Which densification method can achieve depths of about 30 ft using 30 ton weights and 100 ft drop heights?

Which densification method can achieve depths of about 30 ft using 30 ton weights and 100 ft drop heights?

• A. Plate compaction
• B. Rammer
• C. Dynamic compaction
• D. Vibratory plate compactor

Answer: (C)

Dynamic compaction uses a heavy drop weight released from a significant height to impart energy into the ground, causing soil particles to rearrange and air voids to be expelled. With a 30-ton weight dropped from about 100 ft, that energy can propagate deep enough to densify soil to depths on the order of 30 ft. This approach is specifically aimed at deep, wide-area densification, especially in granular soils where the energy can travel through the soil mass and compact deeper layers beyond the surface. Plate compaction and vibratory plate compactors rely on surface vibration or static load and are effective only at shallow depths, typically just a few feet. A rammer applies percussive blows as well, but its impact depth is also relatively shallow, often only up to a few feet. Hence, for achieving deep densification around 30 ft, dynamic compaction is the appropriate method.

Dynamic compaction uses a heavy drop weight released from a significant height to impart energy into the ground, causing soil particles to rearrange and air voids to be expelled. With a 30-ton weight dropped from about 100 ft, that energy can propagate deep enough to densify soil to depths on the order of 30 ft. This approach is specifically aimed at deep, wide-area densification, especially in granular soils where the energy can travel through the soil mass and compact deeper layers beyond the surface.

Plate compaction and vibratory plate compactors rely on surface vibration or static load and are effective only at shallow depths, typically just a few feet. A rammer applies percussive blows as well, but its impact depth is also relatively shallow, often only up to a few feet. Hence, for achieving deep densification around 30 ft, dynamic compaction is the appropriate method.