液化地基自由场振动台试验的土性参数识别

Parameter Identification of Liquefiable Soil in Free Field Tested on Shaking Table

基于已进行的液化地基自由场振动台试验,利用参数识别技术对试验记录的土体加速度和孔隙水压力进行分析,研究了场地液化机理及土的动力特性.由自由场振动台试验的土体加速度记录求出土体的动剪切应力—应变曲线,并研究了土体的动剪切模量及阻尼特性随动剪切应变的变化关系.结果表明:利用参数识别技术识别的土的刚度与土动力性质试验获得的数据基本一致,而阻尼要高于土动力性质试验的结果;孔隙水压力增长对土的剪切波速有影响,会引起土的刚度降低.

The characteristics of liquefiable soil during earthquake excitation of free field were identified based on multiple acceleration records in shaking table tests.The time histories of cyclic shear stress and shear strain in the soils were evaluated from the accelerations recorded in the soil.These histories were used to estimate variation of soil dynamic shear moduli and material damping characteristics with shear strain amplitude.Soil stiffness properties agree well with those obtained based on laboratory tests.The material damping computed from acceleration records was however much higher than that independently measured in laboratory tests.Pore pressure buildup was found to affect shear wave velocity in the soil and weaken soil stiffness.