In this paper, physical modeling tests are conducted to study some aspects of the Dynamic compaction method. The loose models are prepared with dry sand. Four cylindrical tampers with different weight and cross section areas are used for compaction of the models and dropped from various heights. Strain gage type total stress measuring sensors are placed at different levels inside the model to measure the transferred vertical stresses due to collision of the tamper with the surface of the models. The typical stress time histories are presented. Improvement depth and crater depth and diameter created on the model surface are studied, among the various parameters affecting the phenomena. Using the results of the tests, a relation is proposed for the improvement depth which has good agreement with the measured site results.    

Dynamic compaction (DC) is employed as a simple and economical method to improve weak soils in the last few decades. DC is usually applied for granular soils by falling a heavyweight (up to 40 tons) from a height (up to 40 m) at regularly spaced intervals. Significant issues in DC are the weight and height of the tamper, compaction pattern and the distance between tamping locations. Incorporated innovation in this paper is to introduce an analytical approach to optimize the compaction pattern and DC variables regarding regular constraints. The required energy for compaction is evaluated for square and diamond patterns. DC optimization is a non-linear and non-convex problem due to nonlinear equations in soil compaction behavior. Thus, a metaheuristic approach (Genetic Algorithm) is employed to find global optimum. The optimum answer presents the minimum compaction energy in each pattern. Results indicated that the maximum allowed values of tamper mass and the number of tamper drops were required to minimize compaction energy. The ratio of compaction energy at diamond pattern to square one was also found to be about 0.75 to 0.90 for the same compaction conditions.

Dynamic compaction (DC) is a popular soil improvement method that is extensively used worldwide. DC treatment design is usually carried out based on past experiences and empirical relations. To establish a rational design approach, all important factors affecting the DC process should be taken into account. In this paper, a finite element code is developed for modeling the impact behavior of dry and moist granular soils. The code is verified with the results of some centrifuge tests. Several analyses were conducted in order to study the effects of energy/momentum per drop, tamper base radius, and number of drops on compaction degree, compacted depth, and extension of the improved zone in the ground. The developed code has considerable capabilities to be used as a tool for designing Dynamic compaction treatments.

Dynamic compaction in urban areas has great potential to damage nearby structures and their occupants due to induced vibrations. One common approach to keeping these vibrations in a safe range is installing a barrier crossing the wavefronts. Previous studies have largely focused on evaluating the effectiveness of trench barriers in reducing continuous vibrations, while the efficiency of boreholes as an alternative approach with a lower volume of excavation has not been thoroughly investigated. This study uses ABAQUS software to compare the efficiency of borehole and trench barriers in reducing vibrations induced by the Dynamic compaction (DC) process using a 3D model validated by in-field study results. The study uses a row of hollow boreholes with varying diameters, depths, and center-to-center distances located at a fixed location from the tamping point to investigate the efficiency of borehole barriers based on their geometrical parameters. Open trenches with varying lengths, depths, and distances from the tamping point are also used for comparative investigations. The results indicate that the trenches have overall better performance than borehole barriers, However, properly designed boreholes can still reduce vibrations to an acceptable extent. Finally, the study presents design guidelines for further practical applications.

Dynamic compaction (DC) is a widely used soil improvement method in dry and/or saturated soils. The design of DC treatment is usually carried out based on the past experiences and empirical relations. In order to clarify the ambiguities in DC processes, numerical modeling of DC in dry granular soils has been considered using a Dynamic finite element code. Using the developed model, two design curves for determination of effective print spacing (distance between two neighboring drop points) in Dynamic compaction of dry sandy soils are proposed. A case history of Dynamic compaction project is analyzed and the obtained results show that the developed design curves have good capability for determination of print spacing