<p>Underground mining in deep, high-stress environments is a progressive process, where successive stages of ore extraction and backfilling result in increasing rockmass-induced closure strains on the backfill, along with concurrently increasing backfill pressures acting against the rockmass. Quantifying this rockmass-backfill interaction requires, in part, a better understanding of the backfill’s mechanical properties under different load paths. Previous work by the authors on a particular mine’s Cemented Paste Backfill (CPB) showed that the material exhibits nonlinear behavior in both one-dimensional and isotropic stress–strain responses, and which can be characterized in three phases: initial elastic, transitional, and post-yield compression. For design purposes, this nonlinearity can be simplified as a bilinear response in e-log(p’) space with the breakpoint at a characteristic load, <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="603_2025_4595_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="35" /> </InlineMediaObject> <EquationSource Format="TEX">${P}_{Oed}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>P</mi> <mrow> <mi mathvariant="italic">Oed</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>. The current work extends the previous one-dimensional framework to consider a wider variety of materials (six different backfills from three new mines) and a broader range of backfill densities, including those blended with sands, as well as backfills with very low initial water contents (e.g., filter cake, which is too dense to be transported by pipeline). In addition, a method was developed to predict the nonlinear behavior described in the previously suggested generalization of CPB’s one-dimensional response, allowing for a more accurate quantification of a mine’s backfill response to surrounding rock wall closure. The generalized response (both nonlinear and simplified bilinear) for non-plastic CPBs has significant design implications for underground mining engineering, as the developed constitutive models allow field measurements of backfill closure strains and induced stresses to be quantitatively interpreted, enhancing the understanding of how the surrounding rockmass responds to ongoing mining activities. In this sense, the backfill effectively acts as a “large-scale calibrated stress cell” to quantify rockmass behavior during mining.</p>

Development of a Method to Predict the Nonlinear Mechanical Response of Cemented Paste Backfill to Mining Induced Closure Strains

期刊论文
发表日期：

2025年5月9日

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Mohammadamin Jafari,
Xuepeng Song,
Murray Grabinsky

摘要

Underground mining in deep, high-stress environments is a progressive process, where successive stages of ore extraction and backfilling result in increasing rockmass-induced closure strains on the backfill, along with concurrently increasing backfill pressures acting against the rockmass. Quantifying this rockmass-backfill interaction requires, in part, a better understanding of the backfill’s mechanical properties under different load paths. Previous work by the authors on a particular mine’s Cemented Paste Backfill (CPB) showed that the material exhibits nonlinear behavior in both one-dimensional and isotropic stress–strain responses, and which can be characterized in three phases: initial elastic, transitional, and post-yield compression. For design purposes, this nonlinearity can be simplified as a bilinear response in e-log(p’) space with the breakpoint at a characteristic load, ${P}_{Oed}$ $P_{Oed}$ . The current work extends the previous one-dimensional framework to consider a wider variety of materials (six different backfills from three new mines) and a broader range of backfill densities, including those blended with sands, as well as backfills with very low initial water contents (e.g., filter cake, which is too dense to be transported by pipeline). In addition, a method was developed to predict the nonlinear behavior described in the previously suggested generalization of CPB’s one-dimensional response, allowing for a more accurate quantification of a mine’s backfill response to surrounding rock wall closure. The generalized response (both nonlinear and simplified bilinear) for non-plastic CPBs has significant design implications for underground mining engineering, as the developed constitutive models allow field measurements of backfill closure strains and induced stresses to be quantitatively interpreted, enhancing the understanding of how the surrounding rockmass responds to ongoing mining activities. In this sense, the backfill effectively acts as a “large-scale calibrated stress cell” to quantify rockmass behavior during mining.