煤矿开采中岩体受开挖卸荷因素的影响常处于反复的循环加载过程，为研究循环梯度加载作用下煤岩的损伤破坏特性和能量演化规律，对煤样进行单轴循环梯度加载实验，对比分析煤岩在不同循环梯度加载下的变形破坏特性、输入能量密度、耗散能密度和损伤变量的规律。结果表明：随着循环梯度应力的递增，煤岩试样所承受的循环次数递减、峰值强度降低，分别为17.97、14.86、11.23、10.53 MPa；在循环梯度加载中，输入能量密度绝大部分以弹性应变能的形式储存于岩样内部，耗散能在单次循环输入总能量的0.2%～40%之间递增。选用累积耗散作为煤岩损伤破坏全过程的量化指标，并通过Logistic方程对煤岩损伤进行了拟合，得到了煤岩损伤的演化模型。

In coal mining, the rock mass is often in the process of repeated cyclic loading due to the influence of excavation and unloading factors. In order to study the damage and failure characteristics and energy evolution law of coal and rock under cyclic gradient loading, a uniaxial cyclic gradient loading experiment was carried out on coal samples, and deformation failure characteristics, input energy density, dissipated energy density and damage variables of the coal samples under different cyclic gradient loading were compared and analyzed. The results show that with the increase of the cyclic gradient stress, the number of cycles and the peak strength of the coal samples decrease, which are 17.97, 14.86, 11.23, and 10.53 MPa; in cyclic gradient loading, most of the input energy density is stored inside the rock sample in the form of elastic strain energy, and the dissipation energy increases between 0.2% and 40% of the total input energy in a single cycle. Cumulative dissipation is selected as the quantitative index of the whole process of coal and rock damage, and the Logistic equation is used to fit the coal and rock damage, and the evolution model of coal and rock damage is obtained.