十八胺改性下膨胀土斥水与变形特性试验研究

Hydrophobility and Expansion Deformation Characteristic of Modified Expansive Soil by Octadecylamine

采用十八烷基伯胺(十八胺)作为斥水剂掺入重塑膨胀土中,配置了不同含水率和十八胺含量的改性膨胀土。采用滴水穿透时间法测定了改性膨胀土的斥水等级,开展了相应的无荷与有荷膨胀率试验,获得了十八胺含量、含水率对膨胀土膨胀变形的影响规律。结果表明:十八胺含质量分数为0.8%的改性膨胀土具有极度斥水等级,且斥水性保持稳定。随着含水率和十八胺含量的增加,改性膨胀土的无荷膨胀率和有荷膨胀率均逐渐降低,并趋于稳定。当十八胺含量从0%增加到0.8%时,无荷膨胀稳定历时从97 h缩短至47 h,且膨胀率从12.9%降至9.4%。当十八胺质量分数为0.8%时,含水率为20%的改性膨胀土,其有荷膨胀率从50 kPa时的2.14%降至400 kPa时的0.01%。当荷载较小时,十八胺含量和初始含水率对有荷膨胀率有较大影响;荷载较大时,荷载成为影响有荷膨胀率的主要因素。

Primary octadecylamine was used to repellent the remolded expansive soil,and the moisture content was 5%,10%,15%,20%and modified expansive soil with octadecylamine content of 0%,0.2%,0.5%and 0.8%respectively.The water repellency grades of the modified expansive soils were measured by the drop water penetration time method,and the corresponding unloaded and charged swelling rate tests were carried out.The effects of octadecylamine content and moisture content on the swelling deformation of the expansive soil were obtained.The results show that the modified expansive soil with an octadecylamine mass fraction of 0.8%has a drip penetration time exceeding 3600 s,which owned an extremely water-repellent grade.When the octadecylamine content increased from 0%to 0.8%,the stability duration of no-load expansion was shortened from 97 h to 47 h,and the expansion rate decreased from 12.9%to 9.4%.When the octadecylamine content is 0.8%and the moisture content of modified expansive soil is 20%,its charge swelling rate decreases from 2.14%at 50 kPa to 0.01%at 400 kPa.When the load is small,the octadecylamine content and the initial moisture content have a greater influence on the swelling rate of the load.When the load is large,the load is an important factor affecting the expansibility of expansive soil.