Wire cutting as a complement to drill and blast in vibration sensitive environments

In vibration sensitive environments traditional excavation methods such as the Austrian method (drill and blast) or tunnelling with a TBM (tunnel boring machine) may not be suitable. The aim of this thesis is to investigate what differences might be if excavation is done with wire cutting instead. The differences will be viewed from following perspectives: geometry and stress situation, economy and time, and effects on the surroundings with focus on vibrations. The different tunnel profiles and the resulting stress properties have been examined in computer simulations to visualize the differences. Because of the limitation in tunnel profiles a wire cut profile will have a more rectangular shape which may have unfavourable stress properties. It will result in stress concentrations and tensile stresses which implies for more reinforcements to secure the loose rock mass. To see the economic differences of the methods two blasted tunnels with different vibration regulations have been examined and compared with wire cutting. Data from two blasted tunnels with different vibration regulations have been used to calculate a price for one excavated cubic meter of rock. The comparison shows that wire cutting is roughly twice as expensive as drill and blast for the tunnel with high vibration regulations. The difference is greater for the tunnel with less vibration regulations. The practical aspects of the different techniques are hard to estimate in monetary values. Because of its higher price wire cutting has only been used for special applications or when vibration regulations make blasting impossible. Wire cutting can be performed close to very vibration sensitive constructions or in the vicinity of people but to a higher cost than conventional drill and blast method.