南京砂强度特征与静态液化现象分析  

Analysis of strength characteristics of Nanjing sand and mechanism of static liquefaction

作　　者：朱建群[1] 孔令伟[1] 钟方杰[1] 

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室

出　　处：《岩土力学》2008年第6期1461-1465,1470,共6页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.40372128)

摘　　要：在松散、中密和密实状态下,以南京粉细砂三轴固结不排水试验结果为基础,进行了强度、变形与静态液化特征的分析。松散南京砂强度特性表现出典型的应变软化,当轴向变形小于1%时强度达到最大值,而后急剧降低;在50,100 kPa围压时发生了静态液化。但随着固结压力的增大,静态液化消失。与南京砂具有相同土骨架的松散纯净砂却在低围压下未出现静态液化,其形成机制是:粉粒的存在未使土体孔隙比发生较大变化,却引起更大的体缩性;中密和密实南京粉细砂表现出加工硬化的强度特征,临界应力状态线倾角高达55°,具有较高的抗静态液化能力。Undrained triaxial compression tests were performed on these reconstituted samples of Nanjing sands at three different relative densities and the results of an experimental study are presented.All tests were performed under monotonic loading.It is evaluated and analyzed to the stress-strain relationship and the probability of the static liquefaction.At low densities,samples exhibited typical strain-soften characteristics,in which peak strength arrived when the axial strain was below 1%;then deviator stress decreased rapidly.Moreover undrained triaxial tests showed static liquefaction（zone stress difference） at the confining pressure of 50kPa and 100kPa.As confining pressure were increased,static liquefaction disappeared and the effective stress paths indicated increasing resistance to liquefaction.Compared with Nanjing fine sand,clean sand,which has no fine granular,didn’t exhibit the static liquefaction at low confining pressure.So it is hypothesized that the presence of fines（particles smaller than 0.075mm） in the soil structure doesn＇t bring out the notable changes of and,but provides the highly compressibility.At media dense and dense Nanjing sand show the strain-harden characteristics,and the slope of critical stress path arrives 55°with high resistances of static liquefaction.

关 键 词：南京砂 强度 固结不排水试验 静态液化 

分 类 号：TU411[建筑科学—岩土工程]