顶升可缩式GFRP管混凝土组合支柱承载力试验研究

Experimental study on axial load-bearing capacity of grout-lifted compressible concrete-filled GFRP tube composite column

  • 摘要: 针对高地应力沿空巷道巷旁支护难题,提出了顶升可缩式GFRP (玻璃钢)管混凝土组合支柱结构,开展了不同上节管、径厚比、让压量下GFRP管混凝土组合支柱的室内轴压承载试验,系统分析了上节管材质、管径及让压结构对支柱承载性能的影响机制,组合支柱结构单位重量小,材料成本低,耐腐蚀性强,依据各支柱荷载−位移曲线、荷载−应变曲线及破坏特征对比分析了不同类别支柱的承载力与可缩性能。试验表明:顶升可缩式GFRP管混凝土组合支柱具备“增阻让压”性能,让压结构与核心混凝土耦合作用良好;GFRP管规格为ø220 mm×10 mm、ø270 mm×10 mm和ø320 mm×10 mm的相同长径比组合支柱,极限承载力为21803310 kN,极限可缩量为171~235 mm,达到让压结构初始高度(260 mm)的66%~90%,极限承载力与可缩量随GFRP管径增大而增加;为优化组合支柱受力结构,上节管材料选用钢管,GC−1、GC−2支柱极限承载力分别为2790 kN、2830 kN,极限可缩量分别为190 mm、195 mm,可缩式GFRP管−钢管混凝土组合支柱的承载性能及破坏特征较可缩式GFRP管混凝土组合支柱更优,组合支柱承载性能随钢管壁厚的增加而提高。基于支柱变形破坏特征分析了组合支柱协同承载机理并确定了不同类别组合支柱的极限破坏点,由此推导了顶升可缩式GFRP管混凝土组合支柱和可缩式GFRP管−钢管混凝土组合支柱的轴压极限承载力计算公式,预测组合支柱巷用承载力,为工程应用提供理论指导。

     

    Abstract: To address the challenges of roadway along gob support under high-stress conditions, a grout-lifted compressible GFRP (Glass Fiber Reinforced Plastic) tube concrete composite support column structure was proposed. Axial compression tests were conducted on GFRP tube concrete composite columns with varying upper tube materials, diameter-to-thickness ratios, and pressure-relief displacements. The mechanisms influencing the load-bearing performance of the columns, including upper tube material, tube diameter, and pressure-relief structure, were systematically analyzed. Composite support column exhibits low unit weight, low material cost, strong corrosion resistance. Based on load-displacement curves, load-strain curves, and failure characteristics, the load-bearing capacity and pressure-relief performance of different types of columns were compared.The test results indicate that the grout-lifted compressible GFRP tube concrete composite support column exhibits an "enhanced resistance and pressure-relief" performance, and good coupling between the pressure-relief structure and the core concrete. For composite columns with GFRP tubes of ø220 mm×10 mm, ø270 mm×10 mm, and ø320 mm×10 mm under the same slenderness ratio, the ultimate load-bearing capacity ranges from 2180 kN to 3310 kN, and the ultimate pressure-relief displacement ranges from 171 mm to 235 mm, reaching 66%–90% of the initial pressure-relief structure height (260 mm). Both the ultimate load-bearing capacity and pressure-relief displacement increase with the GFRP tube diameter.To optimize the load-bearing structure of the composite column, steel tubes were used as the upper tube material. For the GC–1 and GC−2 columns, the ultimate load-bearing capacities are 2790 kN and 2830 kN, respectively, and the ultimate pressure-relief displacements are 190 mm and 195 mm. The compressible GFRP-steel tube concrete composite support column demonstrated superior load-bearing performance and failure characteristics compared to the compressible GFRP tube concrete composite support column. The load-bearing performance of the composite column increases with the wall thickness of the steel tube.Based on the deformation and failure characteristics of the support column, the collaborative load-bearing mechanism of the composite column was analyzed, and the ultimate failure points of different types of composite columns were determined. Consequently, axial ultimate load-bearing capacity calculation formulas for grout-lifted compressible GFRP tube concrete composite support columns and compressible GFRP-steel tube concrete composite support columns were derived. These formulas predict the load-bearing capacity of composite support columns in roadway along gob applications, providing theoretical guidance for engineering applications.

     

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