重复采动条件下坚硬顶板力学试验研究

Study of the hard roof mechanical properties in the process of repeated coal mining

基于能反映岩体非线性破坏的Hoek-Brown准则对重复采动上覆坚硬顶板力学特性进行研究.利用MTS 815岩石伺服试验系统对不同损伤状态的坚硬顶板岩样进行加载试验,分析了坚硬顶板在不同损伤程度下的强度与围压的函数关系;得到了不同损伤程度下的m,s值并建立了以m,s的降低率ηm,ηs表征坚硬顶板损伤程度的参量,最后对现场顶板宏观破坏特征进行统计.结果表明:损伤岩样的强度与围压多数呈二次函数关系;重复采动造成m,s均呈不同程度降低,但ηm,ηs均呈增大趋势且ηm>ηs;覆岩裂隙带钻孔漏失量明显增大,裂隙带空间分布形态发生显著变化.

Based on the Hoek-Brown criterion which can reflect the nonlinear failure of the rock mass,the mechanical properties of hard roof were studied.The hard roof rock sample loading test with MTS 815 rock servo test system for different damage states was performed.The relationship between strength and confining pressure of hard roof under different damage degree was analyzed,the m,s values of different damage degree were obtained,the decrease rates of mand s were established to represent the damage degree of hard roof.Finally,the macroscopic failure characteristics of the hard roof were analyzed.The results show that the strength and confining pressure of the rock samples are the quadratic function;repeated mining caused m and s to be reduced in different degrees,butηm,ηsare both increasing andηm ηs;the hole leakage of overburden fractures is obviously increased,the spatial distribution of mining fissure zone changed obviously.