非饱和土二维固结简化计算的研究

Simplified computation of two-dimensional consolidation of unsaturated soils

针对较高饱和度的非饱和土二维固结问题展开研究。对于较高饱和度的非饱和土,如饱和度Sr>80%时,将孔隙中气、水近似地看作可压缩的气、水混合流体后,非饱和土近似为土骨架和混合流体的二相土。考虑混合流体的压缩性,建立混合流体的连续方程。联立平衡方程和混合流体的连续方程,求出应力-应变和混合流体压力;再建立水连续方程求解水压力,继而求出气压力、吸力等。算例表明:加载和消散过程中,混合流体与水压力变化基本一致,气压的作用并不大;地基变形过程与高速公路填筑过程中地基变形发生规律一致。说明该简化方法是合理的,并促进了非饱和土固结变形计算走向实用化。

The two-dimensional consolidation problem of unsaturated soils is studied. If water and air in the pores can be regarded as a mixed fluid in unsaturated soils with St〉 80 %, the deformations of unsaturated soils become the consolidation process of two-phase with soil skeleton and mixed fluid. Regarding the compressibility of the mixed fluid in pores, mixed fluid continuity equations are established. Then the stress-strain and mixed fluid pressure can be computed by mixed fluid continuity equations and balanced equations. If the suction and pore-air pressure are required, the water continuity equation should be established first to compute the pore-water pressure. A numerical example shows that the pore-air pressure is a minor factor in the consolidation process of unsaturated soils because the changing of the mixed fluid pressure is consistent with that of pore-water pressure; the deformation process is similar to that of embankment construction. Therefore, the approach is reasonable and very important to pragmatize computation of consolidation deformation.