骨架颗粒组成对散粒土管涌规律影响的试验研究

Experimental study on the effect of skeleton particle composition on piping law of cohesionless soil

利用改进的渗透装置试验研究了细颗粒(0.075~1 mm)含量相同时骨架颗粒组成含量不同对散粒土的管涌发生临界条件以及颗粒侵蚀流失规律的影响,结果表明:不同颗粒级配的试样在管涌发生前,水力梯度与渗流速度呈线性关系,基本符合达西定律;骨架颗粒1~2、2~3、3~5 mm 3个粒径段对管涌发展起到了阻碍作用,其中1~2 mm粒径段颗粒对管涌孔隙的堵塞作用强于另外两个粒径段颗粒;对于不同级配的骨架颗粒,其不均匀系数越大,试样的下限临界水力梯度值就越大,细颗粒越不易起动,发生管涌的时间越晚,而不同级配的骨架颗粒对试样的上限临界水力梯度影响较小。

An improved permeation device was developed for the experimental investigation of the influence of different skeleton particle compositions with the consistent content of fine particle ranging(0.075 to 1 mm)on critical conditions of piping,erosion pattern and loss pattern of particles in the granular soil.The results show that for samples with different particle gradations,the hydraulic gradient and the seepage velocity exhibit a linear relationship before piping occurs,which essentially complies with Darcy’s Law.Skeleton particles in the size ranges of 1-2 mm,2-3 mm,and 3-5 mm impede the development of piping,with particles in the 1-2mm range demonstrating a stronger blocking effect on piping voids than particles in other two size ranges.For skeleton particles of different gradations,the larger the heterogeneity coefficient,the larger the lower limit of the critical hydraulic gradient for the sample,making it more difficult for fine particles to be mobilized,and thus delaying the onset of piping.Conversely,the influence of the skeleton particle gradation on the upper limit of the critical hydraulic gradient of the sample is relatively minor.