INVESTIGATION OF CAUTIOUS BLASTING MODEL APPLIED DURING TUNNELING OF USKUDAR-UMRANIYE-CEKMEKOY SUBWAY CONSTRUCTION

Abstract

Traffic and transportation have become daunting problems in almost every metropolitan area in the world today. Public transportation systems appear to be the sole genuine solution to these problems. One of the most convenient types of transportation in metropolitan areas is subway systems. In Istanbul, a number of new subway lines are under construction to solve the ever-increasing traffic problem of the city. The Uskudar-Umraniye-Cekmekoy line is one of the most important subway lines under construction on the Asian side of the city since traffic congestion in this area is impossible to be tackled with in any other way. Because there is no suitable location for shaft opening within the construction area of the Bulgurlu station (the sixth station), an approach tunnel has been built by the NATM starting from a point 200 meters away from the station. This paper examines the blasting operations carried out during the excavation of the approach tunnel, focusing upon the vibrations induced by blasting and the effects of blasting on the residential structures. The Peak Particle Velocity (PPV) and frequency were measured and evaluated according to the USA (USBM) norms. During the 50 controlled blasting operations conducted until now, the vibrations were recorded 94 times by means of various technical apparatuses. By relating the vibration records to the scaled distance calculated on the basis of the explosive weights per delay, the ground transmission coefficient (K) and the geological coefficient (beta) were found.