三轴试样钻孔灌砂固结排水效果试验研究

Consolidation and drainage effect of drilling and sand replacement samples in consolidated drained triaxial tests

对渗透性较差的重黏土样进行固结排水试验时,其饱和、固结、剪切过程时间较长。为提高固结排水试验效率,改进了三轴排水工艺,提出在试样中钻孔灌砂形成竖向排水通道,并进行了针对黏土样的固结排水试验的验证。试验结果表明,1%～3%置换率的砂井对固结排水试验应力-应变无影响,并有利于加速三轴试样的饱和、固结排水、孔压消散、剪切排水过程,可使试验效率提高5倍以上;试样周边、顶面、底面粘贴滤纸条,再结合试样内部钻孔灌砂,是改善三轴试验排水路径的一种科学合理的、高效的方法,能够获得准确、可靠的E-B模型参数。

When the soil sample which has the feature of poorer permeability is used to do consolidated drained triaxial tests, its processes of saturation, consolidation and shearing will take a long time. A new drilling and sand replacement method of consolidated drained triaxial tests which is done by drilling and replacing sand in soil samples is put forward to improve the test efficiency; and the verification of this test has been done. As the experiment result of the scheme indicated, the sand drain, the replacement ratio of which are between 1% and 3 %, has small effect on the stress and strain of consolidated drained triaxial tests, at the same time is beneficial to accelerate the soil sample＇s process of saturation, consolidation and drainage, pore pressure dissipation, shearing and drainage, and so on. The test efficiency is 5 times higher than that of before. The filter papers are pasted from top to bottom of the soil sample and the boreholes inside it are filled with many sands. Combining the above two practices, this method is a scientifically rational, effective and good method which has attained accurate and reliable parameters of the E-B model.