为研究混凝土断裂性能,对预制切口混凝土梁进行三点弯曲试验,利用电子散斑干涉(Electronic Speckle Pattern Interferometry,ESPI)技术测量梁表面的场位移。为进行对比分析,采用线性位移传感器(Linear Variable Differential Transformers,LVDTs)和夹式位移计分别测量试件梁的跨中挠度(δ)和裂缝口张开位移(Crack Mouth Opening Displacement,CMOD)。试验结果表明:ESPI测量的结果与LVDTs、夹式位移计测得结果比较吻合,证实了ESPI测量梁表面场位移的精确性和可行性。在峰值荷载,CMOD约为27μm,挠度δ约为58μm,裂缝尖端位移CTOD约19.2μm。ESPI结果表明,试件梁主裂缝起始于预制切口尖端,沿着接近切口平面的路径向试件梁顶部的加载点扩展,裂缝轨迹呈蜿蜒状。断裂过程区集中在梁跨中附近,宽度约为10mm~15mm,在裂缝发展初期呈核状,在裂缝发展后期呈不规则的狭长带状。 To study the fracture behavior of concrete, a three-point bending test was conducted on the prefabricated concrete beams and the field displacement was measured by using the Electronic Speckle Pattern Interferometry (ESPI) technique. For comparative analysis, the mid-span deflection (δ) and the Crack Mouth Opening Displacement (CMOD) of the specimen beam were measured by using Linear Variable Differential Transformers (LVDTs) and clip-on displacement meters respectively. The experimental results show that the ESPI measurement results are in good agreement with the LVDTs and the clamp-type displacement meters, confirming the accuracy and feasibility of ESPI in measuring the displacement of the beam surface. At peak load, the CMOD is about 27μm, the deflection δ is about 58μm, and the crack tip displacement CTOD is about 19.2μm. The results of ESPI show that the main crack in the specimen starts from the tip of prefabricated incision and extends along the path near the incision plane to the loading point at the top of the specimen beam. The crack trajectories are meandering. The fracture process area is concentrated near the midspan of the beam, with a width of about 10mm-15mm, showing a nucleus at the initial stage of fracture development and an irregular narrow strip shape at the later stage of fracture development.