中文摘要：

应用工业CT（Industrial Computer Tomography，ICT）对路面底基层（水泥稳定碎石层）材料单轴加载细观破裂全过程进行了观测，获得了试件内部裂纹开裂、发展及连通的全过程CT图像。给出了利用DR（Digital Radiography）及CT图像进行试件尺寸测量的方法，计算得到轴向应变及体积应变，获得了全程的应力应变曲线及体积应变曲线，根据曲线把试件变形分为弹性压缩、塑性变形和破坏扩容3个阶段。在弹性压缩阶段，试样各层CT图像灰度均值呈小幅增长趋势，在塑性变形阶段达到极大值后开始减小，在破坏扩容阶段，灰度均值急剧减小；各层CT图像的灰度值方差在弹性压缩及塑性阶段缓慢地呈线性增长，进入破坏扩容阶段，灰度方差迅速增加；把灰度均值极大值和体积应变极小值对应的应力24．81MPa（峰值的83．36％）作为试件裂纹扩展的应力阀值；由CT图像及重构的剖面图像可知，试件破坏时，裂隙不仅在砂浆中沿骨料边缘扩展，还会穿过骨料扩展，裂隙扩展主方向与加载方向平行。

英文摘要：

The whole meso-fracture process of pavement subbase material （cement stabilized gravel） under uniaxial compression is observed by using Industrial Computer Tomography（ICT）, and the CT images revealing initiation and development of cracks as well as the links among cracks are acquired. The method using DR （Digital Radiography） and CT image to measure the size of specimen is imposed. With this method, the axial strain and volume strain are calculated, and then the stress-strain curve and volume strain curve are obtained. With reference to the curve, the specimen deformation process is divided into three phases： elastic compression, plastic deformation and damage expansion. In elastic compression phase, the gray mean value of CT images has a small increase trend. In plastic deformation phase, the gray mean values get the maximum and then decrease. The gray mean values drop rapidly during damage expansion phase. The gray variances of CT images grow slowly in approximate linear both in elastic compression and plastic deformation phase, and increase dramatically during damage expansion phase. When the stress value is 24. 81 MPa （83. 36% of peak stress value）, the gray mean value and volume strain get their extreme value respectively, and the stress value is defined as the stress threshold of crack development. According to the CT images and reconstruction section images, the cracks not only develop in mortar along the edge of aggregates, but also cross the aggregates. The direction of crack development is parallel to the loading direction.