scholarly journals Research on Failure Mechanism and Parameter Sensitivity of Zonal Disintegration in Deep Tunnel

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Xutao Zhang ◽  
Qiang Gao ◽  
Shicai Cui ◽  
Changrui Duan
Keyword(s):  
Rock Mass ◽  
Failure Mechanism ◽  
Deformation Modulus ◽  
Morphological Characteristics ◽  
Zonal Disintegration ◽  
Deep Tunnel ◽  
Equilibrium Equations ◽  
Distribution Law ◽  
Deep Rock Mass ◽  
Deep Rock

With the increase of excavation depth, the zonal disintegration phenomenon appears in the deep rock mass, which is quite different from the failure mode of shallow tunnel. In order to analyse the failure mechanism of this phenomenon, an elastoplastic softening damage model was put forward based on the softening damage characteristics of deep rock mass. The constitutive equations, the equilibrium equations, and the failure criterion were deduced. The theoretical solutions of radial displacement and radial stresses and tangential stresses of deep surrounding rock mass were calculated. The distribution law of zonal disintegration in deep tunnel was obtained. The theoretical solutions presented an oscillating mode. The theoretical calculated widths of fracture zones were in good agreement with the in situ test data. Besides, the sensitivity of different parameters to fracture morphology was calculated and analysed. The results show that the relative loading strength has a controlling role in the zonal disintegration morphology, followed by the cohesion force and deformation modulus, and the internal friction angle is the least. This study reveals the morphological characteristics and influencing factors of zonal disintegration, which provides a basis for the prediction and support control of fracture modes.

Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three-Dimensional Bonded Block Model

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Qingteng Tang ◽  
Wenbing Xie ◽  
Xingkai Wang ◽  
Zhili Su ◽  
Jinhai Xu
Keyword(s):  
Rock Mass ◽  
Fracture Zone ◽  
Numerical Study ◽  
Confining Pressure ◽  
Surrounding Rock ◽  
Zonal Disintegration ◽  
Block Model ◽  
Deep Rock Mass ◽  
Damaged Zone ◽  
Deep Rock

Zonal disintegration, a phenomenon of fractured zones and intact zones distributed alternately in deep rock mass, is different from the excavation-damaged zone of shallow rock mass. In this study, bonded block model of 3DEC was employed to study the fracture mode and origination condition of zonal disintegration. Initiation, propagation, and coalescence progress of fracture around the roadway boundary under different triaxial stress conditions are elaborated. Numerical simulation demonstrated that zonal disintegration may occur when the direction of maximum principal stress is parallel to the roadway axis. It is interesting to find that the fracture around the roadway boundary traced the line of a spiral line, while slip-line fractures distributed apart from the roadway boundary. The extent of the alternate fracture zone decreased as the confining pressure increased, and alternate fracture zone was no longer in existence when the confining pressure reaches a certain value. Effects of roadway shape on zonal disintegration were also studied, and the results indicated that the curvature of the fracture track line tends to be equal to the roadway boundary in shallow surrounding rock of the roadway, while the fractures in deep surrounding rock seems unaffected by the roadway shape. Those findings are of great significance to support design of deep underground openings.

Microseism Induced by Transient Release of In Situ Stress During Deep Rock Mass Excavation by Blasting

2012 ◽  
Vol 46 (4) ◽  
pp. 859-875 ◽  
Author(s):  
Jianhua Yang ◽  
Wenbo Lu ◽  
Ming Chen ◽  
Peng Yan ◽  
Chuangbing Zhou
Keyword(s):  
Rock Mass ◽  
In Situ Stress ◽  
Deep Rock Mass ◽  
Deep Rock

scholarly journals Study on the Generation Mechanism and Development Law of the Zonal Disintegration in Deep Burial Tunnels

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Xiaohui Ma ◽  
Jihong Wei ◽  
Jin Liu ◽  
Zezhuo Song ◽  
Yuxia Bai
Keyword(s):  
Mechanical Properties ◽  
Rock Mass ◽  
Maximum Stress ◽  
Axial Stress ◽  
Axial Direction ◽  
Tensile Failure ◽  
Zonal Disintegration ◽  
Nonlinear Characteristics ◽  
Deep Rock ◽  
New Phenomena

In the development of underground spaces, we found that the mechanical properties of rock mass often demonstrate strong nonlinear characteristics. Some new phenomena emerge in deep rock mass engineering. This includes zonal disintegration and rock burst. Zonal disintegration is very important in deep tunnels. In this paper, we start with the mechanical properties of deep rocks to understand the preconditions for zonal disintegration. Using the Failure Approach Index (FAI), the process of zonal disintegration can be modeled by FLAC (FISH language). Our results indicate that tensile failure in the Supporting Pressure Zone (SPZ) is a precondition for zonal disintegration. Various factors that affect the generation of zonal disintegration are studied. When the maximum stress is in the axial direction, zonal disintegration will be present in deep tunnels. The high axial stress is necessary for zonal disintegration. We will present a zonal disintegration simulation in one coal mine for comparison with the borehole teleview data. We suggest some measures to prevent the development of zonal disintegration.

Study on Center Hole Deformation Test of Rigid Bearing Plate

2008 ◽  
Vol 33-37 ◽  
pp. 1187-1194
Author(s):  
Jian Guo Zhang ◽  
Qiang Yong Zhang ◽  
Wen Dong Yang ◽  
Ying Zhang
Keyword(s):  
Rock Mass ◽  
Deformation Modulus ◽  
Hydropower Station ◽  
Weak Rock ◽  
Bearing Plate ◽  
Deep Rock ◽  
Weak Rock Mass ◽  
Deformation Test ◽  
Test Points ◽  
Dagangshan Hydropower Station

The center hole deformation test of rigid bearing plate is an important method for understanding deformation properties of deep weak rock mass. According to the center hole deformation test of rigid bearing plate in dam zone of Dagangshan hydropower station, this paper detailedly recommends test method of this experiment, and the settlement deformation formula of deep rock mass under circular rigid bearing plate is deduced, which could be used to calculate deformation modulus and equivalence deformation modulus of different deep rock mass at test points. According to curves of depth-deformation under different pressures at test points in dam zone, we have analyzed deformation characteristics of deep weak rock mass. By the center hole deformation test of rigid bearing plate, stratum properties in dam zone of Dagangshan hydropower station could be understood further, and it provides important references for the study of creep speciality of weak rock mass in dam zone.

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