The research is supported by the National Natural Science F ounda-tion of China( No.49972 0 5 7) and the China Geological Surv
Flood disaster has been a serious hidden danger since the ancient time. The essential cause for the fact that floods have not been eliminated for hundreds of years is that time honored strategies do not suit the case...
Recently impregnated diamond bits have been widely applied in drilling hard and medium - hard formations in the world . It is quite necessary to study the fracturing mecha-nism of the impregnated diamond bit and the c...