Floor heave and serious track bed cracking deformation occurred in the invert of a tunnel in southwestern China,with rapid heaving rates posing significant operational safety hazards.To address the issue of floor heave in ballastless track tunnels along operational lines efficiently and safely,field investigations,borehole verifications,and supplementary geological explorations were conducted to assess the existing tunnel structure's status and identify the causes of the defects.An optimal remediation strategy was then selected.The findings are as follows:(1)Through a comprehensive analysis of factors including the degree of defect development,groundwater conditions,concrete condition,surrounding rock stress,and structural deformation,it was deduced that the interaction between gently dipping weak rock layers and groundwater under complex crustal stress environments is the primary cause of heaving in this tunnel.(2)Various remediation options,including grouting reinforcement of the tunnel floor,micro-piles of the tunnel floor,raft foundation of the tunnel floor,tensile anchor(cable)in the track bed,and replacement and reinforcement and deepening of the tunnel floor,were compared.Ultimately,the solution of increasing the span-to-rise ratio and reconstructing the tunnel floor by deepening and reinforcing was adopted.(3)During construction,emergency management was intensified,and designs were timely optimized and adjusted based on settlement monitoring,stress monitoring,and surrounding rock displacement monitoring data analyses.The post-treatment effects proved satisfactory.The experiences gathered from this study can serve as a reference for future projects.
complex crustal stress environmentinvert floor heavesettlement monitoringspan-to-rise ratio
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