上海地区冻融后暗绿色粉质粘土动本构关系与微结构研究

Study on dynamic constitutive relation and microstructure of melted dark green silty soil in Shanghai

摘要: 以上海复兴东路越江隧道江底旁通道冻结施工中的原状和冻融作用后的暗绿色粉质粘土为研究对象,运用CKC循环三轴仪,采用不同的频率来摸拟行车荷载进行室内动三轴试验。通过室内试验得出了特定围压下不同动荷载频率作用下的暗绿色粉质粘土在冻融前后的动应力–动应变关系式,得到了土体的最大动弹性模量、最大动应力及最大动剪切模量随动频率的变化而变化的规律,并在此基础上结合该土体冻结前和冻融后的2000倍微结构电镜扫描图片,进一步对比分析了这种土体冻融后动力特性变化微观机理。试验结果显示该层土体经冻融作用后最大动应力有较大削弱,并且随着动荷载频率的加大冻融后的该土体最大动应力降低愈严重。

Abstract: Through lab tests on melted and common dark green silty soil of the passway in Shanghai Fuxing East Road Tunnel by using the typical triaxial test machine-CKC,their dynamic stress and stress-strain relations with different frequencies were studied.In addition,the maximum values of dynamic elastic modulus,dynamic stress and dynamic shear modulus of the silty soil were educed.Moreover,through the contrast analysis of the microstructure pictures,the maximum dynamic stress of this kind of soil would decline after being frozen and melted.