不同初始缝高比楔入劈拉试件断裂试验研究

为研究初始缝高比对混凝土断裂性能的影响，设计4组共32个不同初始缝高比的试件进行楔入劈拉试验。测定试件断裂过程中的荷载、裂缝张口位移、混凝土应变等参数的特征值及全过程曲线。以双 K 断裂理论为基础，计算不同初始缝高比试件的有效裂缝长度 ac、起裂断裂韧度 KiniIC 和失稳断裂韧度 KunIC 等断裂参数。试验结果表明：有效裂缝长度 ac 随缝高比的增大而增大，裂缝亚临界扩展量Δac 随缝高比的增大而减小；起裂断裂韧度不受初始缝高比的影响，失稳断裂韧度随缝高比的减少有所增大，当 a0／D≥0．5时，为一常数。

Fracture Toughness of Specimen with Different Initial Seam-Height Ratio under Wedge Splitting Test

The effect of initial seam-height ratio on concrete’s fracture performance was researched through wedge splitting test.Four groups including 32 specimens with different initial seam-height ratio were tested.The eigenval-ues of parameters and the corresponding process curves of complete load,crack opening displacement and concrete surface strain were determined.Fracture parameters inclusive of effective crack length ac ,initial fracture toughness KiniIC and unstable fracture toughness KunIC were calculated based on double-K fracture theory.Results indicate that along with the increase of seam-height ratio,the effective crack length ac increassd and the subcritical crack propa-gation length Δac reduces;KiniIC is not affected by the initial seam-height ratio,and KunIC increases with the reduction of seam-height ratio,but when a0 /D≥0.5,it can be considered as a constant.