自然科学版 英文版
自然科学版 英文版
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中南大学学报(英文版)

Journal of Central South University

Vol. 25    No. 6    June 2018

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Numerical investigation on permeability evolution behavior of rock by an improved flow-coupling algorithm in particle flow code
ZENG Wei(曾卫)1, YANG Sheng-qi(杨圣奇)1, TIAN Wen-ling(田文岭)1, WEN Kai(文凯)2

1. State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China; 2. Laboratory of Rock Engineering and Mining Machinery, Kyushu University, Fukuoka 819-0395, Japan

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.

 

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

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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