软弱地层开挖荷载引起管棚内力敏感度分析

Design Sensitivity Analysis of Pipe Roof Inner Force Induced by Excavation Release Load in Soft Ground

为了解管棚直径对管棚作用效果的影响,针对软弱地层浅埋暗挖法施工中管棚分析模型,采用解析法推导了单开挖步序地层释放荷载引起管棚内力对管棚惯性矩的敏感度分析方程.就我国常用的管棚直径情况,对内力敏感度及其主要影响因素进行了分析.分析表明:管棚直径从79 mm到108 mm范围内,为内力敏感度急剧变化范围,在该范围内,管棚直径的提高对于管棚内力影响较为显著;直径108 mm以上,管棚直径改变对于内力敏感度影响相对较小;超过159 mm直径,对于内力敏感度几乎没有影响.棚架体系中,作为刚度较大的支护条件改变对内力敏感度影响相对较大.

Based on the analysis model of pipe roof applied in the cutting under shallow overburden in soft ground, the analytical sensitivity analysis equation of bending moment induced by excavation release load is developed. The sensitivity of bending moment with respect to inertia moment of pipe roof and some factors, including the pipe roof diameter, soil layer parameters and support stiffness, are analyzed. It shows that when pipe roof diameter varies from 79 mm to 108 mm, the inner force sensitivity varies dramatically. When pipe diameter is larger than 108 ram, the inner force sensitivity varies less dramatically. When the diameter of piperoof is over 159mm, the increase of diameter has no effect on the inner force sensitivity of piperoof; In the pipe -support system, support stiffness has more effect on bending moment sensitivity than the ground properties.