变围压条件下饱和红黏土动力特性研究

Dynamic characteristics of saturated red clay under variable confining pressure

真实路基填料的应力路径十分复杂,常规循环三轴动力试验在常围压条件下进行,无法模拟真实路基填料的受力状态。基于此,为了更好的模拟交通荷载下路基层的真实受力状态,采用GDS循环三轴系统对赣南地区的路基红黏土分别进行了变围压(VCP)和常围压(CCP)下的循环三轴试验,在三种应力状态下,即相同的最大应力状态,相同的平均应力状态,相同的初始应力状态,对比分析了变围压对红黏土孔压发展、回弹模量和轴向累积变形的影响。试验结果表明,各应力状态下变围压都导致了孔压累积的增加。对于相同的最大应力状态,变围压下试样回弹模量较低,累积变形较大,而在相同的最小应力状态下则结论相反。对于相同的平均应力状态,变围压对红黏土长期变形特性的影响可忽略。

The stress path of real subgrade filler is very complicated,andthe traditional cyclic tri-axial dynamic tests are conducted under constant confining pressureand they can’t stimulate load-bearing states of real subgrade filler.Here,in order to simulate real stress states of roadbed under traffic load,cyclic tri-axial tests were conducted for saturated red clay atsouthern area of Jiangxi province under constant confining pressure(CCP)and variable one(VCP),respectively.Under three stress states of the same maximum stress state,the same mean one and the same initial one,effects of variable confining pressure on pore pressure development,rebound modulus and axial cumulative deformation of red clay were contrastively analyzed.The results showed that variable confining pressure cancauseincrease in pore pressure accumulation under three stress states;for the same maximum stress state,specimens’rebound modulus is lower under variable confining pressure,their cumulative deformation is larger;for the same minimum stress state,the situation is opposite;for the same mean stress state,effects of variable confining pressure on long-term deformation characteristics of red clay can be neglected.