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| SYSTEM RELIABILITY ANALYSIS OF ROCK SLOPES CONSIDERING ROCK BOLT CORROSION |
| LI Dianqing1，2，JIANG Shuihua1，2，ZHANG Limin3，ZHOU Chuangbing1，2 |
(1. State Key Laboratory of Water Resources and Hydropower Engineering Science，Wuhan University，Wuhan，Hubei 430072，China；2. Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering，Ministry of Education，Wuhan University，Wuhan，Hubei 430072，China；3. Department of Civil and Environmental Engineering，The Hong Kong University of Science
and Technology，Kowloon，Hong Kong，China) |
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Abstract A large number of engineering accidents have demonstrated that the failures of rock bolts are mainly induced by the corrosion of reinforcing steel bars. This study aims to investigate the effect of rock bolt corrosion on the system reliability of anchored rock slopes. A uniform corrosion model for rock bolts and its applicable environmental conditions are first examined based on systematical analysis of the existing corrosion models for reinforcing steel bars and the experiment data for rock bolt corrosion. Two failure modes related to rock bolt corrosion are determined. They are the yield failure mode of rock bolts at free section and the bond failure mode at the bolt-grout interface，respectively. Then，the failure models of anchored rock slope corresponding to those of rock bolts are established. A method for estimating the time-variant system reliability of rock slopes based on Monte Carlo simulation is presented. Consequently，an example of anchored rock slope with a single slip surface is presented to demonstrate the validity and capability of the proposed methods. The results indicate that the corrosion model proposed by K. A. T. Vu and M. G. Stewart is suitable for rock bolts subjected to environmental conditions of humidity and drying/wetting cycles. The rock bolt corrosion at free section has a more significant influence on the stability of rock slopes at the early stage，whereas the effect of rock bolt corrosion at anchored section becomes more obvious at the later stage. Moreover，the variations in the anchored force of each rock bolt and the system probability of slope failure at the later stage are more significant than those at the early stage. The system probability of slope failure decreases with the increasing thickness of the rock bolt cover，while increases with the increasing water-to-cement ratio of the grout. However，the system probability of slope failure does not significantly increase with time，when the thickness of the rock bolt cover and water-to-cement ratio of the grout reach certain values，respectively.
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Received: 11 January 2013
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2013, Vol. 32 
