Dynamic Compaction (DC) has been used as soil improvement techniques for decades. The technique involves subsequent drops (tamps) of heavy weights onto the ground surface to densify the underlying soil. The technique is widely spreading because of its economical advantage and technical ease. DC is relatively cheap since no soil replacement or material addition is required. In addition, the equipment used for the process is simple. Therefore, shortly after the successful application of the DC on cohesion-less soils the technique has been extended for cohesion soils.;Usually, a crane is used to lift the tamper; Tamper weight ranges from 10 to 20 tons and drope height ranges from 10 to 20 meters. Then, the tamper is released to free fall and strike soil surface. The process is done in rounds. At each round, tamping takes place over a pre-defined grid. A decision for a second round of tamping is made when the depth of the induced crater is greater than the tamper height. A shifted grid is used for the second round of tamping after soil surface is bulldozed. In-situ tests (CPT or SPT) to estimate soil properties after compaction and to decide if further treatment is needed.;Empirical guidance on the zone of influence (e.g., the depth of improvement and the degree of improvement) as a function of impact energy has been summarized in the literature. Furthermore, there have been a limited number of numerical simulation techniques that were developed specifically for modeling the impact phenomenon of dynamic compaction on soil medium. However, the past numerical simulations were limited to the use of a simplified elastic perfectly plastic model to represent soils, which may not capture the highly plastic and nonlinear behavior of cohesive soils under dynamic compaction.;The work presented throughout this report is concerned with studying the dynamic compaction in cohesive soils. Two-dimension and three-dimension finite element models were developed. Modified Cam-Clay soil constitutive model, which captures the highly nonlinear behavior of soil, has been used throughout the presented work. A parametric study by mean of changing each Cam-Clay parameter at a time was conducted. Correlation between the soil properties and tamping energy per blow and the zone of influence is presented. In addition the amplitude of the wave velocity, which is propagating outward the compaction spot, is estimated as a function of tamping energy and Cam-Clay parameters. Utilizing the three dimensional model, the interaction between nearby drops was studied. Finally design charts for a step-by-step design methodology for DC in cohesive soils were presented.
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