为了探究岩石单轴蠕变的应变能密度演化规律及其损伤本构模型, 利用单轴蠕变−卸载试验, 系统性地研究了煤、泥岩、白砂岩和红砂岩4种岩石的蠕变应变能密度演化规律。着重探讨了岩石在蠕变过程中应变能密度的转化与耗散机制, 建立了不同脆性程度岩石的损伤蠕变本构模型。研究结果表明: (1) 4种岩石的弹性应变能密度随蠕变时间的延长而呈线性减少的趋势, 即存在线性衰减特征; (2)结合单轴蠕变−卸载试验结果, 提出了一种基于弹性应变能密度线性衰减特征的岩石蠕变应变能计算方法; (3) 4种不同脆性程度的岩石蠕变产生的耗散应变能密度与输入应变能密度随着时间增加而增长, 其增长可分为衰减增长阶段、匀速增长阶段以及加速增长阶段; (4)在蠕变过程中, 随着蠕变时间的增加, 岩石耗散应变能密度占输入应变能密度逐渐增大, 在加速蠕变与峰后的临界点达到最大, 脆性程度越高加速蠕变与峰后临界点耗散应变能密度占输入应变能密度比例越大; (5)构建了基于应变能耗散的黏弹塑性−损伤耦合本构模型, 该模型能够有效描述不同脆性岩石在蠕变过程中的变形曲线。

To investigate the principles governing the evolution of strain energy density and develop related damage constitutive models during uniaxial rock creep, uniaxial creep-unloading experiments was performed to systematically examine the creep strain energy density evolution of coal, mudstone, white sandstone and red sandstone. The focus is on exploring the conversion and dissipation mechanisms of strain energy density during rock creep and developing damage creep constitutive models for rocks of varying brittleness. The results show that the elastic strain energy densities of the four types of rocks show a linear reduction trend with extended creep time, displaying linear decay properties. Further, a method for calculating rock creep strain energy was proposed based on the linear decay properties of elastic strain energy density. The dissipative strain energy density, along with the input strain energy density for rocks categorized by four grades of brittleness, increases over time and can be divided into stages of decay growth, uniform growth, and accelerated growth. As creep time advances, the ratio of dissipative strain energy to input strain energy density in rocks increases, reaching the peak at the critical post-peak point during accelerated creep, where more brittle rocks show a larger proportion of dissipative strain energy density relative to input strain energy density. A viscoelastic-plastic-damage coupled constitutive model has been developed based on the dissipation mechanism of strain energy, effectively describing the behavior of rocks with varying brittleness along the creep curve.