弱膨胀土的膨胀特性试验研究

EXPERIMENTAL STUDY OF SWELLING CHARACTERISTICS OF WEAK EXPANSIVE SOIL

目前测量土体膨胀力的主要方法有膨胀反压法、加压膨胀法、平衡加压法和恒体积法。基于测量膨胀力的恒体积法,利用TST-55型渗透仪、高精度压力传感器和数采系统改进了测量土体膨胀力的装置,并研究了膨胀土的膨胀特性。试验结果表明,土样初始含水率和干密度对土体的极限膨胀力都有显著的影响,并建立了极限膨胀力与两者之间的关系式;较低初始含水率时,不同干密度的土样在膨胀力达到峰值之后,都有不同幅度的降低,随着干密度的增大而降低的越多,并且发现极限膨胀力降低值与干密度之间在双对数坐标轴上存在线性关系;而在较高初始含水率时,不同干密度的土样在膨胀力达到峰值之后,会保持平稳趋势。极限膨胀力的对数与初始含水率之间具有很好的线性关系,土样吸水量的对数与初始含水率以及干密度均有着很好的线性关系。

At present,the main soil swelling force measuring methods include swelling-consolidation method,pressure swelling method,balance pressure method,constant volume method. Based on the constant volume method of measuring soil swelling force,the TST-55-type permeameter,high-precision pressure sensors and data acquisition system are used to improves measuring method of soil swelling force,and to study the expansion characteristics of expansive soil. Test results show that the initial water content and dry density of soil sample have a significant influence to limit swelling force. The paper establishes the equation for their relation with limit swelling forces. At lower initial water content,when soil sample＇s limit swelling force of different dry density reaches a peak,it has a different rate of decrease. The value along with increasing of the dry density can be decreased. A linear relationshipexists in the double logarithmic coordinate axis about the reduction value of limit swelling force and the dry density.At higher initial water content,when soil sample＇s limit swelling force of different dry density reaches a peak,it will remain stable trend. There is a good linear relationship between the logarithm of limit swelling force and initial water content. There is also a good linear relationship between the logarithm of water absorption of soil sample and initial water content or dry density.