Vibroflotation and Terra-Probe Comparison

The most widely used techniques for deep vibratory compaction of cohesionless soils are Vibroflotation and Terra-Probe. The Vibroflotation process consists of penetrating the soil with a horizontally vibrating probe and simultaneously saturating and vibrating the soil as the probe is extracted. The Terra-Probe process consists of driving and retracting a 30-in.(760-mm) diam open-ended steel pipe with vertical vibrations induced by a vibratory pile driver. Three test patterns with different probe spacings were compacted with 100-hp Vibroflot probes and three test patterns were compacted by Terra-Probe. Each test pattern was compacted to a depth of 35 ft (11m). Static cone penetration tests and standard penetration tests were conducted in each test pattern before and after compaction. The average change in relative density within each test pattern was obtained by measuring the volume of sand added and the subsidence of the ground surface. The test results indicate that Vibroflotation compacted a greater volume of soil per probe penetration than Terra-Probe, the latter, however, working faster.