TUNNEL HARDENING THROUGH INNOVATIVE ROCK BOLTS AND SHOTCRETE LINERS

DEEP BASING FACILITIES REQUIRE THAT STRUCTURES BE PROTECTED AGAINST BLAST EFFECTS. INHERENT IN THIS NEED IS FOR THE TUNNEL SUPPORT SYSTEM TO BE ECONOMICALLY INSTALLED AND CAPABLE OF WITHSTANDING OVERSTRESSES WHICH MAY REACH OR EXCEED 1 KILOBAR. IN ORDER TO MORE EFFICIENTLY HARDEN A STRUCTURE, THE SUPPORT SYSTEM SHOULD BE MADE MORE DUCTILE SO THAT IT CAN UNDERGO DEFORMATION WHILE RETAINING ITS ABILITY TO RESIST LOADING. ONCE CONCEPT FOR DEVELOPING THIS DUCTILITY IS THE USE OF INNOVATIVE ROCK BOLTS AND SHOTCRETE LINERS. PATTERENED ROCK BOLTS AND SHOTCRETE ARE GENERALLY MORE ECONOMICAL THAN MONOLITHIC CONRETE WITH FRANGIBLE BACKPACKING, HOWEVER, TESTING HAS LIMITED THEIR EFFECTIVENESS TO THE 1/4 KBAR RANGE. THEREFORE, THE NEED EXISTS TO DEVELOP A ROCK BOLT - SHOTCRETE LINING SYSTEM WHICH PROVIDES GREATER LEVELS OF HARDNESS BUT REMAINS MORE ECONOMICAL THAN THE CAST-IN-PLACE CONCRETE LINERS. THIS ANALYSIS WILL DEVELOP THIS SYSTEM.