以钢管混凝土支架支护深井软岩巷道为背景,对钢管混凝土支架组成构件中的四分之一圆弧拱进行六分点等值加载,以研究试验试件的矢跨比和钢纤维体积掺量对试件力学性能的影响。实验表明,钢管混凝土圆弧拱试件拱底处主要受压弯剪应力影响,最先发生局部破坏;拱顶处主要受压应力影响,拱底和拱顶均为试件最薄弱截面。矢跨比越大,能够承受的荷载和刚度越大。1%~1.5%钢纤维体积掺量的试件的柔性增强,极限荷载与无钢纤维试件差别不大。继续增加钢纤维掺量,试件刚度增加,但试件极限荷载降低,钢纤维体积掺量在1%~1.5%较为合适。再通过数值模拟进一步研究试件危险截面的受力形式和试件的截面尺寸、矢跨比、壁厚对承载力的影响。与此同时,结合试验分析和数值模拟结果,从试件截面强度、局部失稳、整体失稳三方面进行理论分析,给出钢管混凝土圆弧拱局部失稳的原因和承载力的计算公式。最后,结合实际工程情况,提出钢管混凝土设计方案。

Based on the concrete-filled steel tube (CFST) supporting structure used in deep-seated soft rock roadway, six equivalent loads are loaded on the 1 / 4 CFST circular arches. The influence of mechanical properties with different rise-span ratios and steel fiber volume parameters are studied. The experimental results show that the bottom of CFST circular arch is damaged by compressing,bending and shearing. The apex of arch is mainly influenced by compressive stress. Both apex and bottom of the arch are the weakest cross sections. The bearing load and the stiffness of structure are enhanced with the increase in rise-span ratios. The flexibility is increased in test specimen with 1% -1. 5% steel fiber volume parameters while little difference can be found in ultimate load in contrast to the one without steel fiber. With continuing increase in steel fiber volume,the stiffness of specimen is increasing and ultimate load is decreasing. Therefore,1% -1. 5% volume parameter of the steel fiber is suitable. Besides,by using numerical simulation,the stress forms of the dangerous sections of the specimens and the influence of bearing capacity on the section dimension,rise span ration,wall thickness of steel tubes are further studied. Meanwhile,combined with the experimental analysis and numerical results,theoretical analysis is proposed from three aspects:Section strength,local instability and overall in- stability. The cause of local instability and calculation formula for the ultimate bearing capacity of circular arch CFST are obtained. Finally,on the basis of practical engineering condition,the design example of CFST is introduced.