白鹤滩大坝低热水泥混凝土断裂性能试验研究

Experimental study on fracture properties of low heat cement concrete of Baihetan dam

为正确评价白鹤滩大坝低热水泥湿筛混凝土断裂性能,在施工现场浇筑成型5组有效高度为200~600 mm,初始缝高比为0.4的楔入劈拉混凝土试件,开展不同尺寸试件的断裂性能试验。根据试验结果,采用双K断裂准则对低热水泥湿筛混凝土断裂性能的尺寸效应展开分析。结果表明:不同尺寸试件起裂荷载与峰值荷载的比值为0.66~0.87;当试件有效高度达到500 mm时,即可得到稳定的起裂断裂韧度、失稳断裂韧度和断裂能,分别为1.26 MPa·m^(1/2),1.98 MPa·m^(1/2)和320.79 N/m。研究成果可为白鹤滩大坝开裂风险分析提供必要的材料参数。

To correctly evaluate the fracture properties of low heat cement wet-sieved concrete of Baihetan dam,five groups of wedge-splitting specimens with effective heights from 200 mm to 600 mm and initial crack to height ratio 0.4 were cast on the construction site and tests on the fracture properties of specimens with different sizes were performed.According to the test results,an analysis is made on the size effect of fracture properties of low heat cement wet-sieved concrete based on the double-K fracture criterion.The results show that the ratio of initial cracking load to peak load for different specimen sizes ranges from 0.66 to 0.87.When the effective height of specimens is 500 mm,the stable initiation fracture toughness,unstable fracture toughness and fracture energy can be obtained as 1.26 MPa·m^(1/2),1.98 MPa·m^(1/2) and 320.79 N/m,respectively.The research results can provide necessary material parameters for the cracking risk analysis of Baihetan dam.