某水利枢纽工程混凝土力学性能对比研究

Comparative study on mechanical properties of concrete for a hydraulic complex project

为探讨大坝混凝土的相关力学性能及断裂特性,基于某水利枢纽工程提供的两种不同混凝土配合比(根据含水率的不同分别命名为C_(0.48)和C_(0.43))及现场粗细骨料,开展混凝土梁三点弯曲试验,测定其坍落度、抗压强度、劈裂强度等相关力学性能参数,并分析不同配合比对断裂面、起裂荷载与失稳荷载、临界有效裂缝长度及双K断裂韧度等断裂参数的影响。结果表明:C_(0.48)混凝土的坍落度大于C_(0.43)混凝土的坍落度,C_(0.48)混凝土的抗压强度和劈裂强度均小于C_(0.43)混凝土的;C_(0.48)混凝土断裂面的粗骨料较C_(0.43)混凝土断裂面凸出不明显;C_(0.43)混凝土的起裂荷载与失稳荷载、临界有效裂缝长度及断裂韧度均比C_(0.48)混凝土的要大,具有强度高、延性和韧性好的特点。

In order to discuss the mechanical properties and fracture characteristics of dam concrete,a three-point bending test of concrete beam was carried out based on two different concrete mix ratios(named C_(0.48)and C_(0.43)respectively according to different moisture contents)provided by a hydraulic complex project and on-site coarse and fine aggregates.The relevant mechanical properties such as slump,compressive strength and splitting strength were determined,and the effects of different mixing ratios on fracture parameters such as fracture surface,cracking load and instability load,critical effective crack length and double K fracture toughness were analyzed.The test results show that the collapse of C_(0.48)concrete is greater than that of C_(0.43)concrete.The compressive strength and splitting strength of C_(0.48)concrete are lower than those of C_(0.43)concrete.The coarse aggregate of C_(0.48)concrete fracture surface is not as obvious as that of C_(0.43)concrete.The cracking load,destabilization load,critical effective crack length and fracture toughness of C_(0.43)concrete are higher than those of C_(0.48)concrete,which indicates that C_(0.43)concrete has high strength,good ductility and good toughness.