曲线盾构隧道施工稳定性及致险水平研究

Study on stability influential factors and risk level classification of shield tunnel with small radius curve

小曲率半径盾构隧道施工稳定性影响因素错综复杂,对不同评价指标的作用规律及致险等级差异显著。以济南厚冲洪积地层为地质条件,基于正交试验建立了5因素4水平6指标的小半径盾构施工稳定性综合评价体系,通过多影响因素的定量分析与定性评价,确定了其敏感性排序及致险水平等级。结果表明:隧道埋深与盾构直径对地层变形具有强烈致险作用,随埋深的增大,地表最大沉降值与沉降槽宽度呈线性递增;隧道曲率半径及千斤顶不平衡推力对曲线盾构地表沉降槽偏移与管片两侧差异变形影响显著,随曲率半径的增大,地表沉降峰值点偏移量与管片两侧变形差呈线性递减,管片最大拉应力呈二次函数递减。研究成果对曲线盾构隧道施工的参数评价及风险防控具有重要指导意义。

The stability influential factors of small radius curve shield tunnel,which have significant variation of impacting effect and risk rank on different evaluation indicators,are intricate and complex. Combining Jinan engineering geological characteristics of thick alluvial clay strata,a comprehensive evaluation system for construction stability of small radius curve tunnel was established with 5 factors 4 levels and 6 indicators based on the orthogonal test. The sensitivity order and risk level rank of influential factors were obtained by quantitative analysis and qualitative evaluation for multiple influential factors. The results show that tunnel depth and shield diameter play an intense risk role on stratum deformation that ground surface settling tank width and maximum settlement increase linearly with the increase of buried depth. Tunnel radius of curvature and jack unbalanced force have significant effects on the non-uniform deformation of segment deformation and surface subsidence trough migration,that as the radius of curvature increases,the maximum ground settlement offset and segment deformation difference on both sides are linear slowly decreasing,and segment maximum tensile stress present a quadratic function decreases. The research results are of important guiding significance to the construction parameters evaluation and risk prevention and control for the small radius curve tunnel.