考虑颗粒形状影响的砂土剪切波速研究

Experimental study on sand shear wave velocity considering the influence of particle shape

天然砂土的形状往往差异较大,为研究剪切波在不同形状砂土中的传播特性,首先选取3种不同形状的石英砂开展颗粒形状分析;其次,采用安装有弯曲元系统的三轴仪对砂土试样进行剪切波速测试及三轴剪切试验,获得3种石英砂的剪切波波速及其临界状态线。试验结果表明:(1)在相近的孔隙比和围压下,随着整体规则度OR降低,石英砂试样的剪切波波速Vs逐渐增大;(2)基于临界状态土力学中的状态参数,提出计算石英砂剪切波波速的归一化模型,并采用文献中的数据对模型进行验证,发现其预测精准度较好;(3)在上述模型的基础上,提出采用剪切波波速预测不同形状石英砂剪切特性的新方法。上述成果为用原位剪切波波速判别复杂形状砂土层的剪切失稳特性提供依据。

The shapes of natural sands often vary greatly.To study the characteristics of shear wave propagation in sand with different shapes,quartz sands with three different shapes were first selected for particle shape analysis.Secondly,a triaxial apparatus equipped with a bender element system was used to conduct shear wave tests and triaxial shear tests on sand samples,obtaining the shear wave velocities and critical state lines of the three types of quartz sands.The test results indicate that:(1)under similar void ratios and confining pressures,the shear wave velocity(Vs)of the quartz sands gradually increases as the overall regularity(OR)decreases;(2)based on the state parameter in the framework of the critical state soil mechanics,a new model that allows unified characterization of shear wave velocity for quartz sand was developed,and it shows a satisfactory predictive performance by using the data from the literature;(3)on the basis of the above model,a new method using the shear wave velocity was proposed to predict the shear response of quartz sands with different shapes.The outcomes from this study provide a basis for evaluating the shear instability of complex-shaped sandy soil layers using the in-situ shear wave velocity.