experimentally validated Eulerian smoothed particle hydrodynamics (ESPH) approach, to avoid restrictions for image-based computational methods.

Design/methodology/approach

Three-dimensional stabilized ESPH solution is required to model explosively created fracture networks, and the accuracy of developed ESPH is qualitatively and quantitatively examined against experimental observations for both peak detonation pressures and crack density estimations. SPH simulation domain is segmented to void and solid spaces using a graphical user interface, and the void space of blasted rocks is represented by a regular lattice of spherical pores connected by cylindrical throats. Results produced by the RCPNMs are compared to three pore network extraction algorithms. Thereby, once the accuracy of RCPNMs is confirmed, the absolute permeability of fracture networks is calculated.

Findings

The results obtained with RCPNMs method were compared with three pore network extraction algorithms and computational fluid dynamics method, achieving a more computational efficiency regarding to CPU cost and a better geometry and topology relationship identification, in all the cases studied. Furthermore, a reliable topology data that does not have image-based pore network limitations, and the effect of topological disorder on the computed absolute permeability is minor. However, further research is necessary to improve the interpretation of real pore systems for explosively created fracture networks.

Practical implications

Although only laboratory cylindrical rock specimens were tested in the computational examples, the developed approaches are applicable for field scale and complex pore network grids with arbitrary shapes.

Originality/value

It is often desirable to develop an integrated computational method for hydraulic conductivity of explosively created fracture networks which segmentation of fracture networks is not restricted to X-ray images, particularly when topologic and geometric modellings are the crucial parts. This research study provides insight to the reliable computational methods and pore network extraction algorithm selection processes, as well as defining a practical framework for generating reliable topological and geometrical data in a Eulerian SPH setting.

中文翻译：

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通过规则圆柱形孔隙网络模型估计爆炸性裂缝的拓扑和水力渗透率

目的

本研究旨在开发规则圆柱形孔隙网络模型 (RCPNM)，以计算爆炸产生的裂缝的拓扑和几何特性及其产生的水力渗透率。研究的重点是定义一种方法，从计算建模的角度为岩石中爆炸产生的裂缝生成有效的几何和拓扑表示。特别是，从经过实验验证的欧拉平滑粒子流体动力学 (ESPH) 方法中提取几何图形，以避免对基于图像的计算方法的限制。

设计/方法/方法

需要三维稳定的 ESPH 解决方案来模拟爆炸产生的裂缝网络，并且根据峰值爆轰压力和裂纹密度估计的实验观察，定性和定量地检查开发的 ESPH 的准确性。使用图形用户界面将 SPH 模拟域分割为空隙和实体空间，爆破岩石的空隙空间由由圆柱形喉道连接的球形孔隙的规则格子表示。将 RCPNM 产生的结果与三种孔隙网络提取算法进行比较。因此，一旦确认 RCPNM 的准确性，就可以计算裂缝网络的绝对渗透率。

发现

将 RCPNMs 方法获得的结果与三种孔隙网络提取算法和计算流体动力学方法进行比较，在所有研究的情况下，在 CPU 成本方面实现了更高的计算效率以及更好的几何和拓扑关系识别。此外，可靠的拓扑数据没有基于图像的孔隙网络限制，拓扑无序对计算的绝对渗透率的影响很小。然而，需要进一步研究以改进对爆炸产生的裂缝网络的真实孔隙系统的解释。

实际影响

尽管在计算示例中仅测试了实验室圆柱形岩石标本，但所开发的方法适用于具有任意形状的现场尺度和复杂孔隙网络网格。

原创性/价值

通常需要开发一种用于爆炸产生的裂缝网络的水力传导率的集成计算方法，其中裂缝网络的分割不限于 X 射线图像，特别是当拓扑和几何建模是关键部分时。这项研究为可靠的计算方法和孔隙网络提取算法选择过程提供了见解，并定义了在欧拉 SPH 设置中生成可靠拓扑和几何数据的实用框架。