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裂缝的存在显著降低黏土层的防渗性能。研制了土梁弯曲试验装置,研究了不同含水率压实黏土梁张拉开裂性状,分析了裂纹扩展过程,并采用PIV技术揭示了裂纹尖端的应变局部化现象,获得了不同含水率下压实黏土的开裂应变。试验结果表明:三点弯梁拉伸区可能出现多个应变局部化区域,其中靠近跨中的一个发展为宏观裂纹;裂纹宽度随中点挠度近似呈线性增长,且受含水率影响较小;含水率对土梁开裂特性和开裂应变影响很大,随着含水率由32.6%增至37.0%,土梁断裂挠度显著增加,裂纹尖端的应变局部化区域变大,开裂应变从2.4%增大至4.1%,跨中荷载挠度曲线呈现由跳回型向跳过型变化,荷载峰值明显降低,土梁由脆性断裂逐渐转变为延性断裂。
The presence of cracks significantly reduces the seepage resistance of the clay layer. The bending test device for earth beam was developed. The tensile cracking behavior of clay beam with different moisture contents was studied. The crack growth process was analyzed. PIV technique was used to reveal the strain localization at crack tip. Clay cracking strain. The experimental results show that a number of strain localized areas may appear in the three-point stretch zone, of which one near the mid-span develops macroscopic cracks. The width of the crack increases approximately linearly with the midpoint deflection and is less affected by the moisture content. Moisture content has a great influence on the cracking behavior and cracking strain of soil beam. As the moisture content increases from 32.6% to 37.0%, the deformation of soil beam increases significantly, and the strain localization area at crack tip becomes larger and the cracking strain increases from 2.4% To 4.1%. The deflection curves of the mid-span load ranged from skip-to-skip type to skip-type and the peak value of loads decreased obviously. The soil beam gradually changed from brittle fracture to ductile fracture.