In many countries in the world, especially Egypt, the possibility of damage to structures by soft ground constitutes a severe problem. Several methods are now available to overcome the problem of large settlement by improving the engineering properties of soft ground. One of the widely used techniques in improving the soft soil properties is preloading, in which the ground is loaded with uniformly distributed surface load prior to construction of the intended structure for a certain period of time. As large and powerful computing facilities become available, the need grows for numerical techniques that efficiently and accurately model the complex behavior of soft soil due to preloading. The target of the present paper is to present an appropriate numerical model that explains the preloading technique based on the results of an experimental study. A numerical procedure is proposed to predict the response of soft ground under preloading. Biot theory of consolidation with critical state soil model is used in solving the preloading problem. The model is then incorporated into a finite element program to solve the preloading problem. The applicability of the computational procedure is checked by comparing the numerical results with the experimental ones. The comparison indicates good agreement.
In the last few decades there has been growing demand for construction of civil engineering projects on sites underlain by thick strata of soft cohesive soils. The geological and previous loading history of the site and details regarding subsoil types, stratification, strength, and compressibility characteristics are of relatively greater importance for successful use of preloading techniques than they are for other alternatives. The decision as to whether or not preloading is to be employed depends on a number of main factors. These factors are; compression characteristics of soil, pore water pressure, soil permeability, and secondary consolidation.
