动扭剪荷载条件下黄土动强度特性试验研究

Experimental Research on Dynamic Strength Characteristics of Loess under Dynamic Torsional Shears

在各地区地震频繁发生,黄土地基安全问题严重威胁各项工程建设的情况下,本文利用动扭剪仪,通过对不同地区(兰州、洛川、杨凌、巩义)黄土的动强度特性的研究表明:各地区黄土动强度特性大小顺序分别为杨凌黄土>巩义黄土>洛川黄土>兰州黄土,地理空间分布上有一定规律,即从西北向东南方向增强;试验所用的四种黄土的试验曲线介于拉德-邓肯破坏条件和屈瑞斯卡提出的破坏条件之间,其动强度值均大于邢义川、松岗元、摩尔-库仑破坏条件所对应的强度函数曲线;黄土的黏聚力Cd和内摩擦角φd均随振次的增大都呈减小趋势,其中黏聚力Cd的急剧降低是黄土扭剪破坏的主要原因。

Engineering construction is increasingly threatened by loess ground when earthquake happens more frequently.In this paper,the behaviors of dynamic strength of the loess in different regions（Lanzhou,Luochuan,Gongyi,Yangling） are studied with the dynamic torsional shear tests and the research findings show that： The dynamic strength characteristics of the loess in different regions are Yangling,Gongyi,Luochuan,Lanzhou,the main trend tends to rise from the northwest to the southeast.The dynamic strength point is located in the place between the Lade-Duncan curve and the Tresca curve.Xing Yichuan,Matsuoka-Nakai and Mohr-Coulomb failure conditions are less than the curve of experimental values;the dynamic strength indexes cohesion Cd and friction angle φd all decline as the cycle time increases,but the friction angle changes less than the cohesive strength.