纤维增强混凝土断裂过程区试验研究

Experimental Research on Fracture Process Zone in Fibre-reinforced Concrete

目的 研究纤维增强混凝土的韧性 .方法 利用激光散斑法对混凝土及纤维增强混凝土切口梁的断裂过程区进行了研究 .结果 对失稳断裂前微裂纹发展的全过程进行了跟踪测量 ,并得到了载荷与裂纹尖端张开位移 P-d CTO曲线 .结论 断裂过程区呈不规则狭长带状形 ,且混凝土中加入纤维后微裂纹区的扩展受到限制 ,使主裂纹的亚临界扩展长度、临界裂纹尖端张开位移增加 。

Aim\ To study the toughness of the fibre reinforced concrete. Methods\ The shapes of fracture process zones in notched concrete beam and notched fibre reinforced concrete beam are researched by means of laser speckle photography. Results\ The whole process of microcracks appearance before the occurrence of unstable fracture, and the load vs. and crack tip opening displacement curves are ditermined. Conclusion\ The shapes of fracture process zones are long, narrow and irregular bands. The length of subcritical growth for main crack, the critical crack tip open displacement and the toughness of the material are increased by adding fibre, because the growth of microcracks zone is restricted by fibre.