Soil Mechanics and Theorems of Limit Analysis

An attempt is made to exhibit the plastic limit theorems in terms more familiar to the civil engineer. The interpretation of a continuous velocity region as the limiting case of infinitely many rigid blocks separated by surfaces of discontinuity provide an excellent technique for obtaining energy dissipation needed for upper bound calculations on plastic limit load. Similarly, the intuitive approach of imagining a pinconnected truss to support loads is shown to provide an excellent technique for obtaining lower bounds. Also a graphical procedure is introduced to eliminate much of the tedium associated with the construction of a stress field. The problems of the loaded truncated wedge and the wedge under unilateral pressure are treated as illustrative examples. Then the general strip foundation is solved. Upper and lower bounds are plotted and are seen to be rather close. Friction effects on the bearing capacity of foundations are also discussed.