Open Access

ARTICLE

Experimental Study on Seepage Characteristics of a Soil-Rock Mixture in a Fault Zone

Pengfei Wang^1,2, Xiangyang Zhang^1,*
1Key Laboratory of Safety and High-Efficiency Coal Mining, Ministry of Education, Anhui University of Science and Technology, Huainan, 232001, China
2School of Architecture and Civil Engineering, Huangshan University, Huangshan, 245041, China
* Corresponding Author: Xiangyang Zhang. Email:
(This article belongs to this Special Issue: EFD and Heat Transfer III)

Fluid Dynamics & Materials Processing 2022, 18(2), 271-283. https://doi.org/10.32604/fdmp.2022.017882

Received 14 June 2021; Accepted 12 August 2021; Issue published 16 December 2021

Abstract

A mixture of fault gouge and rubble taken out from a fault zone is used to prepare a S-RM (Soil-Rock Mixture) sample with rock block proportions of 20%, 30%, 40%, 50%, 60% and 70%, respectively. A GDS triaxial test system is used accordingly to measure the seepage characteristics of such samples under different loading and unloading confining pressures in order to determine the variation law of the permeability coefficient. The test results show that: (1) The permeability coefficient of the S-RM samples decreases as the pressure increases, and the decrease rate of this coefficient in the initial stage of confining pressure loading is obviously higher than in the semi-late period; (2) The permeability coefficient at different confining pressure levels presents a common trend as the rock block proportion is increased, i.e., it decreases first then it increases (the permeability coefficient of the sample with rock block proportion 40% being the smallest, 70% the largest); (3) In the stage of confining pressure unloading, the recovery degree of the permeability coefficient grows with the increase of rock block proportion (the recovery rate of S-RM sample with rock block proportion 70% reaches 50.2%); (4) In the stage of confining pressure loading and unloading, the sensitivity of the permeability coefficient to the rock block proportion displays the inverse “Z” variation rule (when rock block proportion reaches 60%, the sensitivity is highest); (5) In the stage of confining pressure loading, the relationship between the permeability coefficient and confining pressure can be described by an exponential relationship.

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Keywords

Fault zone; rock block proportion; soil-rock mixture; confining pressure loading and unloading; seepage characteristic

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