纤维增强含硫尾砂胶结充填体的力学性能及能量分配演化特征

Mechanical properties and energy distribution evolution characteristics of fiber-reinforced cemented sulfur tailings backfill

开展纤维增强含硫尾砂胶结充填体的单轴压缩试验,研究纤维含量对充填体力学特性的影响规律,并揭示纤维增强含硫尾砂胶结充填体在峰值应力前的能量分配演化特征及损伤破坏演化过程。研究结果表明:添加聚丙烯纤维的充填体在荷载超过应力峰值后,应力-应变曲线并没有快速下降,说明纤维的掺入提高了充填体的抗变形破坏能力;充填体的轴向应力和轴向应变均随着纤维含量的增加呈先增大后减小的趋势,并且聚丙烯纤维提高残余应力的效果要明显高于提高峰值应力的效果;纤维增强含硫尾砂胶结充填体在峰值应力处的总应变能、弹性应变能及耗散能均表现为先增大后减小的趋势,并在纤维含量(质量分数)为0.6%时达到最大值;此外,当纤维含量为0~0.6%时,总应变能随着纤维含量的增加基本遵循一次函数递增规律,而弹性应变能及单位体积应变能随着纤维含量的增加均基本遵循指数函数递增规律;添加纤维的充填体损伤增长速率要明显低于未添加纤维的充填体损伤的增长速率,并且充填体在峰值应力前的损伤破坏过程主要经历了3个阶段。

The uniaxial compression test of fiber reinforced sulfur tailings cemented backfill was carried out in the laboratory. The influence of fiber content on the mechanical characteristics of backfill was studied, and the energy distribution evolution characteristics and damage evolution process of cemented backfill with fiber reinforced sulfur tailings before peak stress were revealed. The results show that the stress-strain curve of the backfill with polypropylene fiber does not decrease rapidly after the load exceeds the stress peak, indicating that the fiber addition improves the ability of the backfill to resist deformation and failure. The axial stress and axial strain of backfill firstly increase and then decrease with the increase of fiber content, and the effect of polypropylene fiber on increasing residual stress is obviously higher than that on increasing peak stress. The total strain energy, elastic strain energy and dissipative energy of cemented filling with sulfur tailings reinforced by fiber increase first and then decrease at the peak stress, and reach the maximum value when the fiber content is 0.6%. In addition, when the fiber content is 0-0.6%, the total strain energy increases with the increase of fiber content in a linear function,while the elastic strain energy and strain energy per unit volume increase with the increase of fiber content in an exponential function. The growth rate of the damage value of the backfill with fiber is significantly slower than that of the backfill without fiber, and the damage and failure process of the backfill before the peak stress mainly goes through three stages.