埋深对银川黄河冲积平原砂土动剪切模量比和阻尼比影响的试验研究

Experimental Study on Influence of Buried Depth on Dynamic Shear Modulus Ratio and Damping Ratio of Sand in Yellow River Alluvial Plain in Yinchuan

摘要: 动剪切模量和阻尼比是两个反映土动力特性的重要参数，直接影响着土层地震反应分析的结果。本文针对银川平原四个试验钻孔所取的36个砂土试验样开展共振柱试验，得出： G_d/G_max随着γ的增大而减小，λ随着γ的增大而增大。当γ>1×10^-5 时，随着各钻孔砂土层粒径由粗到细，G_d/G_max由大到小变化，相同土类的G_d/G_max总体上随着深度的增加而增加；当 γ>5×10^-5 时，随着各钻孔砂土层粒径由粗到细，阻尼比λ由小到大变化，相同土类的阻尼比λ总体上随着深度的增加而减小。通过拟合不同γ下 、G_d/G_max与埋深的关系曲线，得到了不同γ下G_d/G_max 、λ 与埋深的拟合公式及拟合参数，在实际工程中有一定的参考价值。

Abstract: Dynamic shear modulus and damping ratio are two important parameters to reflect dynamic characteristics of soil, which directly affect the results of seismic response analysis of soil layer. In this paper, resonance column tests were carried out on 36 sand samples taken from four test boreholes in Yinchuan Plain. It is concluded that G_d/G_max decreases with the increase of γ , while λ increases with the increase of γ . When γ>1×10^-5 , with the increase of burial depth, the particle size of sand layer in each drill hole changes from coarse to fine, and G_d/G_max changes from large to small, and G_d/G_max of the same soil type increases with the increase of depth. When γ>5×10^-5 , with the increase of depth, the diameter of sand layer in each borehole changes from coarse to fine, and the damping ratio λ changes from small to large, and the damping ratio λ of the same soil decreases with the increase of depth. By fitting the relation curves of G_d/G_max , λ and burial depth under different γ conditions, the fitting formula and fitting parameters of G_d/G_max, λ and burial depth under different γ conditions are obtained, which has certain reference value in practical engineering.