Ⅰ型裂缝经弱界面钝化扩展实验研究1)

EXPERIMENT STUDY OF I TYPE CRACK BLUNT EXTENSION INDUCED BY WEAK PLANE1)

  • 摘要: 天然裂缝或层理等弱界面的剪切破坏是体积压裂裂缝网络形成的关键因素。利用数字散斑相关技术,通过三点弯曲构建了I型裂缝经过弱界面时的扩展特性实验,获得了试件表面位移场和应变场的变化规律。实验结果表明:I型裂缝扩展至弱界面层后,裂缝发生短暂停滞扩展,裂缝尖端张开位移迅速增加,I型裂缝尖端钝化,弱界面剪切应变迅速增加,裂缝由I型裂缝转变为I-II复合型裂缝并转向扩展。

     

    Abstract: Shear failure of weak interface as natural cracks or bedding is the key factor for the formation of crack network. Based on the principle of a three-point bending test, this paper sets up the test bed of mode I crack extension weak plane. The digital image correlation method is used to obtain the specimen surface displacement and strain field changes when the crack extends through the weak plane. The experiment results show that: when the crack extended at the weak interface, the extension stopped transitory, the COD (crack opening displacement) increased rapidly, the crack blunted, the shear strain increased rapidly, the mode I crack transforms to a mixed mode I-II crack and the crack extended deflective.

     

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