The problem of poor blasting effect and low efficiency is widespread in the excavation of large outwash accumulation, which has complex composition of particulate matter,different cementation characteristics and uneven spatial distribution.With the excavation of Xiazanri outwash accumulation in Liyuan hydropower station,the drill blasting excavation parameters and construction technology were researched based on the blasting crater theory analysis,indoor experiment,and field test.The results showed that the outwash accumulation could be classified into three levels of strong cementation,compact weak cementation,and weak cementation,based on its physical mechanical property and construction characteristic.The optimal resistance should be 2.5~3.5 m, the hole depth should be 2~3 m and the explosive consumption should be 0.3~0.35 kg/m3for strong cemented outwash accumulation. The optimal resistance should be 3m or 4 m,the hole depth should be 3~4 m and the explosive consumption should be 0.28~0.3 kg/m3for weakly cemented outwash accumulation.The blasting technology of using high air pressure drilling rig,φ70 cartridge,plane area multipoint blasting and shallow stair of 3~4 m was raised.The results applied well in the excavation of Xiazanri outwash accumulation and it could be used as a reference for the excavation construction of large outwash accumulation in the southwest.
