不同宽高比矿柱偏心压缩失稳破坏规律研究

Study on the Failure Law of Eccentric Compression Instability of Pillars with Different Width-height Ratios

研究非等跨采场结构下,矿柱偏心压缩失稳破坏规律,可以为矿柱结构参数优化提供技术支撑。通过偏心加载装置,以岩样模拟矿柱,开展了不同宽高比岩样偏心压缩试验。结合数字图像相关方法,得到了宽高比(w/h)分别为2∶1、1∶1、1∶2和1∶3时矿柱偏心承载性能和加载过程中位移场及应变场的演化规律。结果表明:①偏心压缩条件下,矿柱抗压强度随着宽高比增加逐渐增加,弹性模量则反之;在考虑偏心荷载作用的矿柱设计时,应适当增加矿柱宽高比,从而保障采场安全性。②当w/h=2∶1时,偏心承载矿柱破坏形式主要为压剪破坏,表现为偏心荷载侧局部劈裂破坏;当w/h=1∶1时,矿柱以压缩破坏为主拉伸破坏为辅;当w/h<1∶2时,矿柱破坏以偏心拉伸破坏为主。③不同宽高比矿柱的水平位移场在距偏心荷载较远一侧发生较大变形,剪切应变场也为压—拉应变场;当w/h≥1∶2时,矿柱的破坏主要是由压应变局部化带引发;w/h=1∶3时,矿柱破坏主要由拉应变局部化带引发。

The study of the influence of pillar eccentric compression instability and failure mode in non-equal-span stope structures can provide technical support for the optimization of pillar parameters.By using an eccentric loading device,rock samples were used instead of pillars to conduct eccentric compression experiments on samples with different width-height ratios.Combined with the digital image correlation methods,the bearing capacity of pillars with width-height ratios(w/h)of 2∶1,1∶1,1∶2,and 1∶3 were obtained,as well as the evolution of displacement and strain fields during the loading process.The results show that:①Under eccentric compression conditions,the compressive strength of the pillar increases with the increase of width-height ratio,while the elastic modulus is the opposite.In the design of pillars considering eccentric load,the width-height ratio of pillars should be appropriately increased to ensure the safety of stope.②When w/h=2∶1,the failure mode of eccentric bearing pillars is mainly compression-shear failure,manifested as local splitting failure on the eccentric load side.When w/h=1∶1,the pillars are mainly subjected to compression failure and supplemented by tensile failure.When w/h=1∶1,the failure of pillars is mainly caused by eccentric tensile failure.③The horizontal displacement field of pillars with different width-height ratios undergoes significant deformation on the side far from the eccentric load,and the shear strain field is also a compressivetensile strain field.When w/h≥1∶2,the failure of the pillar is mainly caused by the localized zone of compressive strain.When w/h=1∶3,the failure of the pillar is caused by the localized zone of tensile strain.