Experimental study on characteristics of bending cracks of compacted soil beams

The waterproofing properties of compacted clay barrier at landfill site will be significantly weakened by cracks. To reveal the characteristics of bending cracks of compacted soil beams with different water contents, a bending test apparatus is developed. Then the process of crack propagation is investigated. The strain localization near the crack tip is analyzed using PIV technology, and cracking strain of compacted soil beams with different water contents is obtained. The experimental results show that many strain localization regions are observed in the tensile zone of the beam, and the strain localization region near the mid-span becomes the macroscopic crack. The crack width increases linearly with the growth of mid-span displacement, which is independent of the water content. However, the water content has great influence on the cracking characteristics and strain of the beam. As the water content increases from 32.6% to 37.0%, the crack deflection of the beam increases markedly, the area of strain localization near the crack tip expands, and cracking strain increases from 2.4% to 4.1%. Additionally, as the water content increases, the pattern of load versus the mid-span displacement changes from “snap back” to “skip through”, and the peak load decreases noticeably. It is indicated that the crack pattern of compacted soil beams changes from brittle fracture to ductile one.