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Title:: Experimental Study on Dynamic Elastic Modulus and Damping Ratio of Undisturbed Loess Based on Microstructure

作者:: 刘富强¹; 2; 3; 钟秀梅²; 3; 刘钊钊¹; 2; 3; 梁收运¹; 高烨¹; 王申宁¹; (1.兰州大学土木工程与力学学院,甘肃兰州 730000; 2.中国地震局兰州地震研究所,甘肃兰州 730000; 3.中国地震局黄土地震工程重点实验室,甘肃兰州 730000)

Author(s):: LIU Fuqiang¹; 2; 3; ZHONG Xiumei²; 3; LIU Zhaozhao¹; 2; 3; LIANG Shouyun¹; GAO Ye¹; WANG Shenning¹; (1.College of Civil Engineering and Mechanics,Lanzhou University,Gansu 730000,Lanzhou,China)(2.Lanzhou Institute of Seismology,China Earthquake Administration,Gansu 730000,Lanzhou,China)(3.Key Laboratory of Loess Earthquake Engineering,China Earthquake Administration,Gansu 730000,Lanzhou,China)

Keywords:: scanning electron microscope; dynamic triaxial test; dynamic characteristics; structural characteristics

摘要:: 黄土的细观结构对其非线性动力参数具有重要影响。选取不同地区的典型原状黄土进行室内动三轴试验和扫描电镜(SEM)试验,利用PCAS孔隙图像识别与分析系统统计分析SEM图像,获取了黄土的孔隙细观结构参数,分析了孔隙细观结构参数与初始动弹性模量和阻尼比的关系。结果表明:初始动弹性模量随着土体平均孔隙直径、表观孔隙率、分形维数和概率熵的增大而减小,其中平均孔隙直径和分形维数对初始动弹性模量的影响较为显著,表明土体内孔隙的大小及其排列对土体的动弹性模量具有明显的影响; 而阻尼比均随着土体平均孔隙直径、表观孔隙率、分形维数和概率熵的增大呈非线性增大,其与表观孔隙率和分形维数具有明显的相关性,表明孔隙数量及其排列形态对土的阻尼比影响较为明显。

Abstract:: The structural characteristics of loess are important influence factors of dynamic elastic modulus and damping ratio.In this paper,the typical undisturbed loess samples in different regions are selected for dynamic triaxial tests and SEM tests.We statistically analyzed SEM images to obtain microstructure parameters by using PCAS pore image recognition and analysis system,and studyed the relationship between pore mesostructure parameters and initial dynamic elastic modulus and damping ratio of loess.The results show that the initial dynamic elastic modulus decreases with the increase of the average pore diameter,fractal dimension,probability entropy,and apparent porosity of loess.Among these four parameters,the average pore diameter and fractal dimension have a significant effect on the initial dynamic elastic modulus of the loess,which shows that the size and arrangement of pores are the main influence parameters.However,the damping ratio increases nonlinearly with the increase of apparent porosity,fractal dimension,the average pore diameter,and probability entropy of the loess,which has an obvious correlation with apparent porosity and fractal dimension.It shows that the number of pores and the arrangement of pores have an obvious influence on the damping ratio of the loess.