Wet Top Feed Stone Columns were invented in Germany in the early 1960’s. They are faster to install and need less sophisticated equipment than Dry Bottom Feed Stone Columns. However, the installation technique requires more experience than Dry Bottom Feed Stone Columns. Stone columns West Kowloon, Hong Kong.

Where to Use the Wet Top Feed Stone Column Method ?

• Where the compaction of sandy and gravelly layers is required and those layers are located above the water table. Compaction is generally better accomplished with the wet method than with the dry method, as the flushing water assists in compaction of the sandy soil around the column.
• Where particularly clean stone columns are required. The flushing water cleans the columns during installation.
• Wherever there are no contaminants in the soil and the soil is not a highly plastic clay leading to the problem of handling the mud in the process water.
• Where space is available for a 500 m2 (= 5000 ft2) settling pond.
• Where the installation crew has sufficient experience in the more demanding installation methodology.

Hong Kong North Lantau Expressway, Tai Ho Section MTRC traction substation 8.000 m3 of stone columns.

A Word on Environment

The stone column is possibly the most “natural” foundation system in existence. Stone columns consist entirely of gravel, a substance that is found naturally in the subsoil. No additives are mixed into the stone columns. They are therefore not only environmentally neutral but also more durable than any other foundation system that would involve the use of cement or steel.
 

Penetration
The vibroprobe penetrates to the required depth by vibration and jetting action of water.

Installation
Adding gravel through the washed out annular space alongside the Vibroprobe creates the stone column.

Completion
The surface is leveled and roller compacte