This technique involves the construction of concrete columns with a bottom-feed, down-hole vibratory probe to transfer loads through weak strata to a firm underlying stratum.
A bottom-feed, down-hole vibratory probe is advanced through the weak strata to the underlying firm stratum. Granular bearing soils are densified by the vibrator. Concrete is then pumped through the bottom-feed tremie tube. The vibrator is raised and lowered several times within the bearing depth to construct an expanded base. The vibrator is then raised to the surface as concrete fills the void created by the vibrator during extraction. Typically, the vibrator also re-penetrates the top of the column to construct an enlarged head, which can be overlain by a geogrid reinforced soil relieving platform.
Vibro rigs can be fully instrumented with an onboard data acquisition system. Data from the system, such as amperage and lift rate, can then be recorded and displayed in real-time alongside specified target values on an in-cab monitor. This monitoring allows the operator to correct any deviations in real-time during the construction process to keep the vibro compaction within project specifications.