初始剪应力作用下饱和粉土液化流动特性试验研究  

Liquefaction flow characteristics of saturated silt under initial shear stress

作　　者：周正龙 华凌霄[1] 徐令宇 赵凯[2] 吴琪[2] 陈国兴[2] ZHOU Zheng-long;HUA Ling-xiao;XU Ling-yu;ZHAO Kai;WU Qi;CHEN Guo-xing(College of Civil Engineering,Nanjing Tech University,Nanjing,Jiangsu 211816,China;Institute of Geotechnical Engineering,Nanjing Tech University,Nanjing,Jiangsu 211816,China)

机构地区：[1]南京工业大学土木工程学院,江苏南京211816 [2]南京工业大学岩土工程研究所,江苏南京211816

出　　处：《岩土力学》2024年第11期3295-3303,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.52208349,No.52378345,No.52378347)。

摘　　要：饱和粉土在地震作用下会发生液化变形,从而导致建立在其上的建(构)筑物发生破坏。工程场地区域内粉土单元通常存在初始剪应力作用,为探究初始剪应力对饱和粉土液化特性的影响,将液化后粉土视为流体进行了一系列循环扭剪试验研究。试验结果表明,初始剪应力对饱和粉土剪应力-剪应变率曲线影响显著,随着初始剪应力τ_(s)的增大,剪应力-剪应变率曲线由“椭圆形”向“哑铃形”过渡逐渐转变为由“镰刀形”向“椭圆形”至“锤形”过渡;表观黏度η与振次N的衰减曲线随着τ_(s)的增大先降低再抬升,平均流动系数κ与振次N的增长曲线发展速度随着τ_(s)的增大先加快后减慢,固液相变孔压比r_(uth)随着τ_(s)的增大先减小后增大,当τ_(s)=5 k Pa时饱和粉土的r_(uth)最小。Abstract:Saturated silt is prone to liquefaction and deformation under earthquake action,which can lead to severe damage to structures built on it.In natural conditions,saturated silt often experiences initial static shear stress τ_(s)st.To explore the impact of initial shear stress on the liquefaction characteristics of saturated silt,a series of cyclic torsional shear tests were conducted on liquefied silt,treating it as a fluid.The experimental results showed that the initial shear stress τ_(s)had a significant impact on the relationship curve of the shear stress-strain rate of saturated silt.When the initial shear stress τ_(s)equals zero,the pattern of the relationship curve transitions from the shape of an ellipse to the shape of a dumbbell as the number of loading cycles N increases.The pattern of the relationship curve successively appears as the shape of a sickle,ellipse,and hammer with increasing initial shear stress τ_(s).Meanwhile,the initial shear stress τ_(s)has a significant influence on the development of the apparent viscosityhand the average flow coefficientkof the saturated silt.As the initial shear stress increased,theh-N curve decreased first and then increased,while the development speed of thek-N curve showed a trend from fast to slow.Additionally,the excess pore water pressure ratio uth r at the solid-liquid phase transformation state first decreased and then increased as the initial shear stress increased.When the initial shear stress reached 5 kPa,the excess pore water pressure ratio of the saturated silt was the lowest.

关 键 词：饱和粉土 初始剪应力 液化流动 循环扭剪试验 

分 类 号：TU411[建筑科学—岩土工程]