矩形大断面超浅埋暗挖地下通道钢拱架内力分析试验研究

Testing study on internal force analysis of steel arch structure with ultra-shallow buried excavation underground passage in rectangular section

以某矩形大断面超浅埋暗挖地下通道为工程背景,通过现场试验及分析,探讨钢拱架内力随掌子面开挖距离的变化规律,对设计时的弹性支点计算范围进行分析,研究钢拱架与喷射混凝土墙体的协同承载能力。研究结果表明:(1)钢拱架的轴力与弯矩随其与掌子面间距变化可分为两个阶段:轴力在1.0m^16.0m期间增大,在大于16.0m后轴力值趋于稳定,弯矩在1.0m^12.0m急速增加,在大于12.0m后弯矩值趋于稳定;(2)设计时应考虑喷射混凝土墙体和钢拱架的共同作用,可认为初支荷载钢拱架承担75%,其余25%由混凝土墙体承担,建议设计时对钢拱架优化处理;(3)采用弹性地基梁法时,可考虑将弹性支点计算范围扩大到封闭成环后10m范围;(4)采用弹性地基梁法设计时尽管可以考虑到管棚和钢拱架协同作用,但参数取值至关重要,应引起重视。

Taking the ultra-shallow buried excavation project of the large rectangular section of the underground passage for Engineering background,Through the field test and analysis,the variation law of the internal force of the steel arch with the excavation distance is discussed,the calculation range of the elastic fulcrum in the design is analyzed,and the cooperative bearing capacity of the steel arch and the shotcrete wall is studied. The results show that：（1） the axial force and bending moment of the steel arch can be divided into 2 stages： the axial force increases in the period of 1. 0 m - 16. 0 m,and the axial force tends to be stable after more than 16. 0 m,the bending moment increases rapidly at 1. 0 m - 12. 0 m,and the moment value tends to be stable after more than 12. 0 m,and the design of the shotcrete wall should be considered when the design is more than 12. 0 m;（2）the joint action of the steel arch can be considered as 75% of the initial support load steel arch and the rest 25% of the concrete wall,and the steel arch frame should be optimized in designed;（3）when the elastic foundation beam method is adopted,the calculation range of the elastic pivot can be extended to the 10 m range after the closure of the ring;（4） the synergistic effect of pipe roof and steel arch should be considered,but the critical parameters should be paid attention to.