My field of study is in geotechnical engineering with emphasis in the area of slope stability, retaining walls, and constitutive modeling. I have participated in the design of several large concrete and earth dams in Europe, Asia, and Latin America. I also performed and direct numeerous geotechnical investigations and analyses of earth failure mechanisms including landslides, subsidence, slope failure, settlement, soil collapse and expansion heave. In addition to the above functions, I perform engineering analyses for the design of foundations, retaining walls, earth structures, slopes, embankments, and the evaluation of seismicity.Since 1989, I have been studying the effects of rainfall on the surficial stability of slopes in Southern California. My studies suggest that permeability plays an important role in the surficial stability of slopes, and that for coarse soils the factor of safety can be seriously underestimated using conventional procedures. In the area of constitutive modeling, my research has concentrated on the mechanical stability of saturated and partly saturated soils, the experimental determination of yield and plastic potential surfaces, and on the elastoplastic modeling of anisotropic behavior. My research has shown that static liquefaction can be seen as an instability phenomena, and that experimental data supports the suitability of stability conditions based on the theory of plasticity.