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不同养护温度下水泥基尾砂胶结充填体的力学特性及能量演化规律

Mechanical properties and energy evolution of cemented tailings backfill at different curing temperatures

  • 摘要: 养护温度能够对水泥基尾砂胶结充填体力学性能造成显著影响,在实验室开展了不同养护温度下的充填体单轴抗压试验,研究了养护温度对充填体应力-应变曲线及力学特性的影响规律,并揭示了充填体变形破坏各阶段的能量演化规律。结果表明:当养护温度范围为20~50 ℃时,充填体的峰值应力、初裂应力及弹性模量均随着养护温度的增加呈现先增大后减小的趋势,并且都在养护温度为30 ℃时达到最大值,说明充填体的养护温度存在临界值;充填体在峰值应力点处的总应变能及弹性应变能随着养护温度的增加均表现出先增大后减小的趋势,并且耗散能与总应变能随着轴向应变的增加呈现非线性递增规律;此外,在初始压密、线弹性变形及屈服破坏阶段,能量主要以弹性能的形式储存在充填体内部,而在峰后变形破坏阶段能量以耗散为主,并且养护温度会对能量指标水平产生影响;微观测试结果表明,充填体在高温养护环境下产生的自由水蒸发效应会导致充填体内部空隙结构更为明显,从而对充填体力学性能产生不利影响。

     

    Abstract: The mechanical properties of cement-based tailings cemented backfill can be significantly influenced by the curing temperature. Uniaxial compression tests were conducted in the laboratory on backfill samples cured at different temperatures to investigate the influence of curing temperature on the stress-strain curve and mechanical properties of the backfill. Additionally,the energy evolution law at each stage of backfill deformation and failure was studied. The results demonstrate that as the curing temperature increases from 20℃ to 50℃,the peak stress,initial crack stress,and elastic modulus of the backfill exhibit a first-increasing and then decreasing trend,reaching a maximum value at 30℃,indicating the existence of a critical value. Moreover,the total strain energy and elastic strain energy of the backfill at the peak stress point also follow a similar trend,with dissipated energy and total strain energy exhibiting a nonlinear increasing relationship with axial strain. Notably,in the initial compaction,linear elastic deformation,and yield failure stages,the energy is mainly stored in the form of elastic energy inside the backfill,while it is primarily dissipated in the post-peak deformation and failure stage. The curing temperature can affect the energy index level. Microscopic testing results indicate that the free water evaporation effect of the backfill in a high-temperature curing environment leads to a more apparent internal void structure of the backfill,which negatively affects its mechanical performance.

     

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