连续级配高强胶结充填体力学特性及破坏特征分析

Analysis of the mechanical properties and damage characteristics of continuously graded high-strength cemented backfill

充填开采技术不仅采出率高,而且能有效防止地表沉陷,维持采场稳定性,因此研究充填体受载时的力学特性与破坏特征具有一定的工程指导意义。开展了不同骨料粒径分布胶结充填体的单轴压缩试验和声发射监测试验,获得了粒径分布对充填体力学特性、声发射特征参数的影响规律及破坏特征。研究结果表明:随着泰波(Talbot)指数n的增大,胶结充填体的单轴抗压强度、弹性模量均呈先增大后减小的趋势,与峰值应变的变化规律相反。通过拟合分析得到充填体单轴抗压强度与Talbot指数n呈二次多项式关系,Talbot指数n在(0.4~0.5)间抗压强度达到最优。任意Talbot指数下,充填体在加载过程中声发射计数和能量均经历3个阶段:声发射平静期、低幅增长期和高幅增长期;充填体裂纹起裂应力和损伤应力随着Talbot指数的增大呈先增加后减小的趋势;裂纹起裂应力为峰值应力的31%~45%,损伤应力为峰值应力的74%~96%,两应力与峰值应力比值随Talbot指数无显著规律性变化,受自身性质影响较大。从宏、细观角度分析不同Talbot指数的胶结充填体的破坏模式,发现两者特征基本一致;不同骨料粒径的充填体试样的内部孔隙、裂隙等微观结构数目、排列不一,其破坏形式也不同。

The filling mining technology not only has a high recovery rate,but also can effectively prevent surface subsidence and maintain the stability of the quarry,so it is of certain engineering guidance to study the mechanical properties and damage characteristics of the filling body.In this paper,uniaxial compression tests and acoustic emission monitoring tests were carried out on cemented fillers with different aggregate size distributions.Through theoretical analysis of the test results,the influence of the number of particle size distributions on the physical properties of the filler and acoustic emission characteristics parameters and damage characteristics were obtained.The results show that the uniaxial compressive strength and modulus of elasticity of the filling body increase and then decrease with the increase of Talbot index n,which is opposite to the change of peak strain of the filling body.The uniaxial compressive strength and Talbot indices n are quadratic polynomially related,and the compressive strength is optimal between(0.4-0.5)for Talbot index n.Under any Talbot index,the AE counts and energy during loading of the filled body at arbitrary Talbot indices have roughly gone through three stages:the acoustic emission calm period,the low-amplitude growth period,and the high-amplitude growth period;the crack initiation and damage stress of the filled body tend to increase and then decrease with the Talbot index;the crack initiation stress is about 31%-45%of the peak stress,and the damage stress is about 74%-96%of the peak stress.The two ratios do not change regularly with the Talbot index,and are greatly affected by their properties.The damage patterns of cemented fillers with different Talbot indices were analyzed from the macroscopic point of view,and the characteristics of both were the same;the damage forms were different due to the different number and arrangement of internal pores and fissures and other microstructures of the filler specimens with different aggregate grain sizes.