Laboratory Test Study On The Influence Of Percent Fines On Silt Liquefaction And Post-liquefaction

Liquefaction has been studied for long time. The factors that affect the probability of sand liquefaction and the experiential expressions of sand liquefaction have been well studied. And the studies for problem of the silt liquefaction and sand post-liquefaction are ongoing. However, little research is done for silt post-liquefaction in this field. Silt is a special soil which is made up of three particles as sand particle, silt particle and clay particle. Silt fraction and clay fraction in silt are generally called fines. It is still deserved to study the liquefaction strength and dynamic pore water pressure and post-liquefaction character of silt when the clay particle content and silt particle content change.Many tests on the influence of percent fines on silt liquefaction and post-liquefaction are conducted firstly in this paper. The influence of fines on the dynamic strength is studied based on the liquefaction tests. And a model of dynamic pore water pressure is also concluded considering the influence of fines. The silt post-liquefaction stress-strain relationship under different conditions is analyzed based on the post-liquefaction tests. At last the prediction of the lateral deformation induced by post-liquefaction in silt ground is done. The main contents of the dissertation are as followings:1. The liquefaction tests are performed by a multi-function tri-axial apparatus to study the influence of fines on liquefaction strength. In these tests, the clay content of silt increases as 3%, 6%, 9%, 12%, 15% while the sand content remains unchanged and the silt content increases as 50%, 60%, 70%, 80% while clay content remains unchanged. It is proved that not only dry density but also the particle content change of clay content and silt content affect liquefaction strength. The effects of dry density on silt liquefaction strength are well studied. In the tests, we focus on the influence of fines on liquefaction strength. When the clay content of silt changes its effect on liquefaction strength is not a monotone line. When the clay content is 8% it reaches the lowest value which is consistent to the conclusions from many other researchers. When the silt content of silt changes its effect on liquefaction strength is monotone. The liquefaction strength increases with the increase of silt content. It is preliminarily explained for this phenomenon by the particle effect on liquefaction.2. The development of pore water pressure is studied by new tests which is remedied the literature author conclusion. The tests memorize the whole process of the dynamic loading from the beginning to initial liquefaction until it reached the severity degree of liquefaction. While the literature author conclusion was based on the tests which stopped as soon as the initial liquefaction occurred. So it can't reflect the whole process. An extensive model is extracted from...