BLASTING IN TUNNEL DRIVING

SPRENGERSCHUETTERUNGEN BEIM TUNNELVORTRIEB

THE CONSTRUCTION OF FAIRLY LONG TUNNELS FOR MOTORWAYS AND FAST ROADS IS COMPLETED IN TWO STAGES; THE SECOND TUNNEL TUBE IS NOT STARTED UNTIL SOME YEARS AFTER THE COMPLETION OF THE FIRST, WHEN TRAFFIC IS ALREADY USING THE FIRST TUBE. DURING CONSTRUCTION OF THE SECOND TUBE BLASTING HAS TO BE KEPT TO A MINIMUM TO AVOID DAMAGE TO THE FIRST TUBE. THE MAGNITUDE OF THE STRESS ON THE EXISTING TUBE CAUSED BY THE BLASTING IS DETERMINED BY THE DISTANCE FROM THE POINT OF BLASTING, THE GEOLOGY OF THE ROCK, THE TYPE OF BLASTING PROCEDURE ADOPTED, SIZE OF THE EXCAVATION CROSS SECTION, DEPTH OF COVER ETC. THE AIM OF THE PROJECT IS TO DETERMINE THE RELATION BETWEEN STRESS CAUSED BY BLASTING AND THE ABOVE-MENTIONED FACTORS AND TO DEFINE PERMISSIBLE LIMIT VALUES OF BLASTING.