Answer by Rakshita Nagayach:
For the compaction of sand, various field equipments such as vibratory hammers, smooth-wheeled or grid-wheeled vibratory rollers, sheep-foot rollers, etc. are widely used. As per compaction is to be done, the less air and water the sand contains, the smaller the void, the firmer the sand mass would be.
The energy produced by the vibrations is absorbed by the soil, leading to compaction. Under the influence of these vibrations the inter-granular friction is overcome for a time. During this period, under the influence of gravity and complete stress relief, the soil particles rearrange themselves into a more compact arrangement. The vibrations move through the material, setting the particles into motion and moving them closer together for the highest density possible. Below is a picture of deep sand vibrator:
As vibration of the sand mass ensures highest possible density, it is better than other methods.
Hope this helps!