深部地热与矿床流变协同作用下的尾矿胶结充填体孔隙水压响应研究

Pore Pressure Response of Cemented Mine Backfill under Geothermal and Rheological Loading of Deep Ore Deposit

在不断提高的安全生产标准和环境保护压力推动下,尾矿的地下处置逐渐成为实现矿产资源绿色清洁开采的重要途径。然而随着浅埋矿产资源日益枯竭,矿山开采不断向地球深部发展,因此尾矿充填技术将面临极端温度环境和矿床流变特性的严峻挑战。本研究基于孔隙热弹性理论框架建立蠕变加载条件下的尾矿胶结充填体非等温孔隙水压演化模型,进而计算分析不同初始温度的充填体单元在持续热量交换和围岩蠕变变形协同作用下的孔隙水压演化规律。计算结果表明,虽然水泥水化过程会消耗自由水进而促进水压耗散,但水化反应放热与高温岩体传热共同造成的水热增压效应以及采场围岩蠕变造成的体积压缩作用也将导致持续的压力增长,因此充填体孔隙水压的演化规律将最终取决于以上耗散与增长机制之间的相互竞争效应。具体而言,对于本研究的充填体配比,40℃条件下的水化反应不会造成显著的水压变化;同时,虽然快速的岩体变形速率恒为充填体水压发展的控制性因素,但30℃初始温度条件下的充填体降温过程则将抵消低速蠕变(1×10^(-10)s^(-1))造成的水压增长,研究成果对揭示深部开采条件下的充填体多物理场响应机理,进而实现深部矿山安全清洁生产具有重要的理论和工程意义。

Underground disposal of tailings has gradually become an important pathway to achieving green and clean mining of mineral resources driven by the ever-improving safety production standards and environmental protection regulations.However,mine production continues to develop deeper into the earth as the shallow buried mineral resources deplete,and the minefill technology will thus face severe challenges from the extreme temperature environment and rheological characteristics of the deep strata.In this study,a non-isothermal pore pressure evolution model for backfill element under creep loading is developed by extending theoretical framework of poro-thermoelasticity,and the pore pressure evolution of the backfill element under the synergistic effect of heat exchange and creep deformation is then analyzed.The results show that the hydration process will consume pore water and thus promote pressure dissipation,but the thermal pressurization effect caused by exothermic hydration and heat transfer as well as the continuous compression caused by rock creeping will also lead to significant pressure build-up.Therefore,the evolution of pore pressure will ultimately depend on the competitive tradeoff between the above dissipation and generative mechanisms.Specifically,regarding the backfill mix studied herein,the hydration reaction at 40℃may not result in significant pressure changes.Meanwhile,although rapid rock deformation remains a controlling factor in pressure generation,the cooling of warm backfill could still potentially offset the pressure increase caused by slow creep loading(1×10^(-10)s^(-1)).The research findings have theoretical and engineering significance for revealing the behavioural mechanism of backfill under the combined action of heat exchange and creep loading,thus realizing safe and clean production of deep mines.