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Geomechanics and Engineering
  Volume 29, Number 2, April25 2022 , pages 113-131
DOI: https://doi.org/10.12989/gae.2022.29.2.113
 


Modeling of a rockburst related to anomalously low friction effects in great depth
J.W. Zhan, G.X. Jin, C.S. Xu, H.Q. Yang, J.F. Liu and X.D. Zhang

 
Abstract
    A rockburst is a common disaster in deep-tunnel excavation engineering, especially for high-geostress areas. An anomalously low friction effect is one of the most important inducements of rockbursts. To elucidate the correlation between an anomalously low friction effect and a rockburst, we establish a two-dimensional prediction model that considers the discontinuous structure of a rock mass. The degree of freedom of the rotation angle is introduced, thus the motion equations of the blocks under the influence of a transient disturbing force are acquired according to the interactions of the blocks. Based on the two-dimensional discontinuous block model of deep rock mass, a rockburst prediction model is established, and the initiation process of ultra-low friction rockburst is analyzed. In addition, the intensity of a rockburst, including the location, depth, area, and velocity of ejection fragments, can be determined quantitatively using the proposed prediction model. Then, through a specific example, the effects of geomechanical parameters such as the different principal stress ratios, the material properties, a dip of principal stress on the occurrence form and range of rockburst are analyzed. The results indicate that under dynamic disturbance, stress variation on the structural surface in a deep rock mass may directly give rise to a rockburst. The formation of rockburst is characterized by three stages: the appearance of cracks that result from the tension or compression failure of the deformation block, the transformation of strain energy of rock blocks to kinetic energy, and the ejection of some of the free blocks from the surrounding rock mass. Finally, the two-dimensional rockburst prediction model is applied to the construction drainage tunnel project of Jinping II hydropower station. Through the comparison with the field measured rockburst data and UDEC simulation results, it shows that the model in this paper is in good agreement with the actual working conditions, which verifies the accuracy of the model in this paper.
 
Key Words
    anomalously low friction; intensity; prediction model; rockburst; tunnel
 
Address
J.W. Zhan: College of Civil Engineering, Fujian University of Technology, Fuzhou, China
G.X. Jin: College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou, China
C.S. Xu: School of Civil, Environment and Mining Engineering, the University of Adelaide, Adelaide
H.Q. Yang and J.F. Liu: School of Civil Engineering, Chongqing University, Chongqing, China
X.D. Zhang: College of Civil Engineering, Fuzhou University, Fuzhou, China
 

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