等压固结条件下湘江饱和砂土动力特性研究

STUDY ON DYNAMIC CHARACTERISTIC OF SATURATED SAND OF XIANGJIANG RIVER UNDER CONDITION OF ISOTROPIC CONSOLIDATION

在大量的动三轴试验基础上,研究了等压固结条件下湘江饱和砂土振动孔隙水压力、应力应变滞回圈以及应力路径的发展变化规律。研究结果表明:孔压发展变化过程与土体的剪胀、剪缩密切相关;孔压与轴向动应变之间的变化关系显示饱和砂土具有明显的各向异性;从孔压与滞回圈面积累积之和的关系看,孔压的增长伴随着能量的损失;对于围压较大的情形,用ExpAssoc函数进行拟合效果较好。隧振次增加应力应变滞回圈也在发生变化,第一阶段滞回圈呈倒置的帽子形,第二阶段呈菱角形状。在振动初始阶段,应力路径基本上呈倾斜的直线变化;随孔压的增加,加载和卸载两条应力路径逐渐分开,呈纺锤形。

Based on a lot of triaxial experiments, changes in excess pore-pressure, stress and strain ring and stress path of saturated sand of Xiangjiang River are studied under condition of isotropic consolidation and vibration. The results show that excess pore-pressure generation and dissipation is closely related to sand dilatancy. The relationship between excess pore-pressure and dynamic vertical strain indicates that saturated sand is evidently anisotropic. It is also concluded that increase in excess pore-pressure would consume energy from the relationship between excess pore-pressure and sum of stress and strain ring area. When the confining pressure on the specimens becomes larger, it would be better to use ExpAssoc function to simulate the pore pressure than using other function. With the vibration time increasing, the stress and strain ring would change in shape. It is like a cap with its top downward in the first phase, and then it is like a water chestnut in the second phase. At the beginning of vibration, stress path is almost a slanted beeline in shape. And with increase in excess pore-pressure, stress paths of loading and unloading gradually separate like a spindle.