高强混凝土裂纹扩展规律的CT观察

MECHANICS OF CRACK PROPAGATION IN HIGH PERFORMANCE CONCRETE AND ITS FRACTAL DIMENSIONS BASED ON CT OBSERVATION

随着我国煤矿开采深度的不断加大,对深厚表土层立井井壁所使用的高性能混凝土的强度、耐久性等性质的要求也越来越高。基于工业CT测试技术,对深厚表土层立井使用的C100高性能混凝土试样进行了细观力学试验,分析了在单轴压缩条件下其内部微裂纹的孕育、萌生、发展及其贯通过程。并利用盒维数法,计算了其内部微裂纹演化的分形维数,在此基础上,获得了载荷、裂纹扩展及分形维数三者之间的对应关系。结果表明:C100高性能混凝土胶凝材料具有较高的强度;随着加载应力的提高,混凝土的破碎程度加深,裂纹的弯折程度加大,导致裂纹演化的分形维数也增大。

With the increasing depth of coal mining in China,there is an immediate need to improve the strength and durability of high performance concrete used in deep topsoil mine shafts.Based on computer tomography（CT）,the micro-mechanical behavior of C100 high-performance concrete samples used in the shaft of deep topsoil was investigated,and the courses of the origination and development of cracks and links were analyzed under uniaxial compression.Using the box-counting dimension method,the surface fractal dimensions of its cracks were calculated.On the basis of the results,the relationship among the stress load,the crack development and the fractal dimensions was found.The test results show that the C100 high-performance concrete has high intensity;and with the increase of the stress load,the breakage of concrete deepens,and the degree of bending increases,so the surface fractal dimension of the crack also increases.