Determination of the load bearing capacity of pre-stressed expandable props for ground support in underground mines  

作　　者：Kunmeng Li Kaiyuan Jiang Yuanhui Li Xin Wang Kai Liu Shuai Xu 

机构地区：[1]Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,School of Resources and Civil Engineering,Northeastern University,Shenyang 110819,China [2]Key Laboratory of Liaoning Province on Deep Engineering and Intelligent Technology,School of Resources and Civil Engineering,Northeastern University,Shenyang 110819,China [3]China-Canada Centre of Deep Mining Innovation,Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,School of Resources and Civil Engineering,Northeastern University,Shenyang 110819,China [4]Department of Engineering Science,University of Oxford,Oxford OX13PJ,United Kingdom

出　　处：《International Journal of Mining Science and Technology》2023年第8期977-990,共14页矿业科学技术学报（英文版）

基　　金：This work was financially supported by the National Key Research and Development Program of China(No.2022YFC2903804);the National Natural Science Foundation of China(Nos.52004054,52274115,51874068 and 52074062).

摘　　要：This paper aims to determine the load bearing capacity of pre-stressed expandable props with different geometries and load eccentricities for flexible support in underground mining or excavation.It is deduced that the expandable device could have much higher strength(>89 MPa)by laboratory tests,and the load bearing capacity of the expandable prop may depend on the stability of the supporting steel pipe structure.A good agreement was found between the laboratory test and numerical results in terms of the load bearing capacity and the final macro-bending failure pattern for expandable props with heights of 1.5 and 2.7 m,and the theoretical calculation for the strength of traditional steel structures is not directly suitable for the expandable props.Moreover,additional numerical simulations were performed for the expandable props with different normalized slenderness ratiosλ_(n)and loading eccentric distances e.The variation of stability coefficient of the expandable prop is in line with the Perry-Robertson equation and its correlation coefficients are fitted as a of 0.979 and b of 0.314.For estimating the load bearing capacity of the expandable props,the strength equation for traditional steel structures is improved by introducing a bending magnification factor and by modifying the normalized slenderness ratio to a converted slenderness ratio.Based on the underground field monitoring for the strength of expandable props with different heights,the empirical eccentric distances were back calculated,and a safety factor is introduced to obtain the designed strength of the expandable prop.In addition,a four-step design procedure is proposed for the expandable prop.

关 键 词：Pillar stability Load bearing capacity Expandable prop Slenderness ratio Eccentric distance 

分 类 号：TD35[矿业工程—矿井建设]