Compressive performance of innovative reinforced pillars in closed/abandoned mines

关闭/废弃矿井新型加固矿柱的抗压性能

Pillar is closely related to the stability and reliability of underground spaces in closed/abandoned mines.The present research introduced a new technique to strengthen square cement mortar columns via fiber-reinforced polymer(FRP)strips to verify the strengthening effect of FRP on pillars.Compared to a fully wrapped FRP jacket,the advantages of FRP strip are cost-effective and easy-to-construct.A series of compression tests as well as theoretical analysis were carried out to explore the mechanical behavior of square cement mortar specimens partially strengthened with FRP strips.The results verified the effectiveness of FRP strips in enhancing the stress and strain of cement mortar.Different from unconfined cement mortar specimens,these FRP-strengthened cement mortar specimens are featured with the double-peaked behaviors,mainly attributed to the stress state transformation from a one-dimensional to a three-dimensional stress state.It also indicated that the enhancement of stress increased with the FRP strip width.Moreover,the brittle-ductile transition ductile failure characteristics were also observed in FRP-confined cement mortar specimens.The ultimate ductility of the cement mortar specimen decreases gradually with the growth of the FRP strip width.The main contribution of this research is to enrich the strengthening techniques for residual pillars.

矿柱与关闭/废弃矿井地下空间的稳定性和可靠性密切相关。本研究介绍了一种通过纤维增强聚合物(FRP)条带加固方形水泥砂浆柱的新技术,以验证FRP对矿柱的强化效果。与完全包裹FRP护套相比,FRP条带的优点是成本较低且易于施工。通过一系列压缩试验和理论分析,探讨了FRP条带局部加固方形水泥砂浆试样的力学性能。试验结果验证了FRP条带增强水泥砂浆柱峰值应力和应变的有效性。与无侧限水泥砂浆试样不同,FRP加固水泥砂浆试样具有双峰特性,主要是因为其应力状态从一维向三维应力状态转变。结果表明,试样的峰值应力随着FRP条带宽度的增加而增加。此外还观察到了其脆延转化特征。随着FRP条带宽度的增加,水泥砂浆试样的极限延性逐渐降低。本研究为遗留煤柱失稳加固提供了新选择。