超细尾矿充填体动力学性质试验研究

Experimental Study on Dynamic Properties of Ultra-fine Tailings Filling Body

在地下开采中,充填体会受到爆破振动等动载荷的扰动,严重威胁其稳定性,加之充填体使用超细尾矿后,会进一步降低其强度,因此,急需开展超细粒尾矿胶结充填体动力学性质研究。以超细尾矿充填体与粗尾矿充填体为研究对象,采用霍普金森装置对其进行不同应变率下的冲击试验,并进行对比分析。研究结果表明:与粗尾矿充填体相比,超细尾矿充填体弹性阶段较短,进入屈服阶段后,由于内部孔隙被压缩提升了其强度与抗变形能力,使其屈服阶段较长。粗尾矿充填体的破坏阶段表现出应力跌落现象,超细尾矿充填体在破坏阶段则表现出峰后塑性。平均应变率相近的超细尾矿充填体动态抗压强度远小于粗尾矿充填体动态抗压强度,超细尾矿充填体和粗尾矿充填体的平均应变率分别达到60s^(-1)和80s^(-1)左右后,动态抗压强度趋于平缓。随着平均应变率的增大,超细尾矿充填体的单位体积吸收能不断增加,粗尾矿充填体的单位体积吸收能在平均应变率超过80s^(-1)后才显著增加。在平均应变率相近时,超细尾矿充填体的破坏程度明显大于粗尾矿充填体,两者强度的差异主要受到细颗粒含量与颗粒接触状态两方面的影响。

In underground mining,the filling body is disturbed by dynamic loads such as blasting vibration,which seriously threatens its stability.In addition,the strength of the filling body will be further reduced after the use of ultra-fine tailings.Therefore,it is urgent to carry out research on the dynamic properties of ultra-fine tailings cemented filling body.Taking the ultra-fine tailings filling body and the coarse tailings filling body as the research object,the impact test under different strain rates was carried out by using the Hopkinson device,and the comparative analysis was carried out.The results show that compared with the coarse tailings filling body,the elastic stage of the ultra-fine tailings filling body is shorter.After entering the yield stage,the yield stage is longer because the internal pores are compressed to improve its strength and deformation resistance.The failure stage of the coarse tailings filling body shows the phenomenon of stress drop,and the ultrafine tailings filling body shows post-peak plasticity in the failure stage.The dynamic compressive strength of ultra-fine tailings filling body with similar average strain rate is much smaller than that of coarse tailings filling body.The dynamic compressive strength of ultrafine tailings filling body and coarse tailings filling body tends to be gentle after the average strain rate reaches about 60 s^(-1) and 80 s^(-1),respectively.With the increase of the average strain rate,the unit volume absorption energy of the ultra-fine tailings filling body increases continuously,and the unit volume absorption energy of the coarse tailings filling body increases significantly after the average strain rate exceeds 80 s^(-1).When the average strain rate is similar,the damage degree of the ultra-fine tailings filling body is significantly greater than that of the coarse tailings filling body.The difference in strength between the two is mainly affected by the content of fine particles and the contact state of particles.