To elucidate the mechanical response mechanisms and the deformation and failure characteristics of layered cemented backfill under the influence of complex interlayer parameters, this study investigates the stage subsequent filling method employed in an iron mine. The research systematically examines the effects of stratification angle, cement-sand ratio, and intermediate layer height on the mechanical properties and damage evolution of backfill through comprehensive uniaxial compression tests. The findings indicate that both the uniaxial compressive strength and the elastic modulus of the backfill decrease with an increase in stratification angle, a decrease in cement-sand ratio, and an increase in intermediate layer height. The sensitivity of these factors to strength is ranked as follows: cement-sand ratio>intermediate layer height>stratification angle. Further analysis reveals that the relationship between these three factors and compressive strength adheres to a logarithmic function. The multivariate nonlinear regression prediction model developed in this study demonstrates high accuracy and serves as a quantitative tool for predicting strength. Analysis of the stress-strain curve indicates that the layered structure results in the characteristic four-stage deformation behavior of the filling body. As the layer angle increases, the cement-sand ratio decreases, or the height of the middle layer increases, the post-peak ductile deformation capacity of the filling body diminishes, rendering the failure process more brittle. This study elucidates the mechanical weakening mechanism of the layered filling body. The findings provide theoretical guidance for optimizing the design parameters of interlayers in the filling body, predicting its macroscopic mechanical behavior, and managing the stability of the stope.
在分层充填体研究领域,国内外学者已取得一系列重要成果。部分研究侧重于单一因素或特定工况下分层充填体的力学响应与破坏模式。例如:在材料与结构参数方面,通过试验系统分析了灰砂比和高度比等关键变量对充填体力学行为、裂纹演化及声发射特征的影响,并据此建立了相应的损伤本构模型(曹帅等,2016;唐亚男等,2020;Wang et al,2021)。也有研究聚焦于层间界面的控制作用,揭示了不同界面特征对整体力学性能的影响规律,发展了能够综合考虑分层效应的本构模型(汪杰等,2019;海龙等,2023)。此外,探讨了冲击荷载和养护温度等特殊环境下分层充填体的性能响应(Sun et al,2022;周平锋等,2022)。这些研究共同构成了从内在材料结构、关键界面特性到外部环境因素的多尺度研究框架。通过系统梳理现有文献发现,当前研究仍存在以下不足:研究因素相对孤立,多数研究侧重于考察单一因素(如灰砂比或层高)或固定角度(尤其是水平分层)的影响,而对于多个关键层间参数(如灰砂比、中间层高度和分层角度)同时变化时的耦合影响机制缺乏系统研究;非线性定量关系揭示不足,尽管已知这些因素会影响充填体强度,但对于它们与宏观力学性能(如单轴抗压强度)之间可能存在的复杂非线性定量关系,目前尚缺乏深入研究和精确的数学表征;预测模型有待完善,现有模型多集中于本构关系的理论描述,能够同时集成上述三因素并用于精确预测分层充填体强度的实用化回归模型仍较为欠缺。
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