Control Blasting Technique for Rock Cutting Expansion of Existing Expressway

摘要

It is usually impossible to hold up the traffic a long time for a full closed construction during the expressway rebuilding and expanding.Not only the seismic wave and air shock wave,but also the throwing and rolling rocks are the key factors to a unblocked expressway.The control rock cutting expansion blasting technique is researched with the expanding project of G4 Expressway.Firstly,the approach of shallow-hole blasting and thin layer peeling is adopted to control the amplitude of seismic wave and air shock wave by means of strictly control the explosive charge and ensure the stemming length.Then change the direction of minimal resistance line,set up multiple protecting walls and guard nettings by use of the vegetation on the upper side slope and reserved rock wall on the original side slope or revetment to reduce the volume and quantity of throwing and rolling rocks.Followed by the pre-splitting blasting and multi row millisecond extruding blasting to ensure good smoothness and stability of the side slope and the boulder yield is within 10％.Engineering results show,the proposed methods are economical and practical,vibration,shock wave and the throwing rock have been effectively controlled as well as the quality and construction progress of the rock fill roadbed and has a guiding significance for the construction of similar projects.