重塑压实黏土Ⅰ型断裂试验研究

摘要

In order to study the fracture toughness KICof a remoulded clay,a new apparatus was developed on the basis of the strain-controlling direct shear apparatus,which eliminates the influence of self-gravity of the samples in the traditional three point bending test.A series of experiments are conducted on he remolded clay samples.The experimental results show that the newly developed apparatus is reliable for the measurement of the fracture toughness of soil.For the soil samples with identical moisture content and dlry density,the fracture toughness for the samples with U-shaped initial cracks is the greatest and that with triangle initial cracks is the smallest.The moisture content and dry density of soil samples have great effects on their fracture toughness.For the samples with identical dry density,the fracture toughness first increases and then decreases with the increasing moisture content,meaning that there is an optimal moisture content at which the fracture toughness is the greatest.For the samples with identical moisture content,the fracture toughness increases with the increasing dry density.The various loading rates used in this paper have little effect on the fracture toughness.%为探究重塑黏土Ⅰ型断裂韧度,本文在前人研究基础上,通过对应变控制式直剪仪进行改造,消除了传统三点弯曲试验对土体断裂韧度测试所带来的影响,研制了土体Ⅰ型断裂韧度测试仪,并对重塑黏土进行了一系列试验.试验结果表明:新研制出的土体Ⅰ型断裂韧度测试仪具有较好的可靠性;对具有相同物理状态的试样,U形裂纹试样的断裂韧度最大,三角形裂纹试样的断裂韧度最小;试样的含水率和干密度其断裂韧度KIG具有显著影响,随含水率增加,断裂韧度呈现先增后减的变化规律,而随干密度增加,断裂韧度几乎线性增加;在试验采用的加载速率范围内,加载速率对断裂韧度的影响较小.