Numerical investigation on permeability evolution behavior of rock by an improved flow-coupling algorithm in particle flow code

来源期刊:中南大学学报(英文版)2018年第6期

论文作者:杨圣奇 曾卫 田文岭 文凯

文章页码:1367 - 1385

Key words:rock mechanics; fluid-solid coupling; particle flow code (PFC); permeability; triaxial compression

Abstract: Permeability is a vital property of rock mass, which is highly affected by tectonic stress and human engineering activities. A comprehensive monitoring of pore pressure and flow rate distributions inside the rock mass is very important to elucidate the permeability evolution mechanisms, which is difficult to realize in laboratory, but easy to be achieved in numerical simulations. Therefore, the particle flow code (PFC), a discrete element method, is used to simulate permeability behaviors of rock materials in this study. Owe to the limitation of the existed solid-fluid coupling algorithm in PFC, an improved flow-coupling algorithm is presented to better reflect the preferential flow in rock fractures. The comparative analysis is conducted between original and improved algorithm when simulating rock permeability evolution during triaxial compression, showing that the improved algorithm can better describe the experimental phenomenon. Furthermore, the evolution of pore pressure and flow rate distribution during the flow process are analyzed by using the improved algorithm. It is concluded that during the steady flow process in the fractured specimen, the pore pressure and flow rate both prefer transmitting through the fractures rather than rock matrix. Based on the results, fractures are divided into the following three types: I) fractures link to both the inlet and outlet, II) fractures only link to the inlet, and III) fractures only link to the outlet. The type I fracture is always the preferential propagating path for both the pore pressure and flow rate. For type II fractures, the pore pressure increases and then becomes steady. However, the flow rate increases first and begins to decrease after the flow reaches the stop end of the fracture and finally vanishes. There is no obvious pore pressure or flow rate concentration within type III fractures.

Cite this article as: ZENG Wei, YANG Sheng-qi, TIAN Wen-ling, WEN Kai. Numerical investigation on permeability evolution behavior of rock by an improved flow-coupling algorithm in particle flow code [J]. Journal of Central South University, 2018, 25(6): 1367–1385. DOI: https://doi.org/10.1007/s11771-018-3833-5.

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