砂土动剪切模量比和阻尼比共振柱试验误差研究

Resonant column test error analysis for dynamic shear modulus ratio and damping ratio of sand

摘要:

为掌握动剪切模量比和阻尼比非线性试验误差及现有共振柱试验水平，设计了普通与高级两组典型试验，采用单台共振柱仪研究了砂土动剪切模量比和阻尼比试验误差的分布特征和基本规律.试验和分析结果表明：两类型组动剪切模量比和阻尼比非线性试验数据在不同剪应变特征点均服从正态分布，且离散性指标均呈现出一致的规律性；两类型组试验均值十分接近，但普通组的置信区间明显大，其变异系数是专业组的5倍；无论普通组还是专业组，模量比变异系数明显小于阻尼比变异系数.就目前共振柱试验水平而言，技术熟练试验人员所完成的砂土动剪切模量比和阻尼比的试验精度一般可以满足要求，其他情况下试验误差不可忽视，需增加平行试验次数，提高试验技术.

Abstract:

To acquaint the testing errors of nonlinear dynamic shear modulus ratio and damping ratio using the prevailing resonant column technique, two typically representative test groups, i.e., a general group and a professional group, are designated. The error distribution and the relevant statistic characteristics of dynamic shear modulus ratios and damping ratios of sand are systematically studied on a single resonant column apparatus. The testing results indicate: (1) the test data of nonlinear dynamic shear modulus ratio and damping ratio of the two groups are normally distributed at different characteristic shear strains, and the variability indices are closely consistent for the two groups; (2) the mean values of the two groups are similar while the confidence interval of the general group is particularly larger than that of the prefessional group with a coefficient of variance 5 times larger than that of the professional group; (3) the coefficient of variance of shear modulus ratio is remarkably smaller than that of damping ratio. On the current testing technique of resonant column apparatus, the test accuracy of shear modulus ratio and damping ratio on sandy samples by an experienced individual can be quite satisfactory but on the other cases the testing error cannot be neglected that parallel tests should be performed and the testing skill of the operators should be improved.