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一、前言 在混凝土Ⅰ,Ⅱ复合型裂纹断裂测试研究中,为了要得到一条比较稳定的断裂临界曲线,对于K_Ⅰ,K_Ⅱ不同组合的各试样应尽量采用统一而简单的形式。我们曾经采用过 直偏裂纹和斜偏裂纹的三点弯曲试样,但均不够理想。通过探索比较,我们认为反对称加载的单边裂纹四点剪切试样是比较合适的,其试样尺寸和加载位置可固定不变,只要改变裂纹位置就可得到不同的K_Ⅰ,K_Ⅱ组合,并可较方便地测定纯K_Ⅰ和纯K_Ⅱ两个极端情况。此外,这种试样在浇制及试验装置上也较方便,并保持了试验条件的一致
I. INTRODUCTION In the composite crack test tests for concrete I and II, in order to obtain a relatively stable fracture critical curve, each specimen of different combinations of K_I and K_II should adopt a unified and simple form as far as possible. We have used three-point bending specimens with straight cracks and oblique cracks, but none of them are ideal. By exploring and comparing, we believe that the unilaterally-cracked four-point shear specimen with anti-symmetric loading is more appropriate, and the specimen size and loading position can be fixed and unchanged, and different K_I, K_II combinations can be obtained by simply changing the position of the crack. The two extreme cases of pure K_I and pure K_II can be easily measured. In addition, this kind of sample is also convenient for casting and testing equipment, and it maintains the same test conditions.