循环荷载下硅藻土应变和孔压特性  

Strain and Pore Pressure Characteristics ofDiatomite under Cyclic Loading

作　　者：姜煌辉 蒋军[1] JIANG Huanghui;JIANG Jun(College of Civil Engineering and Architecture,Zhejiang University, Hangzhou 310058, Zhejiang China)

机构地区：[1]浙江大学建筑工程学院

出　　处：《力学季刊》2019年第2期335-342,共8页Chinese Quarterly of Mechanics

摘　　要：针对嵊州硅藻土的高结构性及地基应力场的复杂多变,应用GDS动三轴仪进行不同围压和不同循环应力比下的不排水循环加载试验,分析应力-应变滞回曲线演化、应变累积特性、回弹特性及孔压特性.研究表明:循环应力比及围压对原状硅藻土应变和孔压的发展规律影响明显,随着循环应力比的增加,滞回曲线由线性状态转变为非线性状态,且逐渐向x轴倾斜,累计应变和回弹应变都随着循环应力比的增加而略微增加,但总应变基本小于2%;残余孔压比随循环应力比增大而增大,范围为0.1~0.5.并且存在一个临界循环应力比,其值随有效围压的增大而减小,范围为0.8~2.2,当循环应力比大于该值时,试样内部产生一个破裂面迅速发生破坏.在相同循环应力比下,试样的应变随着有效围压的增大而增大.In view of the high structural and complex stress field of the diatomite in Shengzhou, the undrained cyclic loading test under different confining pressures and different cyclic stress ratios was carried out by GDS dynamic triaxial apparatus to analyze the evolution law of the stress-strain hysteresis curve, strain accumulation and rebound characteristics. The research shows that the cyclic stress ratio and confining pressure have obvious influence on the development of strain and pore pressure of undisturbed diatomite. With the increase of cyclic stress ratio, the hysteresis curve changes from linear state to nonlinear state, and gradually tilts to the x-axis. Both the cumulative strain and the rebound strain increase slightly with the increase of the cyclic stress ratio, but the total strain is less than 2%;the residual pore pressure ratio increases with the increase of the cyclic stress ratio, and the range is0.1~0.5. And there is a critical cyclic stress ratio, the value of which decreases with the increase of the effective confining pressure,the range is 0.8~2.2. When the cyclic stress ratio is greater than this value, a crack surface is generated inside the sample and rapidly breaks. At the same cyclic stress ratio, the strain of the sample increases as the effective confining pressure increases.

关 键 词：应力-应变滞回曲线 回弹特性 残余孔压比 动三轴 硅藻土 

分 类 号：TU44[建筑科学—岩土工程]