中文摘要：

为探讨泥岩在遇水–风干循环作用下断裂的微观机制,采用粉晶X射线衍射、力学性能测试和激光共聚焦显微镜等手段对泥岩进行表征,得到泥岩遇水后的成分变化、强度特征和遇水–风干循环作用下泥岩三维形貌的变化规律,分析泥岩在遇水–风干循环作用下断裂的微观机制。结果表明：泥岩遇水后部分钾长石变为高岭石;单轴抗压强度从5.31 MPa降为0 MPa;试样表面的裂纹数目、宽度随遇水–风干次数的增加而增加;伊利石黏粒遇水后水分子进入黏粒晶胞之间,引起晶格膨胀;黏粒表面吸附的水膜导致黏粒间距增加;泥岩遇水过程中在水的物理、化学作用下内部产生大量次生孔隙并且体积膨胀;风干过程中泥岩表层风干速度大于内部风干速度,表层局部黏粒富集区域体积收缩产生裂纹,随着遇水–风干循环次数的增加,泥岩内部裂纹的数量和尺寸逐渐增加,当裂纹贯穿试样时试样断裂。

英文摘要：

By X-ray diffraction,mechanical experiments of mudstone and three-dimensional laser topography measurement instrument, the mudstone was characterized to investigate the micro-fracture mechanism of mudstone after wet-dry cycles. A series of data were obtained,such as composition,mechanical strength,topography of mudstone in the process of wet-dry cycles. More attention was paid to the micro-fracture mechanism of mudstone in wet-dry cycles. Results show that：Some microcline generates kaolinite after dry mudstone becoming wet. The uniaxial compressive strength of dry mudstone is 5.31 MPa,and it decreases to 0 MPa when the mudstone is put into water. With the increase of the number of wet-dry cycles,the quantity and width of cracks increase. Water molecules enter the space between unit cells of illite clay grains and water films form on the surface of clay grains,when the mudstone is wet. Some second porosity generates because of the physical and chemical effects of water when mudstone becomes wet,and the volume of mudstone becomes large also. Some cracks form in localized surface areas enriching clay grains of mudstone due to the different contraction velocities between surface and inner. The quantities and size of cracks increase upon the increase of the times of wet-dry cycles. The sample fractures when the cracks penetrate the whole sample.