Study on the Reinforcement Measures and Control Effect of the Surrounding Rock Stability Based on the Shield Tunneling Under Overpass Structure

• Main Authors: Qian-cheng Fang, Li Shang, Yong-hui Shang, Ying Zhao, Ning-yi OU
• Format: Article
• Language: English
• Published: Eastern Macedonia and Thrace Institute of Technology 2016-04-01
• Series: Journal of Engineering Science and Technology Review
• Subjects: Shield; Overpass Structure; Surrounding Rock; Control Effect; Safety Factor
• Online Access: http://www.jestr.org/downloads/Volume9Issue1/fulltext91202016.pdf

To study the stability of surrounding rocks for shield tunneling under overpass structures and the safety of existing bridge structures, a practical example of the method was cited through a shield tunneling project under the overpass structure between K1+110 and K1+700 on Line 2 of Shenyang Subway, China. The sub-area reinforcement was proposed according to surrounding rock deformation characteristics during shield tunnel excavation. The bridge foundation (i.e., the clear spacing to the shield tunnel is less than 2 m) was reinforced by steel support, the bridge foundation (the clear spacing is about 2~7m) used “jet grouting pile” reinforcement, whereas the bridge foundation (the clear spacing is greater than 7 m) did not adopt any reinforcement measures for the moment. For this study, the mean value and material heterogeneity models were established to evaluate the reinforcement effect from several aspects, such as surrounding rock deformation, plastic zone development, and safety factor. The simulation results were consistent with those of field monitoring. After reinforcement, the maximum deformation values of the surrounding rock were reduced by 4.9%, 12.2%, and 48.46%, and the maximum values of surface subsidence were decreased by 5.6%, 72.2%, and 88.64%. By contrast, the overall safety factor was increased by 4.1%, 55.46%, and 55.46%. This study posited that this reinforcement method can be adopted to solve tunnel construction problems in engineering-geological conditions effectively. References for evaluating similar projects are provided.