TUNNELLING UNDER COMPRESSED AIR - THE EXPERIENCE ON SITE AND A LABORATORY TEST

In shallow tunneling below groundwater table compressed air can be used for preventing water inflow into the tunnel during construction. During tunneling with a shotcrete support airloss takes place which has to be compensated permanently to maintain the required air pressure. The air leaks thereby through the unsupported tunnel face and the shrinkage cracks of the shotcrete support.