蒙脱石含量对黏土表面干缩裂隙影响试验研究

摘要

As a major clay mineral in swelling soil,montmorillonite has important influence on swelling-shrinkage properties and developing fissures of swelling soil.Desiccation tests were conducted under 40℃on initially saturat-ed montmorillonite-silica sand mixture slurry to investigate the effects of montmorillonite content on shrinkage and cracking characteristics.Water loss and surface crack evolution were monitored during the whole drying period while the critical moisture content and surface crack ratio δS were obtained with computer software.The results showed that during drying period,the process of water loss showed three obvious phases:the evaporation phase at constant speed,the decline phase and the residual phase.And cracks on the surface of samples mostly developed in the first phase.The final surface crack ratio δSF and the initial moisture content wI at which the cracks start were significantly influenced by the content of montmorillonite showing trend of increasing with the growth of the content of montmorillonite.But the final moisture content wF at which the cracks end were different,yet,the differenceΔw between wI and wF is positively related to the content of montmorillonite.%蒙脱石作为膨胀土中主要的黏土矿物成分，对膨胀土胀缩性质及裂隙性具有重要的影响。为研究蒙脱石含量对裂隙发育的影响同时规避其他成分的影响，对13组不同蒙脱土含量的蒙脱土－石英砂饱和泥浆样进行了干燥试验，试验控制温度为40℃。在干燥过程中，对含水率和表面裂隙进行实时监控，并利用计算机软件对裂隙进行定量化分析，获取裂隙演化过程中的临界含水率及表面裂隙率δS。试验结果表明：干燥过程中，水分的散失表现出明显的3个阶段———常速率阶段、减速阶段以及残余阶段，且裂隙的发育主要在常速率阶段进行。试样的最终表面裂隙率δSF和起裂时的含水率wI受蒙脱土含量的影响明显，均表现为随着蒙脱土含量的增加而增加，终裂时的含水率wF并没有相同的趋势，但wI与wF之差Δw与蒙脱土含量正相关。