考虑分层特性的尾砂胶结充填体强度折减试验研究

Tests of strength reduction of cemented tailings filling considering layering character

充填体分层现象在分段或阶段嗣后填充采空区过程中较为常见。设置65％、70％、72％和75％4个浓度，填充次数为1、2、3和4制作不同分层胶结充填体试件，进行单轴压缩试验探究其力学强度及其破坏模式。试验结果表明：（1）相同浓度条件下，随着填充次数增多，胶结充填体的单轴抗压强度弱化效应越明显，而当浓度在65％～75％之间变化时，对应强度折减系数介于0．592～0．967；（2）充填体单轴抗压强度与填充次数之问满足二次多项式函数关系，而与料浆浓度呈对数函数分布；（3）不同分层胶结充填体的破坏模式主要表现为共轭剪切破坏和贯穿分层面的张拉破坏。低强度夹层可能是导致分层胶结充填体强度降低的原因，能够为后期填充采空区的充填体强度设计提供可靠的理论依据。

The layering phenomenon in filling is very common in the process of stepwise or subsequent backfilling. Different cemented filling specimens are prepared with four concentrations （65%, 70%, 72% and 75%） and backfilling times of l, 2, 3 and 4, separately. Uniaxial compression tests are conducted to study mechanical properties and failure modes of specimens. The research demonstrates that： （1） When the concentrations of different filling specimens are the same, the weakening effect of the uniaxial compressive strength （UCS） increases with increasing the filling time. When the concentrations vary from 65% to 75%, the corresponding strength reduction coefficients are in the range from 0.592 to 0.967. （2） The relationship between UCS of the specimen and the filling time fits the quadratic function, whereas the relationship between UCS and concentration fits the logarithmic function. （3） Main failure modes of different filling specimens are characterized by conjugated shear failure and tensile failure along the layer plane. Low-strength interlayer may result in decreasing the strength of layered cemented filling specimens, which can also be considered as theoretical reference for designing the strength of mine backfilling.