STONE COLUMNS

STONE COLUMNS

Stone columns are generally installed in weak soils such as soft cohesive or organic materials, inorganic silts and silty sands. The purpose of a stone column is to reduce settlement to acceptable or specified criteria and improve safe bearing capacity. The vibroreplacement method of installation uses a vibrator sunk to a preselected depth. Upon withdrawal the vibrator leaves a hole of slightly greater diameter that is immediately filled with gravel fill graded to between 0.5 and 3 inches. Once filled, the vibrator again penetrates to a preselected depth and displaces the gravel backfill laterally into the surrounding soil. It also compacts the soil and gravel beneath the vibrator tip. The result is a non-regular but reasonably cylindrical stone column. Column diameter will vary usually between two and three feet depending mainly on the strength characteristics of the surrounding soil.

VIBRATORY COMPACTED STONE COLUMNS

A vibratory compacted stone column is used to reduce settlement in weak bearing soils to acceptable or specified criteria and/or to improve bearing capacity. The column drilled into the soil is partially filled with aggregate base course that is then compacted using the vibratory probe method. This process of filling with aggregate base course and compaction using the vibratory probe continues until the column is completely filled.