ABSTRACT
This chapter discusses the blastings to open ramps, for ground levelling and foundations, and for swelling of rocks or preblastings. The rock excavations done by blasting in highway and railway construction are of two different types: through cut and side hill cut. Due to the importance of rock condition in the remaining walls, especially those of elevated height, it is normal to finish the excavation with contour blastings, which is another reason to keep the depth of cut from 10 to 12 m, in order to maintain drilling precision. The usual diameters vary between 65 and 125 mm. Trenches are the lineal surface operations with a width of between 0.8 and 3 m, and a depth that can oscillate between 0.5 and 5 m. The size of the blastings should be as large as possible to avoid excessive movement of the machinery, road traffic interuptions, and to do this, sequential blasting machines or milisecond delays are used.
