Injection system for underground preparation has a high pressure water cutting jet with a surrounding air stream and with an additional air jet under the cutting jet to extend the cutting range

摘要

An injection system for underground preparation to install barrier layers, e.g. for water proofing foundations etc., has a vertical shaft (9) with separate feeds for high pressure water (5) and compressed air (4). The water feeds a cutting jet (3) with the cutting action enhanced by air jets (2) around the cutting jet. The invention further enhances the cutting action by fitting an additional air jet (6) under the cutting jet, with its air stream angled slightly upwards to cross the cutting jet at a set distance from the shaft. The additional jet clears debris and suspension and extends the reach of the cutting jet without undue increase in energy.