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针对600～800 m巨厚冲积层中煤矿立井井筒的支护问题,提出了采用钢骨钢纤维高强混凝土井壁结构型式.为了研究该种井壁结构的水平极限承载特性,根据相似理论,采用物理模拟试验的方法,开展了2个模型井壁的破坏性试验,研究了该种井壁结构的水平极限承载特性和变形破坏特征.试验研究表明:在竖向荷载(井壁自重应力)加载阶段,钢骨和混凝土能够协同变形;水平荷载加载阶段,钢骨应变达到屈服应变后,钢骨表现出一定的塑性流动变形能力;井壁破坏时,钢骨和混凝土的切向应变值可达-3500×10-6(压);利用厚壁圆筒的弹性、塑性极限承载力估算井壁的水平极限承载力上、下限值,试验值更接近塑性极限承载力;由于钢骨和钢纤维的加入使得高强混凝土的脆性得到改善,钢骨钢纤维高强混凝土井壁具有更好的塑性变形能力和延性,是深厚表土层中一种可行的井壁结构型式.
In order to support the shaft support of coal mine shaft in 600-800 m thick alluvium, a steel fiber reinforced high-strength concrete beam-wall structure is proposed.In order to study the horizontal ultimate bearing capacity of this kind of shaft wall structure, according to the similarity theory, Physical simulation test, two destructive tests on the borehole wall were carried out, and the horizontal ultimate bearing capacity and deformation failure characteristics of the borehole wall structure were studied.The experimental results show that under vertical load (self-weight stress) In the stage of horizontal load loading, the steel billet shows a certain degree of plastic flow deformation after the steel strain reaches the yield strain. When the borehole wall is damaged, the tangential strain of the steel billet and the concrete reaches up to -3500 × 10-6 (pressure). The upper and lower limit values of the horizontal ultimate bearing capacity of wellbore are estimated by the elastic and plastic ultimate bearing capacity of thick-walled cylinder. The test values are closer to the plastic ultimate bearing capacity. With the addition of fiber, the brittleness of high strength concrete is improved. The steel fiber reinforced high-strength concrete shaft wall has better plastic deformation capacity and ductility. It is a viable wall structure type in deep topsoil formula.