考虑空隙非线性变形的胶结充填体损伤软化本构模型研究

Damage Softening Constitutive Model of Cemented Backfill Considering Nonlinear Deformation of Void

充填采矿法在两步骤回采方式中广泛应用,胶结充填体作为人工矿柱,其稳定性至关重要;而胶结充填体力学特性及本构模型是进行稳定性分析与评价的重要内容,因此,亟需开展胶结充填体力学特性及本构模型研究。通过对不同灰砂比的胶结充填体进行单轴压缩试验,试验结果表明:在初始压密阶段因空隙存在而表现出非线性变形特征;在塑性屈服阶段及破坏后阶段刚度和强度均表现出软化特性;破坏后阶段存在较强的承载特性。针对试验结果,采用宏观和细观相结合的方法,将胶结充填体抽象成空隙和细观单元2部分,并引入胶结充填体有效损伤因子,结合统计损伤理论,分别构建空隙本构方程和细观单元损伤软化本构方程,进而得到胶结充填体损伤软化本构模型。最后将本研究理论模型曲线与试验曲线、现有理论基于试验数据和其他学者试验数据得到的曲线进行对比分析,分析结果表明本研究得到的理论曲线与试验曲线有较高的匹配度,各阶段曲线拟合相关系数都达到95%以上,更好地表征了胶结充填体空隙非线性变形特征及软化特性。研究结果可为胶结充填体稳定性分析提供理论依据。

Filling mining method has been widely used in the two-step mining method.The cemented filling body is an artificial pillar,so its stability is very important.However,the mechanical properties and constitutive model of the cemented filling body are the important contents of the stability analysis and evaluation.Therefore,It is urgent to study the mechanics characteristics and constitutive model of cemented filling body.In this article,the uniaxial compression tests were carried out on cemented filling bodies with different ratios of ash and sand.The results show that:nonlinear characteristics of the cemented filling body are shown due to the existence of voids in the initial compacting stage;the stiffness and the strength in the plastic yielding and post-both appear softening properties;and there exists strong bearing property in the post-destructive stage.According to the test results,a combination of macro and microscopic method is adopted to abstract the cemented filling body into two parts of voids and macro units,and the effective damage factor of cemented filling body is introduced to build the voids constitutive equation and the units damage softening constitutive equation by combining with statistical damage theory,and then the damage softening constitutive model of cemented filling body is obtained.Finally,the theoretical model curve is compared with the experimental curve and the existing theory based on the experimental data and other scholars'experimental data.The analysis results show that the theoretical curve is highly consistent with the test curve,and the correlation coefficients of the curve fitting in all stages are above 95%,which better characterize the non-linear deformation and softening characteristics of the cemented filling body void.The results provide a theoretical basis for the stability analysis of cemented filling body.