scholarly journals Zonal Disintegration Mechanism of Deep Rock Masses under Coupled High Axial Geostress and Blasting Load

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Pu Yuan ◽  
Ying Xu
Keyword(s):  
Stress Field ◽  
Numerical Computation ◽  
Elastic Stress ◽  
Damage Effect ◽  
Zonal Disintegration ◽  
Deep Tunnel ◽  
Rock Masses ◽  
Fracture Zones ◽  
Deep Rock ◽  
Blasting Load

Zonal disintegration phenomenon with alternative distribution of fracture zones and nonfracture zones is a characteristic failure in deep rock masses, especially for deep tunnel excavated by drill and blast method. To investigate the mechanism of zonal disintegration under coupled high axial geostress and blasting load, elastic stress field distribution for a circular tunnel in deep isotropic rock masses is obtained. Furthermore, Hoek-Brown criterion is amended by considering blast-induced damage effect. Both radial blasting load and blast-induced damage effect are assumed to decay in a negative exponential function. Taking the deep tunnel of Dingji coal mine in China as engineering background, the number and width of fracture zones are determined by deduced elastic stress field and modified Hoek-Brown criterion. Then numerical computation is conducted. Numerical computation results indicate that both the number and width of fracture zones mainly depend on high axial geostress and mechanical parameters of deep rock masses, and peak radial blasting load plays an important role in determining the width of fracture zone near the excavation.

scholarly journals Model Test of Anchoring Effect on Zonal Disintegration in Deep Surrounding Rock Masses

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Xu-Guang Chen ◽  
Qiang-Yong Zhang ◽  
Yuan Wang ◽  
De-Jun Liu ◽  
Ning Zhang
Keyword(s):  
Model Test ◽  
Surrounding Rock ◽  
Zonal Disintegration ◽  
Formation Condition ◽  
Anchor Effect ◽  
Rock Masses ◽  
Tunnel Excavation ◽  
Anchoring Effect ◽  
Tension And Compression ◽  
Deep Rock

The deep rock masses show a different mechanical behavior compared with the shallow rock masses. They are classified into alternating fractured and intact zones during the excavation, which is known as zonal disintegration. Such phenomenon is a great disaster and will induce the different excavation and anchoring methodology. In this study, a 3D geomechanics model test was conducted to research the anchoring effect of zonal disintegration. The model was constructed with anchoring in a half and nonanchoring in the other half, to compare with each other. The optical extensometer and optical sensor were adopted to measure the displacement and strain changing law in the model test. The displacement laws of the deep surrounding rocks were obtained and found to be nonmonotonic versus the distance to the periphery. Zonal disintegration occurs in the area without anchoring and did not occur in the model under anchoring condition. By contrasting the phenomenon, the anchor effect of restraining zonal disintegration was revealed. And the formation condition of zonal disintegration was decided. In the procedure of tunnel excavation, the anchor strain was found to be alternation in tension and compression. It indicates that anchor will show the nonmonotonic law during suppressing the zonal disintegration.

Numerical Simulation of Zonal Disintegration of the Surrounding Rock Masses Around a Deep Circular Tunnel Under Dynamic Unloading

2015 ◽  
Vol 12 (03) ◽  
pp. 1550020 ◽  
Author(s):  
Jing Bi ◽  
Xiao Ping Zhou
Keyword(s):  
Strength Criterion ◽  
In Situ Stress ◽  
Zonal Disintegration ◽  
Rock Masses ◽  
Circular Tunnel ◽  
Dynamic Unloading ◽  
Deep Rock ◽  
Zonal Disintegration Phenomenon ◽  
Nonlinear Unified Strength Criterion ◽  
Deep Circular Tunnel

A new numerical method, which is called the General Particle Dynamics (GPD) method, is proposed to investigate the zonal disintegration mechanism of isotropic rock masses around a deep circular tunnel subjected to dynamic unloading as well as the stress distributions. A constitutive model based on the GPD method is developed to simulate the zonal disintegration phenomenon in deep rock masses. The number and size of fractured and nonfractured zones are determined using the nonlinear unified strength criterion. It is shown from the numerical results that the dynamic loads and high in situ stress are two dominant factors for the occurrence of zonal disintegration.

An Analytical Research on Stress-Wave Propagation and Comparison of Experiments and Theory of Zonal Disintegration in Rock Masses around Deep Tunnels

2020 ◽  
Vol 980 ◽  
pp. 333-345
Author(s):  
Xian Ren Zeng ◽  
Shi Hui You ◽  
Fang Li ◽  
Bijan Rahmani
Keyword(s):  
Wave Propagation ◽  
Stress Wave ◽  
Wave Amplitude ◽  
Stress Wave Propagation ◽  
Zonal Disintegration ◽  
Rock Masses ◽  
Comparison Of Experiments ◽  
Deep Rock ◽  
Analytical Research

The zonal disintegration mechanism in rock masses around deep tunnels is totally controversial. Because this phenomenon basically depends on the stress-wave amplitude, fluctuating and declining in rock masses particularly around deep tunnels. This paper intends to theoretically solve the problem of stress-wave propagation. For this purpose, a physical model of stress-wave propagation is established in rock masses around the deep tunnels. Further, the wave equation is solved for rock masses of deep tunnels. Taking Dingji Tunnel in southern of China as a case-study, the central radius of partition is calculated theoretically and compared with the measured results in rock masses around deep tunnels. The research results of this paper gives a certain promotes to the theory of zonal disintegration in rock masses and have certain guiding significance for deep rock engineering.

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.

Study on Failure of Rock Mass around Deep Tunnel

2011 ◽  
Vol 99-100 ◽  
pp. 370-374 ◽  
Author(s):  
Yue Hong Qian ◽  
Ting Ting Cheng ◽  
Xiang Ming Cao ◽  
Chun Ming Song
Keyword(s):  
Rock Mass ◽  
Stress Field ◽  
Failure Modes ◽  
Shear Failure ◽  
Simple Function ◽  
Tensile Failure ◽  
Deep Tunnel ◽  
Main Mode

During excavating the problem of unloading is a dynamic one essentially. Assuming the unloading ruled by a simple function and based on the Hamilton principal, the distribution of the stress field nearby the tunnel is obtained. The characteristics of the failure nearby the tunnel are analyzed considering the shear failure and tensile failure. The results show that the main mode of the shear failure, intact and tensile failure occurs from the tunnel. The characteristic of the shear failure, intact and tensile failure are one of the likely failure modes.

Numerical Study of P-Waves Propagating across Deep Rock Masses Based on the Hoek–Brown Model

2020 ◽  
Vol 20 (2) ◽  
pp. 04019152
Author(s):  
Yun Zheng ◽  
Congxin Chen ◽  
Tingting Liu ◽  
Wei Zhang
Keyword(s):  
Numerical Study ◽  
Rock Masses ◽  
P Waves ◽  
Deep Rock
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