地震工程学报Issue(3)：727-733,7.DOI:10.3969/j.issn.1000-0844.2014.03.0727
黏粒含量对粉土液化后特性影响的试验研究
Influence of Clay Content on Post-liquefaction Characteristics of Silt
摘要
Abstract
Silt is one of the most common soils encountered in the field,and it is prone to liquefac-tion when earthquakes occur.In China,silt is widely located in the zones of the Qiantang River,the Yellow River,the cities of Kunming and Tangshan,and numerous other regions.The topic of silt liquefaction has been one of the hottest issues since the 1 976 Tangshan earthquake.This paper presents the post-liquefaction stress-strain characteristics of silt samples with different clay con-tents induced by strong earthquakes.Large deformations occur during the post-liquefaction stage, which may trigger a large amount of horizontal ground movement or destroy the structure built there.It is of great importance to take precautions when confronting post-liquefaction deformation induced by earthquakes,especially on horizontal ground.Silt samples with clay contents of 3%, 6%,8%,9%,12%,and 15% were used in this research.The original silt,sand,and clay samples were mixed in different mass proportions in order to obtain silt samples with different clay con-tents.The influence of the clay content on the degree of post-liquefaction deformation was studied by a series of monotonic tests.The test was based on liquefied silt samples by using a specially made triaxial apparatus.Large deformations can be recorded using the adequately large displace-ment sensors in this apparatus.These samples with different clay contents were isotropically con-solidated to the specified pressure.Then cyclic loading was performed to trigger the initial lique-faction and was maintained until the specified severity of liquefaction was reached.Finally,mono-tonic loading was conducted to simulate the post-liquefaction stage based on the liquefied silt sam-ples.Undrained shear tests were performed during the cyclic and monotonic loading stages.The post-liquefaction shear stress and shear strain were recorded automatically for these test results. From the stress-strain relationship of different clay contents,the 3% and 15% clay content sam-ples showed less strain at the same stress level,and the 8% clay content sample showed the lar-gest strain.This phenomenon can be explained as resulting from the clay content in the silt.Clay particles acted as both the lubricant and the adherent in the silt samples.As the clay content in-creased,the lubrication decreased and the glutinousness increased.There exists a critical clay con-tent level,where the post-liquefaction strain reaches a maximum at a constant stress level.This explanation is consistent with the effect of clay particles in silt on the cyclic shear stress ratio.The silt sample with 8% clay content produced the minimum shear stress ratio during the cyclic load-ing stage and thus the maximum strain during the monotonic loading stage.The effect of the clay content on post-liquefaction characteristics can be quantifiably evaluated from our test results.As is known,the strain at nearly zero effective stress was the key strain component of post-liquefac-tion deformation.The relationship between deformation and the cyclic maximum strain was linear for silt samples with different clay contents.The slopes of these lines reflect the effect of clay con-tent on post-liquefaction stress-strain.Therefore,the effect of the clay content on post-liquefaction characteristics was calculated.It was confirmed that the silt post-liquefaction stress-strain formula compared well with data collected from other tests.关键词
粉土/液化后/黏粒含量/应力-应变Key words
silt/post-liquefaction/clay content/stress-strain分类
建筑与水利引用本文复制引用
曾长女,冯伟娜..黏粒含量对粉土液化后特性影响的试验研究[J].地震工程学报,2014,(3):727-733,7.基金项目
国家自然科学基金项目(51108160) （51108160）
