Numerical Investigation of a Hydrosplitting Fracture and Weak Plane Interaction Using Discrete Element Modeling

Shuaiqi Liu,Jie Guo,Qihao Sun,Fengshan Ma,Haijun Zhao,Xueliang Duan

doi:10.3390/w12020535

Abstract

Water inrush caused by hydrosplitting is an extremely common disaster in the engineering of underground tunnels. In this study, the propagation of fluid-driven fractures based on an improved discrete element fluid-solid coupling method was modeled. First, the interactions between hydrosplitting fractures (HFs) and preexisting weak planes (WPs) with different angles were simulated considering water pressure in the initial fracture. Second, the influence of the in situ stress ratio and the property of WPs were analyzed, and corresponding critical pressure values of different interactions were calculated. Lastly, the maximum principal stress and maximum shear stress variation inside the pieces were reproduced. The following conclusions can be drawn: (1) Five different types of interaction modes between HFs and natural WPs were obtained, prone to crossing the WPs under inclination of 90°. (2) The initiation pressure value decreased with an increased in situ stress ratio, and the confining stress status had an effect on the internal principal stress. (3) During HFs stretching in WPs with a high elastic modulus, the value of the maximum principal stress was low and rose slowly, and the maximum shear stress value was smaller. Through comprehensive analysis, the diversity of the principal stress curves is fundamentally determined by the interaction mode between HFs and WPs, which are influenced by the variants mentioned in the paper. The analysis provides a better guideline for understanding the failure mechanism of water gushing out of deep buried tunnel construction and cracking seepage of high head tunnels.

Highlights

Water inrush in deep chambers is a major problem that threatens the safe production of coastal mines
The diversity of the principal stress curves is fundamentally determined by the interaction mode between hydrosplitting fractures (HFs) and weak planes (WPs), which are influenced by the variants mentioned in the paper
Natural fractures (NFs), new as as well as the networks formed by the of HFs, NFs, new fractures fracturesdriven drivenby bywater waterpressure, pressure, well as the networks formed by interaction the interaction of HFs, and

Summary

Introduction

Water inrush in deep chambers is a major problem that threatens the safe production of coastal mines. Mines have been drilled to a depth of several thousand meters [1], and the action of high in situ stress and high osmotic pressure makes water inrush disasters more frequent. Hydrosplitting is a general term for physical phenomena such as crack initiation and propagation and interpenetration of existing cracks in rock mass under the action of high-pressure flow [2]. Mine water inrush, leaking during the construction of deep buried tunnels, and cracking of high-pressure water conveyance tunnels are typical examples of hydrosplitting [3,4,5]. Water 2020, 12, 535 is of important theoretical and practical significance for seepage analysis and safe production in underground engineering.

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Results

Conclusion