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151 results on '"Wu, Xuezhen"'

21. Numerical investigation of bolted rock joints under varying normal stress and joint roughness coefficient conditions.

Author

Wang, Zhiyong, Liao, Liyun, Guo, Shiyi, Zheng, Hanfang, and Wu, Xuezhen

Subjects
SHEAR (Mechanics), BOLTED joints, DISCRETE element method, DEFORMATION of surfaces, GRANULAR flow, ROCK bolts
Abstract

Rock masses are formed through long-term, complex geological processes, and the presence of joints significantly reduces their strength and increases their deformation. Rock bolts effectively enhance the strength and stability of rock masses and are extensively utilized for reinforcement. According to field investigations, a significant portion of the damage to bolted rock masses stems from shear deformation at joint surfaces. Moreover, roughness affects friction and surface contact, thus influencing the shear behavior between rock and rock bolts. This study considers two crucial factors affecting the shear characteristics of bolted rock joints: joint surface roughness and normal stress. Using the Particle Flow Code discrete element numerical method, the Barton standard joint profile lines were input to establish numerical models of both unbolted and bolted rock joints for direct shear tests. Results reveal that the peak shear stress and stiffness of both unbolted and bolted rock joints increase with rising normal stress and joint roughness coefficient. The peak shear stress and stiffness of bolted rock joints are notably higher than those of unbolted ones, with a maximum increase of 17.5%. Crack development in bolted rock joints occurs in stages of rapid, slow, and stable development, whereas no distinct slow development stage is observed in unbolted rock joints. Additionally, micro cracks in both unbolted and bolted rock joints are primarily tensile cracks, originating around the joint surface and extending outward with increasing shear displacement. These findings offer valuable insights into the microscopic shear mechanics of bolted rock joints and provide practical references for engineering design and applications in rock reinforcement projects. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Influence of confining pressure-dependent Young’s modulus on the convergence of underground excavation

Author

Yujing Jiang, Wu Xuezhen, Bin Gong, and Guan Zhenchang

Subjects
Underground excavation, 0211 other engineering and technologies, Modulus, Young's modulus, 02 engineering and technology, Building and Construction, Numerical simulation, Plasticity, 010502 geochemistry & geophysics, Geotechnical Engineering and Engineering Geology, Overburden pressure, 01 natural sciences, Confining pressure, Stress (mechanics), symbols.namesake, Semi-analytical solution, symbols, Geotechnical engineering, Deformation (engineering), Rock mass classification, Geology, 021101 geological & geomatics engineering, 0105 earth and related environmental sciences, Plane stress
Abstract

The actual convergence of an excavation located in fractured rock mass or the soft rock is largely different with the theoretical result in many cases. Experimental results showed that the influence of confining pressure on Young's modulus is very significant. This paper attempted to illustrate the influence of the confining pressure-dependent Young's modulus in the ground reaction analyses of mountain tunnel. Firstly, the relationship between Young's modulus and confining pressure was described as a non-linear function according to the test results. Based on the plane strain axial symmetry assumption and the incremental theory of plasticity, equilibrium equations and compatibility equations of rock mass around a circular tunnel were deduced theoretically. Based on fourth Runge-Kutta method, a semi-analytical solution was achieved. Considering the effect of confining pressure on Young's modulus, the stress and deformation of rock mass around tunnel was calculated by both analytical and numerical methods. The influence of confining pressure-dependent Young's modulus in surrounding rock was estimated quantitatively. Finally, Tawara saka Tunnel in Japan was taken as an example to explain the influence of confining pressure-dependent Young's modulus. The results showed that the error with respect to the monitoring data was largely reduced with the confining pressure-dependent Young's modulus model, which indicated the necessity of considering the non-uniform distribution of Young's modulus., Tunnelling and Underground Space Technology, 83, pp.135-144; 2019

Published
2018

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