METHOD PREVENTING PENETRATION OF WATER INTO DEEPLY LAID TUNNELS DURING REPAIR AND RECONSTRUCTION OPERATIONS Russian patent published in 1998 - IPC

FIELD: construction industry. SUBSTANCE: method includes preliminary water tightening of repaired section by coffer-dams, formation of positive pressure in repair zone by supply of liquid cooling agent, for example liquid nitrogen, till soil behind tunnel lining is frozen to depth of 20 cm as minimum. After this gas pressure is reduced to atmospheric one and air cooled to negative temperature kept during whole period of operations is supplied. EFFECT: increased productivity and efficiency of method. 1 dwg