Laboratory vacuum dynamic consolidation tests were performed to study the effect of dynamic impact loads on the shear strength characteristics of dredger fill. The results revealed that the shear strength increased with the increase in the number of blows. The relationship between the increase in the shear strength and the soil structure was analyzed through scanning electron microscopy and mercury intrusion porosimetry. The structure collapsed progressively and the larger inter-aggregate pores were affected the most. Considering pore evolution, the pore size distribution was primarily unimodal, and the variations in porosity and shear strength with the blow count were the same. Thus, the shear strength of dredger fill is influenced by its structure. On average, five blows ensure high compaction efficiency.