Optimization of rock bolt parameters for existing tunnel with different expansion widths
YANG Jun1, CHENG Hao2, XIE Zhigang3, DING Xuefei3, LIANG Yong3
(1. Collaborative Innovation Center of Geological Hazards and Ecological Environment in Three Gorges Area in Hubei Province, China Three Gorges University, Yichang, Hubei 443002, China; 2. Fifth Engineering Branch, CCCC Second Shipping Engineering Bureau Co., Ltd., Wuhan, Hubei 430050, China; 3. Yiling District Highway Administration Bureau of Yichang City, Yichang, Hubei 443100, China)
Abstract：Based on Huangshandong Tunnel project, field data monitoring and numerical simulation by finite element analysis software of Midas GTS NX were used to analyze the laws of vault settlement, peripheral convergence and effective stress change of surrounding rock under different expansion widths. The length and ring distance of anchor bolts were changed to discuss the variation laws of effective surrounding rock stress, lining stress and bolt stress under different bolt lengths, and the optimal bolt length and bolt spacing under different expansion widths were determined. The results show that the decreasing sequence of effective surrounding rock stress is the compressive stress at the arch foot, the compressive stress at the arch waist, the compressive stress at the arch top and the tensile stress at the invert. With the increasing of excavation width, the compressive stress at the top of arch is decreased, while the compressive stress at the waist is increased with unconspicuous increasing trend. Under the influence of the single-side expansion mode, the stress of expansion side is greater than that of the non-expansion side. Due to the influence of stress concentration, the compressive stress at the arch foot is increased with the increasing of excavation width. For the expansion width of 1.5-2.5 m, the length and spacing of the anchor rod are respective 2.5 m and 1.7 m, and for the expansion width of 3.5-4.5 m, the length and spacing of the anchor rod are respective 3.0 m and 1.2 m.
LIN C M, ZHANG Z C, ZHENG Q, et al. Study on the soft surrounding rocks stability and supporting parameters of two-to-fourlane tunnel of small clear-distance by CD method[J].China Civil Engineering Journal, 2013,46(7):124-132.（in Chinese）
CHEN X L, LI H, CHEN J. Numerical analysis of influence of bolt parameters on the stability of surrounding rock[J]. Low Temperature Architecture Technology,2010,32(6):101-103.（in Chinese）
XU L G, LI H, CHEN X L, et al. Numerical analysis on the impact of rock bolt parameters on stability of surrounding rock[J].Chinese Journal of Geotechnical Engineering,2010,32(Sup 2):249-252.（in Chinese）
WANG Z W, SONG M Y, JIN H, et al. Study on optimal anchor spacing of class IV surrounding rock tunnel with three lanes［J］. Railway Construction Technology, 2018(12): 86-92.（in Chinese）
［7］
李文江，朱永全,李帅，等.隧道力学［M］.北京：机械工业出版社，2013:63.
［8］
金洋洋. 隧道锚杆支护参数优化分析［D］.重庆：重庆交通大学,2015.
［9］
蒋剑蓬.隧道锚杆支护机理及关键问题探讨［J］.中国新技术新产品,2012(9):33.
JIANG J P. Discussion on mechanism and key problems of tunnel bolting［J］. China New Technologies and New Products,2012(9):33.（in Chinese）
YANG K W, LYU G, YU C Y, et al. Analysis of bolt′s action mechanism in the tunnel initial support system［J］. Railway Investigation and Surveying, 2019,45(1):47-52.（in Chinese）
CHEN N Q, YANG W X. Study on the action mechanism of radial bolt in tunnel surrounding rock［J］. Science & Technology Information, 2006(11): 243-246.（in Chinese）
