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.

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.

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