Risk Control and Safety Evaluation of Lake-crossing Shield Tunnels
Under the construction of shield tunneling between Yaohu East Station and Yaohu West Station of Nanchang Rail Transit Line 1,which encounters poor geology such as a water-rich sand layer,an uneven layer of top soft and bottom hard,and a soft soil layer,it is vulnerable to causing engineering accidents including spillage,shield floating on board,instability of the shield tunnel face,ground subsidence,ground subsidence and collapse and collapse.The risk control system is built,and the safety assessment is carried out by WBS-RBS risk identification approach.The research results indicate that the measures of end foundation reinforcement and precipitation,optimization of shield tunneling parameters,control of shield attitude and tunneling rate,and application of information in construction can effectively prevent the risks of gushing,soft soil collapse,shield floating,and shield eccentricity.The overall risk rating of the shield section has been decreased from class Ⅱ to class Ⅲ or below,guaranteeing the safe and efficient tunneling of the shield tunnel throughout lake-crossing.The construction scheme of the lake-crossing shield tunnel in this paper can be used as a reference for future shield tunnel construction.
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