The design of dynamic compaction is largely based on experience. A review of the literature discovers that the base area of the tamper has not been considered in design and the tampers used in the published case histories all have a fiat base. This paper presents the results of a study to show that both size and shape of the base of the tamper are significant in soil improvement by dynamic compaction. Both theoretical analyses and laboratory model tests were carried out during this study.
The Dynamic Compaction (DC) technique has been implemented in many projects all over the world for densification of loose soils (e.g. Menard and Broise, 1975; Leonards et al., 1980; Lukas, 1980, 1986; Jessberger and Beine, 1981; Gambin, 1983; Mayne et al., 1984; Senneset and Nestvold, 1992; Chow et al., 1994). Improvement of hydraulically reclaimed lands is one of the major applications of this technique. The DC technique involves releasing a tamper from a specified height so that densification of soils at depth can be achieved. Upon the impact by the tamper, a crater is created with heave around the crater sometimes observed. The difference between the volume of the crater and the volume of heave is a reduction in the volume of soil, which represents the effectiveness of DC. In situ tests such as the cone penetration test (CPT) and the pressuremeter test (PMT) have been used to obtain soil strength profiles both before DC and after DC. Both depth and degree of improvement are generally derived from the results of these tests. A review of the literature discovers that the design of dynamic compaction has not properly considered the base area of the tamper. The design of dynamic compaction is largely based on experience.
