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为了评定混凝土大坝接缝灌浆质量及其稳定性,需要研究接缝灌浆发生剪切断裂的断裂特性并测定其相应的剪切断裂韧度。本文采用两端预留缝半边受力试件,进行了混凝土大坝接缝灌浆材料的剪切断裂试验,利用混凝土的导电特性对有限宽两端预留缝半边受力试件的断裂性能进行研究。结果表明,两端预留缝剪切断裂试件可以用来进行接缝灌浆材料的断裂试验及测定接缝灌浆材料的断裂韧度;剪切起裂点可能出现在灌浆缝与受压端的交界处,也有可能出现在灌浆缝与自由端的交界处;灌浆缝剪切断裂是一个逐渐扩展的过程,裂缝沿着灌浆缝直线或者曲线扩展;接缝灌浆材料的断裂韧度对试件高度和宽度存在尺寸效应,而对初始缝高比的尺寸效应不明显;接缝灌浆材料的导电性能随荷载和位移有显著的变化,可以用来确定该型试件剪切断裂的临界荷载。
In order to evaluate the grouting quality and stability of concrete dam, it is necessary to study the fracture characteristics of the joint grouting and determine the corresponding shear fracture toughness. In this paper, a half-side prestressed semi-reinforced specimen with both ends was used to carry out the shear fracture test of the concrete dam grouting material. The fracture behavior of concrete specimens with semi- the study. The results show that the specimen with both ends can be used for the fracture test of the grouting material and the fracture toughness of the grouting material. The shear initiation and fracture point may appear at the interface of the grouting seam and the compression end At the junction of grout and free end. The shear fracture of grout joint is a process of gradual expansion. The fracture expands straightly or curvilinearly along grouting seam. The fracture toughness of joint grouting material affects the height and width of specimen The size effect is not obvious to the initial seam height ratio. The conductivity of the joint grouting material changes obviously with the load and displacement, which can be used to determine the critical load of shear fracture of this type of specimen.