摘要
土的动力学参数是地震安全性评估的重要依据,为了研究粉土在振动荷载下的变形和破坏行为,以郑州地区粉土为研究对象,利用GCTS三轴振动仪对重塑土样进行分级循环加载的动三轴试验,分析粉土在不同含水率和围压下的动剪切模量和阻尼比变化规律.结果表明:粉土的动剪切模量随着动剪应变的增大逐渐减小,曲线速率则随着动剪切应变的增大减缓,最后趋向稳定,含水率和围压不改变粉土动剪切模量-动剪切应变曲线的变化形态;粉土的动剪切模量随着围压的增加而增大,随着含水率的增加而减小;低围压时,围压增加对土体动剪切模量的增大作用尤为显著,并且深度较大的土样具有抵抗破坏的天然优势;粉土的阻尼比随着含水率的增加而增加,随着围压的增加而减小;阻尼比的大小与土体所处深度及周围压力有关,围压越大,阻尼比越小;围压对阻尼比的影响受含水率影响,含水率越高,围压对阻尼比的影响越明显.
Abstract
The seismic safety assessment heavily relies on soil's dynamic parameters.To investigate how silt behaves and fails under vibrational loads,a dynamic triaxial test involving graded cyclic loading was conducted on soil samples from Zhengzhou using the GCTS triaxial vibration equipment.This analysis focused on how the dynamic shear modulus and damping ratio of silt vary with different water contents and confining pressures.The results are as follows.As dy-namic shear strain increases,the dynamic shear modulus of silt decreases gradually.This decrease slows down as the strain continues to rise,eventually reaching a stable state.Notably,neither water content nor confining pressure alters the overall shape of this modulus-strain curve.Higher confining pressures boost the dynamic shear modulus of silt,while increased water content has the opposite effect.At lower confining pressures,even small increases in pressure significantly enhance the soil's dynamic shear modulus,giving deeper soil samples a natural resilience against failure.Silt's damping ratio rises with water content but falls with increasing confining pressure.The damping ratio's magnitude is influenced by soil depth and surrounding pressure,where higher confining pressures result in lower damping ratios.The impact of confining pressure on damping ratio is also influenced by water content;the higher the water content,the more pronounced this pressure effect becomes.
维普
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