Experimental study on seepage characteristics of microfracture with different aperture

Shuai Zhang,Yue Wu,Zhenwang Fan,Lei Zhang,Weiguo Qiao

doi:10.1038/s41598-020-62350-y

Shuai Zhang, Yue Wu + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-62350-y

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Abstract

Exploring the flow mechanism of fluid in rock mass is important in solving the water inrush problems during tunnel excavation. However, it is difficult to obtain an undisturbed rock mass from the actual site conditions and study the flow mechanism of fluid through a fracture network composed of multiple single fractures. Therefore, a solution to simulate rock seepage using rock-like samples with single microfracture was presented in this paper. Water flow through microfracture was tested and the deformation of microfracture was recorded by quasi-distributed fiber Bragg grating (FBG) technology. Experimental data showed that Forchheimer’s law and Izbash’s law could well describe the nonlinear relationship between flow velocity and hydraulic gradient. The coefficient b in Forchheimer’s equation decreased with the increase of microfracture aperture. A critical value of E = 0.8 was proposed to classify the nonlinear flow regime: weak turbulence (E < 0.8) and fully developed turbulence (E > 0.8).

Highlights

Exploring the flow mechanism of fluid in rock mass is important in solving the water inrush problems during tunnel excavation
Investigation on seepage characteristics of rock mass plays an essential role in solving the problem of water inrush during the construction and development of underground engineering, for example geothermal excavation, construction of dam foundations, oil or shale gas exploitation, storage of nuclear waste, contaminant pollution control, groundwater utilization and grouting engineering[1,2,3]
Zhang et al.[13] designed a physical model of fractured rock mass with different fracture aperture for seepage test and found that the flow velocity decreases with increasing fracture aperture under stable hydraulic pressure difference

Summary

Introduction

Exploring the flow mechanism of fluid in rock mass is important in solving the water inrush problems during tunnel excavation. In order to reveal the seepage mechanism of rock mass, it is necessary to study the flow characteristics of a single fracture. The main objective is to simulate the microfracture seepage with different aperture under incremental change in normal and hydraulic pressures applying to samples.

Results

Conclusion