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The consolidation of unsaturated soil is of great significance to road engineering, soft foundation soil improvement, etc. Based on the one-dimensional consolidation theory of unsaturated soil proposed by Fredlund and Hasan, the governing equations for pore water pressure and pore air pressure in the soil are established. The initial conditions and a type of time-dependent mixed nonhomogeneous boundary conditions of single-layer unsaturated soil are presented which constitutes the solution of 1D consolidation of unsaturated soil. The homogenization of nonhomogeneous boundary conditions and the eigenfunction expansion method are adopted to derive exact analytical solutions in time domain for the dissipation of pore water pressure and pore air pressure in the soil. Finally, the method proposed in this paper is validated by comparison with published results, and several examples are used to analyze the effects of exponentially changing boundary conditions on the dissipation of pore water pressure, pore air pressure, and deformation of unsaturated soils. The results show that the speed of exponential change of pore pressure on the boundary or flux across the boundary has significant effect on the consolidation process of unsaturated soil.

A real-coded genetic algorithm is employed to develop a search approach for locating the noncircular critical slip surface in slope stability analyses. Limit equilibrium methods and the finite-element-based method are incorporated with the proposed search approach to calculate the factor of safety. Geometrical and kinematical compatibility constraints are established based on the features of slope problems to prevent slip surfaces from being unreasonable. A dynamic bound technique is presented to improve the search performance with more effective exploration within the solution domain. A number of examples are investigated that demonstrate the proposed search approach to be efficient in yielding accurate solutions to practical slope stability problems. The proposed search approach is stable and highly correlated with the results of independent analyses. Furthermore, this paper demonstrates the successful application of a real-coded genetic algorithm to noncircular critical slip surface search problems. Key words: genetic algorithm, critical slip surface, slope stability analysis, factor of safety. Resume : Un algorithme genetique est utilise pour developper une approche de recherche afin de localiser la surface critique de glissemeni non-circuiaire dans les analyses de stabilite de penle. Les methodes de l'equilibre limite el une methode basee sur les elements finis ont ete incorporees a l'approche de recherche proposee dans le bul de calculer le facteur de securite. Les contraintes de compatibilite geometriques et einemaliques sont etablies selon les caracterisliques des problemes de pente, et ce afin de prevenir que les surface de glissement deviennent deraisonnables. Une technique dynamique est presentee pour ameliorer la performance de la recherche avec des explorations plus efficace a l'interieur du domaine de la solution. Plusieurs exemples sont investigues afin de demontrer que l'approche proposee est efficace pour donner des solutions precises aux problemes pratiques de stabilite de pente. L'approche de recherche proposee s'avere etre stable, avec une forte correlation entre les resultats d'analyses independantes. De plus, cet article demontre l'application d'un algorithme genetique dans les problemes de recherche des surfaces critiques de glissement non-circulaires. Mots-des : algorithme genetique, surface critique de glissement. analyse de stabilite de pente. facteur de securite. [Traduit par la Redaction], Introduction A full slope stability analysis generally comprises evaluation of the factor of safety ([F.sub.s]) for the given slip surfaces and determination of the critical slip surface, which is associated [...]

The 2008 Mw7.9 Wenchuan earthquake in China caused widespread soil liquefaction and ground failures. A liquefaction case study of gently sloping ground at Yingxiu Town in the near-fault region is presented, which features its relatively thick deposits of sand-gravel mixtures, high soil stiffness, extremely intensive ground motion, large lateral spreading and severe damage of superstructure. The details of ground motion, site condition, field manifestations of liquefaction, subsurface soil profiles and field testing of shear wave velocities are presented. A conceptual binary mixture model is proposed to explain the gravel content effect on the stiffness and liquefaction resistance of gravelly soils. A preliminary liquefaction triggering evaluation method for gravelly soils is proposed by considering the gravel content correction of shear wave velocities based on the existing simplified procedure for typical sandy soils. The failure mechanism of the Baihua Bridge built at this site is explored, and the liquefaction-induced lateral spreading in down-slope direction might aggravate the failure process by imposing a large kinematic load on the piers besides the inertial forces transferred from the superstructure. [ABSTRACT FROM AUTHOR]