煤炭资源开采过程中，半煤岩巷掘进和薄煤层回采都不可避免地会使煤岩组合系统发生自由面卸荷。自由面卸荷现象往往伴随着能量的快速积聚与释放，所以探究煤岩组合体试样卸围压条件下的能量演化规律十分必要。为此，针对煤岩组合体试样开展了不同卸荷速率的卸围压试验。结果表明：（1）轴向加载阶段和应力恒定阶段为组合体试样的主要储能阶段，失稳破坏阶段主要以能量的释放和耗散为主；（2）卸荷速率加快会导致试样峰值弹性能降低，0.03MPa/s时峰值弹性能分别为0.06、0.09、0.12MPa/s时的1.64、2.70、3.50倍；（3）卸荷速率加快会导致试样峰后耗散能的增加，0.03、0.06、0.09、0.12MPa/s卸荷速率下，峰后耗散能量分别为峰值弹性能的28.17%、49.53%、69.55%、92.87%；（4）卸荷速率的增大会显著增强煤岩组合体试样的拉伸破坏趋势，导致断裂角增大、拉伸次生裂纹增多和破坏强度增强；（5）建立考虑初始损伤的耗散能本构模型，合理阐释了卸围压条件下煤岩组合体试样损伤演化全过程。该研究成果对于了解卸围压速率对煤岩组合体试样的能量演化特征具有重要意义。 In coal mining

the excavationof a coal-rock roadway and a thin coal seam will inevitably cause radialunloading of the coal-rock combination system. The radial unloading phenomenonis often accompanied by the rapid accumulation and release of energy

so it isnecessary to investigate the energy evolution law of coal-rock combinationspecimens under the unloading confining pressure condition. To this end

theunloading confining pressure tests with different unloading rates were carriedout for the coal-rock combination specimens. The results show that: (1) The axialloading and constant stress stages are the main energy storage stages of the combinationspecimens. The failure stage is mainly dominated by the release and dissipationof energy. (2) The acceleration of the unloading rate leads to the decrease ofthe peak elastic energy of the specimens

and the increment of the elasticenergy at 0.03 MPa/s in the constant stress stage is 1.64

2.70 and 3.50 timesof that at 0.06 MPa/s

0.09 MPa/s

and 0.12 MPa/s

respectively. (3) The increaseof unloading rate will lead to the increase of post-peak dissipation energy ofthe specimen

and the post-peak dissipation energy is 28.17%

49.53%

69.55%and 92.87% of the peak elastic energy when the unloading rate increases from 0.03MPa/s to 0.12 MPa/s

respectively. (4) The increase in unloading rate willsignificantly enhance the tensile failure tendency of coal-rock combinationspecimens

resulting in an increase in the fracture angle

an increase in thenumber of tensile secondary cracks

and an enhancement in the breaking strength.(5) A dissipative energy constitutive model considering the initial damage isestablished to reasonably explain the whole process of damage evolution ofcoal-rock combination specimens under the unloading confining pressureconditions. The research results are significant forunderstanding the energy evolution characteristics of coal-rock combination samples with unloadingrate.