vibroflotation

Vibroflotation, also known as vibro-replacement, is a geotechnical ground improvement technique used to densify loose granular soils and, in some variants, to form columns within the soil. The method relies on a vibroflot, a vibrating probe mounted on a crane and driven into the ground. The vibrator emits high-frequency vertical and lateral motions that rearrange soil particles, expelling fines and increasing soil density around the probe. In grout-column versions, the probe excavates a small cavity as it penetrates and cementitious grout is pumped into the cavity to create a rigid soil column. This combination of densification and, when used, grouting can improve bearing capacity and reduce settlements for shallow and deep foundations.

Operation and variants have two main aims. In densification, the probe is repeatedly advanced and withdrawn within a grid or pattern to densify the surrounding soil, expanding a compacted zone that supports structures. In vibro-replacement, the bore created by the vibrating probe is filled with cementitious grout to form discrete, load-bearing columns, which act as a skeletal reinforcement.

Equipment and conditions of use vary, but typical setups involve a vibroflot connected to a power unit and crane for positioning. The technique is widely used for foundations, piers, cofferdams, and other structures built on soft or loose granular soils, especially sands and gravels, and in settings where pile driving is undesirable or expensive.

Limitations include limited effectiveness in cohesive soils, potential pore-pressure buildup, noise and vibration concerns, and the need for suitable access and groundwater management. Proper geotechnical evaluation is essential to determine feasibility and design parameters.