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采用分级加载方式对一种红砂岩试件进行单轴压缩蠕变试验,通过Charge-Coupled De-vice(CCD)相机采集加载全过程的试件表面散斑图像,以白光数字散斑相关方法(DSCM)对分级加载不同阶段试件表面变形场演化及裂隙位移演化进行观测和分析.结果表明:在分级加载过程中,试件的瞬时变形量随着载荷的增加而减小,蠕变变形量随着载荷的增加而增加;低应力水平,试件处于均匀变形状态,不发生蠕变或蠕变量较小;中等应力水平,裂隙产生及裂隙在整个恒载期间未发生蠕变扩展的变形累积阶段;高应力水平,裂隙在恒载初期的变形累积到恒载后期的裂隙稳定蠕变扩展,最终加速蠕变扩展;当岩石试件变形出现裂隙区域后,裂隙的位移错动和位移拉伸直接影响了岩石蠕变位移特征.裂隙的位移错动速率包括减速错动、稳定错动和加速错动3种形式.
Uniaxial compressive creep test on a red sandstone specimen was carried out by graded loading. Speckle images on the whole surface of specimen were collected by Charge-Coupled De-vice (CCD) camera and analyzed by white digital speckle correlation method DSCM) were used to observe and analyze the evolution of surface deformation field and the evolution of fracture displacement in different stages of the stage loading.The results show that during the stage loading, the instantaneous deformation of specimen decreases with the increase of load, and the creep deformation With the increase of load; low stress level, specimen in a uniform deformation state, no creep or a small amount of creep; medium stress level, crack generation and crack creep expansion during the entire load without deformation Accumulation stage; high stress level, the crack in the initial stage of permanent load deformation accumulated to the late stable crack creep expansion, and finally accelerate the creep expansion; when the deformation of the rock specimens appear fracture area, the fracture displacement and displacement displacement Extension directly affects the creep displacement characteristics of the rock.The displacement dislocation rate of the fractures includes three forms of deceleration dislocation, steady dislocation and acceleration dislocation.