单轴压缩下不同养护龄期尾砂胶结充填体损伤特性及能量耗散分析

Analysis of damage characteristics and energy dissipation of cemented tailings backfill with different curing ages under uniaxial compression

为了研究养护龄期对尾砂胶结充填体损伤特性及能量耗散的影响,在RMT-150C岩石力学试验系统上对不同养护龄期下尾砂胶结充填体进行单轴压缩试验。研究结果表明:养护龄期的延长能够有效阻碍试件裂纹的萌生与扩展,抑制试件内部能量的扩散,使线弹性变形阶段能够延伸到更高的水平,从而提高了充填体抗压强度;充填体的峰前能耗量、峰后能耗量、单位体积应变能及总能耗量与养护龄期呈指数函数曲线关系;充填体峰前和峰后的能量耗散速率与养护龄期具有良好的指数正相关性,充填体的峰后能量耗散速率显著大于峰前能量耗散速率,说明峰前损伤较慢,而峰后则快速损伤破裂,耗散能曲线突然变陡意味着充填体开始破坏;在养护早期,充填体的峰前能耗量和总能耗量随轴向应变增大其增幅较低,总能耗与轴向应变呈指数函数曲线关系;充填体的峰值应力损伤与养护龄期具有良好的指数正相关性;单轴加载下充填体受压破坏的能量损伤演化机制可划分为初始损伤、损伤稳定发展、损伤加速及损伤破坏4个阶段。

In order to study the influence of curing age on the damage characteristics and energy dissipation of cemented tailings backfill, a uniaxial compression test was carried out on the cemented tailings backfill with different curing ages on the RMT-150 C rock mechanics test system. The results show that the prolongation of curing age can effectively hinder the initiation and expansion of cracks in the specimen, and inhibit the diffusion of energy inside the specimen to make the elastic deformation stage reach a high level, and thereby improve the compressive strength of the backfill. The energy consumption of the backfill in different uniaxial compression stages is basically the same as that in the curing age, and follows the exponential function growth law. With the longer curing age, the strain energy and energy storage limit required for the deformation and failure of the filling body increase, which follows the exponential function curve growth law. The energy dissipation rates before and after the peak of the filling body have a good exponential positive correlation with the curing age. The post-peak energy dissipation rate of the backfill is significantly larger than the pre-peak energy dissipation rate, which indicates that the damage before the peak is slow, and the damage after the peak is broken, showing that the sudden dissipation of the dissipation energy curve means that the backfill begins to break. The energy consumption value of the backfill generally follows the exponential curve growth rule with the increase of strain, and the energy consumption is smaller before the peak of the backfill as the curing age is shorter. The peak stress damage of the filling body has a good exponential positive correlation with the curing age. Based on the evolution law of damage and energy consumption, the energy damage evolution process of the backfill under uniaxial loading can be divided into four stages: initial damage, stable development of damage, acceleration of damage and damage failure.