砾质土钻孔灌砂工艺三轴试验效果研究

Triaxial Tests Effect Study on Drilling and Pumped Sands of Gravelly Soil

对砾质土心墙料渗透性较差的试样，若按传统方法进行三轴试验，要保证试样饱和、固结、剪切过程中排水充分，试验周期将很长，无论是从大型三轴试验仪设备性能还是试验时间上都是难以接受的。为提高三轴试验效率，研制改进了三轴排水工艺，并进行了三轴CD试验的验证。试验成果表明：1％-3％置换率的“砂井”，对加速三轴试样的饱和、固结排水和孔压消散等过程起到了显著的效果，试验效率提高了2～3倍，但对应力应变基本无影响；从无孔样到有孔样，c值具有离散性，妒值依次增加，但变化幅度不大；试样周边、顶底粘贴滤纸条，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、有效简便的好方法，能够获得准确、可靠的抗剪强度指标和E-B模型参数。

If the gravelly soil used for core impervious material, which has the poorer permeability, is needed to do consolidated drained triaxial tests by traditional methods for reaching the target of enough saturation and consolidation, the test processes of saturation, consolidation and shearing will take a long time. Generally speaking, traditional method is unacceptable. From the device performance of large-scale triaxial test instrument or test time. To improve the test efficiency a new drainage method of consolidated drained triaxial tests was put forward in this paper, and the verification on the test has been done. As the experiment result of the scheme indicated, the sand drain, the replacement ratio of which is between 1% and 3 % , has little effect on the stress and strain , and soil shear strength index, but it is significantly beneficial to accelerate the soil sample＇ s processes of saturation, consolidation, drainage, pore pressure dissipation and so on . The test＇ s efficiency is 2 or 3 times higher than before. From an imperforate sample to a drilled sample, c is scattering, and the value of φ increases in range of relatively small changes. The filter papers are pasted from top to bottom of the soil sample and the boreholes inside it are filled with sands, thus this method is considered to be a scientifically rational , effective and good method. It can attain the accurate and reliable shear strength index and parameters of the E-B model.