不同氯离子质量分数下充填体变形破坏及能耗特征

Deformation failure and energy consumption characteristics of filling body at different mass fraction of chloride ions

为研究氯离子质量分数对充填体的变形、破坏和能耗损伤的影响,开展不同氯离子质量分数下充填体的单轴压缩试验和电镜扫描试验,分析充填体变形破坏和微观结构,并揭示试样在单轴压缩不同阶段时的能量分配演化规律及单轴受压破坏的能量损伤演化过程。研究结果表明:当氯离子质量分数不大于2%时,峰值强度和弹性模量随氯离子质量分数增加逐渐增加,当含氯离子质量分数为2%~4%时,峰值强度和弹性模量逐渐降低;当氯离子质量分数为2%时,内部结构最密实,孔隙率最小;当氯离子质量分数为4%时,有明显张裂带产生,孔隙率增加;当氯离子质量分数为0时,裂纹破坏主要为Ⅱ型贯穿剪切破坏,当氯离子质量分数为1%~3%时,裂纹主要以Ⅰ型半贯穿张拉破坏为主,当氯离子质量分数为4%时,裂纹呈现Ⅰ-Ⅱ型张拉-剪切混合破坏模式;随着氯离子质量分数增加,峰前能耗、破坏时单位体积应变能、弹性应变能和总能耗在不同压缩阶段呈先增加后减小的变化趋势;不同氯离子质量分数充填体损伤D增长规律与能耗Ue增长规律相一致,据此将充填体能量损伤演化过程划分为初始损伤、损伤稳定发展、损伤加速和损伤破坏4个阶段。

In order to study the influence of chloride ion mass fraction on deformation,failure and energy consumption damage of backfill,uniaxial compression tests and scanning electron microscopy tests of backfill at different chloride ion mass fraction were carried out.The deformation,failure and microstructure of backfill were studied,and the evolution law of energy distribution of samples at different stages of uniaxial compression and the evolution process of energy damage in uniaxial compression failure were revealed.The results show that the peak strength and elastic modulus increase with the increase of chloride ion mass fraction when it is less than 2%,while the peak strength and elastic modulus decrease when the increase of chloride ion mass fraction is between 2%and 4%.When the mass fraction of chloride ions is 2%,the internal structure is the most dense and the porosity is the least.When the mass fraction of chloride ions is 4%,there is obvious crack zone and the porosity increases.When the chloride ion mass fraction is 0,the crack failure is mainly typeⅡthrough shear failure.When the chloride ion mass fraction is between 1%and 3%,the crack is mainly typeⅠsemi-through tensile failure.When the chloride ion mass fraction is 4%,the crack presents a mixed failure mode of type I-II tensile shear failure.With the increase of chloride ion mass fraction,the pre-peak energy consumption,unit volume strain energy,elastic strain energy and total energy consumption increase first and then decrease at different compression stages.The growth law of damage D of filling body with different chloride ion mass fraction is consistent with the growth law of energy consumption Ue.Therefore,the damage evolution process of filling energy volume can be divided into four stages,i.e.,initial damage,damage stable development,damage acceleration and damage destruction.