地震历史对各深度土体抗液化性影响的振动台试验研究  

Shaking table test study on the influence of seismic history on liquefaction resistance of soils at different depths

作　　者：王晓磊[1] 刘理腾 刘润[2] 刘历波[1] 董林 任海 WANG Xiao-lei;LIU Li-teng;LIU Run;LIU Li-bo;DONG Lin;REN Hai(College of Civil Engineering,Hebei University of Engineering,Handan,Hebei 056038,China;Institute of Geotechnical Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]河北工程大学土木工程学院,河北邯郸056038 [2]天津大学岩土工程研究所,天津300072

出　　处：《岩土力学》2023年第9期2657-2666,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金联合重点基金(No.U21A20164);国家杰出青年科学基金(No.51825904);国家自然科学基金项目(No.51708525)。

摘　　要：地震引起的液化会对岩土结构造成重大破坏,而震后伴随的余震可能导致砂土再次发生液化。为研究自由场地下地震历史对各深度饱和砂土的抗液化能力的影响,设计并开展了一系列振动台试验。试验中对砂土输入了4次不同加速度的震动事件,细分为7次小的事件。通过计算对比每次振动事件的超静孔压比、加速度响应以及土体沉降,以研究不同地震历史下各深度土体抗液化能力的变化规律。试验结果表明:输入的地震波加速度大小与加速度响应系数呈正相关关系;饱和砂土遭受轻微和中等地震时液化更容易发生在浅层而非表层;表层土体中,强烈地震后的中等余震使得土体对地震烈度的敏感性降低,孔隙水压力在峰值加速度后消散迅速,液化时间缩短;有强震历史的土体会降低浅层土体的抗液化性能,深层土体抗液化性反而会在经历强地震后增强,影响深度范围取决于地震的烈度;通过数据拟合得到了不同等级的循环地震在各深度土体的抗液化提升比的量化公式。试验结果可以反映在地震实际中各等级的地震历史对各深度土体的不同影响。Earthquake-induced liquefaction can cause significant damage to geotechnical structures,and the aftershocks accompanying the earthquakes may cause the sandy soils to liquefy again.To investigate the effect of free-field subsurface seismic history on the liquefaction resistance of saturated sandy soils at various depths,a series of shaking table tests was designed and conducted.Four shaking events with different accelerations,subdivided into seven smaller events,were input to the sandy soil in the tests.The excess pore pressure ratio,acceleration response,and soil settlement were calculated and compared for each vibration event to investigate the variation laws of soil liquefaction resistance at various depths under different seismic histories.The test results show that the magnitude of the input seismic wave acceleration is positively correlated with the acceleration response coefficient.Liquefaction of saturated sandy soils subjected to minor and moderate earthquakes is more likely to occur at shallow rather than superficial layers.In superficial soils,moderate aftershocks after strong earthquakes make the soils less sensitive to seismic intensity,pore water pressure dissipates rapidly after peak acceleration,and liquefaction time is shortened.Soils with strong seismic histories reduce the liquefaction resistance of shallow soils,while the liquefaction resistance of deep soils is enhanced after strong earthquakes,and the affected depth range depends on the earthquake intensity.Quantitative formula of the liquefaction-resistant lifting ratio of soil at different depths under different levels of cyclic earthquakes is obtained through data fitting.The test results can reflect the different effects of different seismic histories on the soils at various depths in the actual earthquake.

关 键 词：地震历史 砂土液化 抗液化性能 超静孔隙水压力 振动台试验 

分 类 号：TU411.93[建筑科学—岩土工程]