This research is a field study of bearing capacity and reaction modulus of the improved soil bed based on the new method of gravel impact compaction piers. Based on this, at the same time with soil improvement operations, a part of the Persian Gulf Science and Technology Park complex located in the 525-hectare site of Bushehr port was prepared. Then two experimental areas in and out of the improvement area and field experiments were performed. Soil improvement operations were performed in order to strengthen the upper layer of very loose upper silty sand soil with an average thickness of 3 meters against liquefaction. Based on this improvement plan, the bed of silty sand soil using the method of gravel impact compaction piers in a triangular network with a side length of 2.1 meters, nominal diameter of the base equal to 0.6 meter, extended diameter of 0.75 meter, and the average length of the foundations was equalized to 3 meters. In the present study, the behavior of a group of 3 separate gravel impact compaction piers (outside the improvement area) and a group of 3 gravel impact compaction piers in the n-network of foundations (within the improvement area), as well as soil behavior in conditions before and after soil improvement, were compared. Plate load test, pier loading test, and standard penetration test were among the field tests. Bearing capacity and reaction modulus of bed soil, piers, and composite soil were among the parameters studied in this study.
In general, the comparison of the results obtained from the evaluation of bearing capacity and soil reaction modulus at the soil location between piers and pier top in the two experimental groups of piers shows that the values of the results of the group of 3 gravel impact compaction piers outside the area Improvement is less than peer values in the group of 3 gravel impact compaction piers within the improvement area. Thus, the ultimate stress of the pier top and soil between the piers in the improvement ar