【摘要】 不均匀地层中超静孔压的扩散、重分布过程会导致孔隙水集中渗流累积至局部区域,导致该区域土体强制吸水,从而引发剪胀性砂土边坡地震后侧向流动变形甚至失稳。通过分析边坡流动变形过程中砂土的应力路径特征及强制吸水条件下的体变平衡条件,指出预测剪胀性砂土边坡流动变形的关键是描述砂土保持常剪应力和当前峰值应力比时的剪胀特性和震后再固结体变特性。通过常偏应力下的三轴剪切吸水试验,观察了砂土在流动变形过程中的吸水量与剪应变发展的关系,给出了基于强制吸水体变预测流动剪应变的状态剪胀模型。基于剪切后再固结试验,得出了再固结体变的变化规律和数学描述。基于所提出的机制和数学描述,给出了基于有限差分法的边坡流动变形发展过程直至失稳破坏的模拟方法。更多还原

【Abstract】 The diffusion and redistribution of the excess pore pressure in inhomogeneous strata lead to pore water concentration in certain local areas, where the soils are compelled to absorb water, causing continuous flow deformation of slopes composed of dilative sand both during and after earthquakes. By studying typical stress paths and volumetric strain component constraints of sand during flow deformation, it is found that the stress-dilatancy under shearing with constant deviator stress along the peak stress ratio and post-earthquake reconsolidation volumetric strain are the two key issues in modeling the post-earthquake flow deformation and failure. The triaxial compression tests under constant deviator stress are performed to observe the relationship between water absorption and shear strain development of sand, and a state-dependent dilatancy model is proposed to predict the large shear strain according to the volume of absorbed water. A description of reconsolidation volumetric strain is also developed based on the consolidation tests on specimens after large shearing. A procedure for modeling the development of the post-earthquake flow deformation is proposed based on the proposed mechanism, mathematical descriptions and simplified finite difference method to simulate pore water seepage.更多还原