飽和度對砂土動態力學行為之研究

Abstract

本文乃針對雲林麥寮砂，以中空扭剪三軸儀進行飽和度對砂土動態行為之研究，將砂土製 作成不同相對密度（30%、50%、70%），不同飽和度（50%、70%、85%、100%）的試體，施 加正弦波剪應力，探討未飽和砂土之破壞強度及超額孔隙壓力的激發情形。 試驗結果顯示：（1）飽和度相同，相對密度愈大，愈不易破壞，且隨相對密度愈大，強 度增加的幅度越大。（2）隨飽和度變小，強度愈高，強度增加的幅度趨緩。（3）將不同 相對密度、飽和度的砂土強度試驗結果,以體積減少遣能之概念歸納得到砂土液化評估之 關係式.(4)未飽和砂土亦可被激發100%的孔隙壓力,其達到加速激發期之孔隙壓力比隨飽 和度越低而越小. This research disscusses about the effect of degree of saturation on dynamic b ehavior of sand by using hollow torsional shear equipments . Specimens of diff erent relative density (30%,50%,60%,70%)and degree of saturation (50%,70%,85%, 100%) are suffered dynamic load of sine wave .From tests which mentioned above, failure strength of unsaturated sand and rousing state of excess pore pressure can be understood. The results shows that:(1)if degree of saturation are equal ,the relative dens ity is ,the stronger dynamic strength is.(2)As degree of saturation decrease , dynamic strength becomes large ;but increasing range of dynamic strength becomes small.(3)From experimental results of different relative density and degree of saturation,we can get the expression of liquefaction potential of sand by means of the notion of volume decrease potential.(4)Unsaturated sand can also be inspired 100% pore pressure ,the pore pressure ratio which reaches the rapidly increasing time becomes small as degree of saturation decrease.