Procedure for the construction of cross passages in double pipe tunnels

A method for the construction of underground transport infrastructures, comprising the steps of:

• excavating at least an underground transport tunnel comprising a first pipe and a second pipe substantially parallel to one another;
• and
• making at least a bypass tunnel connecting said first pipe and said second pipe;
• wherein said making at least a bypass tunnel comprises the sub-steps of:
• introducing a launching chamber along said first pipe up to a first predefined position chosen along a longitudinal direction of said first pipe, said launching chamber configured to launch at least a tunnel boring machine;
• introducing an arrival chamber along said second pipe up to a second predefined position chosen along a longitudinal direction of said second pipe, said arrival chamber configured to receive said tunnel boring machine as launched by said launching chamber;
• and
• excavating said bypass tunnel making said tunnel boring machine move forward from said launching chamber to said arrival chamber along a direction transverse to said longitudinal direction of each of said first pipe and said second pipe;
• wherein said excavating the bypass tunnel comprises:
• pushing said tunnel boring machine along said transversal direction by means of a thrust system present in said launching chamber;
• conveying a plurality of precast segments along said first pipe up to said launching chamber;
• interposing said precast segments one by one between said tunnel boring machine and said thrust system as said boring machine moves forward along said transversal direction;
• and
• pumping a carrier fluid on material to be excavated by said tunnel boring machine and discharging the excavated material mixed with the carrier fluid;
• wherein, before starting said excavating the bypass tunnel by the tunnel boring machine, the method comprises impermeabilizing said launching chamber to said first pipe, including construction of a first impermeabilization structure having a first shaped wall substantially corresponding to a portion of the first pipe and configured to prevent the carrier fluid from flooding the first pipe, and impermeabilizing said arrival chamber to said second pipe, including construction of a second impermeabilization structure having a second shaped wall substantially corresponding to a portion of the second pipe and configured to prevent the carrier fluid from flooding the second pipe.