粘粒含量对南京粉细砂液化影响的试验研究

Experimental study on influence of clay particle content on liquefaction of Nanjing fine sand

南京粉细砂是一种以片状颗粒成分为主的粉细砂,与通常的圆形颗粒石英砂有一定区别,片状颗粒成分使得南京粉细砂具有各向异性的性质。通过对不同粘粒含量的南京粉细砂进行液化试验,分析其试验结果发现:对于粘粒含量ρ_c=5％、10％和15％三种情况,在均压固结情况下,当南京粉细砂达到初始液化时,采用变形标准和孔压标准是一致的;而偏压固结时,只能采用变形标准作为南京粉细砂达到初始液化的标准,此时振动孔压仅达到围压的50％～70％。粘粒含量对南京粉细砂的抗液化强度影响很大,随粘粒含量增加,在不同固结比时,其抗液化强度并不是单调变化,而是在粘粒含量ρ_c=10％左右处于一个低谷,其抗液化强度最低。

Nanjing fine sand mainly consists of schistous grain and is different from the common sand with round quartz grains. Nanjing fine sand is anisotropic because of the schistous grain. Through analyzing liquefaction test results of Nanjing fine sand, the following conclusions are drawn; for three cases of clay particle content ρc=5%、10% and 15% , during initial liquefaction taking place ,both liquefaction standard of strain and pore water pressure are identical under isotropic consolidation. However, under anisotropic consolidation, liquefaction standard of strain is only standard when initial liquefaction of Nanjing fine sand takes place, and vibratory pore water pressure is only 50% - 70% of confining pressure. The clay particle content has great influence on liquefaction resistance of Nanjing fine sand. With clay particle content increasing, the liquefaction resistance does not monotonously change under different consolidation ratio, while there is a 'valley' area of liquefaction resistance value on the edge of clay particle content ρc = 10% and its liquefaction resistance is the weakest.