加载速率对分层充填体强度特性的影响

Effect of Loading Rate on Strength Characteristics of Layered Backfill

随着阶段嗣后充填采矿法的广泛应用,相邻矿体的开采扰动必然会对分层充填体的力学性能产生影响。为了研究不同加载速率对分层充填体强度特性和破坏模式的影响,对不同养护龄期的分层充填体进行了5种加载速率(0.2、0.5、1.0、1.5、2.0 mm/min)下的单轴压缩试验,分析了分层充填体强度及破坏模式与加载速率之间的关系并建立了回归方程。试验结果表明:养护龄期3 d时,分层充填体的单轴抗压强度随加载速率的增加而逐渐减小,养护龄期7、28 d时,存在临界加载速率现象。随着加载速率的增加,养护3 d时,分层充填体的破坏模式由拉伸剪切混合破坏变为拉伸破坏。养护7、28 d时,当达到临界加载速率时破坏模式转变共轭剪切破坏,中间层破坏严重且与上下两层产生明显分离、错动。通过室内试验得到临界加载速率,为研究分层充填体的强度特性提供了重要的研究依据。

With the wide application of stage-subsequent filling mining method,the mining disturbance of adjacent orebodies will inevitably affect the mechanical properties of layered filling body.In order to study the influence of different loading rates on the strength characteristics and failure modes of layered fillings,uniaxial compression tests were carried out on layered fillings with different curing ages at five loading rates of 0.2,0.5,1.0,1.5 and 2.0 mm/min.The relationship between the strength and failure modes of layered fillings and the loading rates was analyzed and the regression equation was established.The test results show that the uniaxial compressive strength of layered backfill decreases with the increase of loading rate at 3 days of curing age,and the critical loading rate phenomenon is appeared at 7 and 28 days of curing age.As the loading rate increases,the failure mode of layered backfill changed from tensile shear mixed failure to tensile failure after being cured for 3 days.After being cured for 7 and 28 days,when the critical loading rate is reached,the failure mode is transformed into conjugate shear failure,and the middle layer is seriously damaged,which is obviously separated and dislocated from the upper and lower layers.In this study,the critical loading rate is obtained by laboratory test,which provides an important research basis for studying the strength characteristics of layered backfill.