基于三维形貌的水工混凝土抗冲磨性能评价与预测

Evaluation and prediction on scouring-abrasion resistance of hydraulic concrete based on three-dimensional morphology

用机械探针测绘了水下钢球法试验中混凝土试件(水胶比分别为0.3、0.4、0.5)在不同冲磨时间(24~120 h)下的三维磨蚀形貌,并计算了磨蚀深度、磨蚀体积和分形维数,在此基础上,用投影寻踪回归(PPR)软件建立了考虑水胶比和冲磨时间的混凝土磨蚀损伤预测模型。结果表明:在水下钢球法试验条件下,混凝土表面形貌与冲磨时间及空间位置有关,可分为损伤区、过渡区和完好区;机械探针法能够较好地表征混凝土的冲磨时变行为;随着冲磨时间的延长,试件的磨蚀深度、磨蚀体积不断增大,分形维数增至2.60左右时逐渐趋于稳定;随着水胶比的增加,试件的磨蚀深度、磨蚀体积和分形维数均增大;建立的混凝土磨蚀损伤预测模型的计算精度较高,可为实际工程中水工混凝土的抗冲磨性能评价及寿命预测提供参考。

The three-dimensional abrasion morphology of concrete specimens with water-cement ratios of 0.3,0.4,and 0.5,respectively in underwater steel ball method tests was measured by using digital mechanical probe at different abrasion times(24~120 h),and the abrasion depth,abrasion volume,and fractal dimension were calculated.Based on this,a concrete abrasion damage prediction model considering water-cement ratio and abrasion time was established by using Projection Pursuit Regression(PPR)software.The results show that under the underwater steel ball method test conditions,the surface morphology of concrete is related to the abrasion time and position,and can be divided into abrade zone,transition zone,and intact zone.The digital mechanical probe method can better characterize the time-varying behavior of concrete abrasion.As the abrasion time prolongs,the abrasion depth and abrasion volume of the specimen continue to increase,and the fractal dimension gradually stabilizes when it reaches around 2.60.As the water-cement ratio increases,the abrasion depth,abrasion volume,and fractal dimension of the specimen all increase.The calculation accuracy of the established concrete abrasion damage prediction model is high,which can provide a reference for the evaluation of the scouring-abrasion resistance and life prediction of hydraulic concrete in practical engineering.