Numerical Simulation on Zonal Disintegration in Deep Surrounding Rock Mass

Xuguang Chen,Xin Zhang,Yuan Wang,Yu Mei

doi:10.1155/2014/379326

Xuguang Chen, Xin Zhang + Show 2 more

Open Access

https://doi.org/10.1155/2014/379326

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Abstract

Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks.

Highlights

Many countries have begun to focus on deep resource exploitation
With an increase in embedded depth, the zonal disintegration phenomenon occurs during tunnel excavation
Zonal disintegration poses a great danger during the excavation of deep tunnels [7]

Summary

Introduction

With an increase in embedded depth, the zonal disintegration phenomenon occurs during tunnel excavation. Zonal disintegration refers to “alternating regions of fractured and relatively intact rock masses appearing around or in front of the working stope during the excavation of tunnels in the deep rock mass” [1]. It is a special geological phenomenon that is different from what is observed for shallow embedded tunnels and presents a great hazard to the stability of deep surrounding rocks [2]. Zonal disintegration poses a great danger during the excavation of deep tunnels [7]. It is a character of the deep rock mass and has recently been a subject of focus. Some specialists have used nonequilibrium thermodynamics (Metlov L S, 2002), Hamilton time domain variation (LI SC, 2009), or a non-Euclidean model (GUZEV M A, 2001) to study the forming mechanism

Materials and Methods

Conclusions