Aquathermal effect of anomalous pressure generation in consolidating minefill

G. D. Lu, A. P. S. Selvadurai, M. Meguid
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Abstract

Recycling cement-amended tailings into subsurface cavities has delivered competitive socioeconomic revenue for underground mining. However, recent instances of anomalous thermal pressure in consolidating backfill have raised growing concerns over the current design philosophy. This study demonstrates that the excellent hydraulic sealing and considerable chemical energy inherent in cemented backfill can spontaneously generate substantial thermal pressurization through constrained pore-fluid expansion. An analytical solution is hence developed for characterizing the non-isothermal behaviour of hydrating backfill based on classical thermo-poroelasticity. The influence of preparation condition and mix design on the pressure evolution in time domain and during spontaneous heat generation is then thoroughly examined, successfully pinpointing the causal mechanism responsible for typical thermal pressure anomalies. It is demonstrated that the anomalous pressure is attributable to both the conservative binder usage, which increases the intrinsic heat load, and the elevated initial temperature, which promotes water volume expansion. The fundamental influence of temperature-sensitive water expansivity on the path dependence of thermal pressurization is also elucidated. This study thus contributes to a comprehensive understanding of the thermally correlated pressure anomalies that frequently occur in field operations. These critical findings would also hold practical implications for designing successful backfill solutions in challenging mine environments.
固结矿床异常压力产生的水热效应
将经水泥拌和的尾矿回收利用到地下矿洞中,为地下采矿带来了有竞争力的社会经济收入。然而,最近在固结回填中出现的异常热压现象,使人们对当前的设计理念越来越担忧。本研究表明,固结回填土固有的出色水力密封性和可观的化学能可通过受限孔隙流体膨胀自发产生大量热压。因此,基于经典的热弹性,开发了一种分析解决方案,用于描述水化回填土的非等温行为。然后深入研究了制备条件和混合设计对时域和自发热过程中压力演变的影响,成功地找出了典型热压异常的成因机制。结果表明,异常压力可归因于增加固有热负荷的保守粘结剂用量和促进水体积膨胀的较高初始温度。此外,还阐明了对温度敏感的水膨胀性对热加压路径依赖性的根本影响。因此,这项研究有助于全面了解野外作业中经常出现的热相关压力异常。这些重要发现还将对在具有挑战性的矿山环境中设计成功的回填解决方案产生实际影响。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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