摘要
天津滨海地区软土层深厚且沉积时间短,故蠕变特性显著,修建于其上的各类型建筑物沉降历时时间长,准确预测地基的最终沉降量成为工程设计的难题.针对天津滨海软土开展了一系列三轴固结蠕变试验,得到了不同围压与应力水平下的应变-时间曲线.提出了与围压和应力水平相关联的Merchant模型参数的确定方法,揭示了模型中3个参数在相同围压下随着应力水平的增大而近似呈线性减小的规律.以此为基础,建立了反映时间效应的天津滨海软土三维非线性黏弹性蠕变本构模型,开发了有限元子程序.与实际工程的观测资料对比表明,该蠕变模型能有效模拟不同施工阶段路堤沉降量的非线性发展过程与沉降速率的变化规律.
The coastal area of Tianjin is covered with a deep layer of soft soil.The soft soil has experienced a short time of deposition and shows significant creep properties.Besides,the settling time of buildings constructed on the soft soil was long,so it is important to accurately predict the final settlement of soft ground.A series of triaxial consolidating creep tests were carried out,and strain-time curves under different confining stresses and stress levels were acquired.A method of determining Merchant model parameters related to confining stress and stress level was established.Three parameters of Merchant model were all reduced linearly with the stress level under the same confining stress.On this basis,a three-dimensional non-linear viscoelasticity constitutive model which reflects time effect was built.Subroutine of finite element was also developed.Compared with prototype observation data,the creep model can effectively estimate the nonlinear development of settlement and the change rule of settling rate of embankment in different construction stages.
引文
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