A STUDY OF THE EFFICIENCY OF PERCUSSIVE PENETRATION BY WAVE THEORY
Zhao Tongwu Changsha Institute of Mining and Metallurgy Research
Cite this article:
Zhao Tongwu Changsha Institute of Mining and Metallurgy Research. A STUDY OF THE EFFICIENCY OF PERCUSSIVE PENETRATION BY WAVE THEORY. Acta Metall Sin, 1980, 16(3): 263-275.
Abstract Using uni-dimentional stress wave theory, the penetration function of arbitra-rily incident stress has been derived. For any given long rod-hard rock penetrationsystem with single or double cylindrical piston, the coefficient of the penetrationdepth of each step (u_k) is a linear transform of a pulse-shape vector (ψ_k), andcan be expressed by means of matric or recurrent formula as: (u_k)=(α_(kp))(ψ_k) oru_k=u~(k-1)e~(-λ)+ψ_k, therefore, the penetration efficiency isη=4θ(1-e~(-λ))~2 (max u_k)~2where (α_(kp)) is the characteristic square matrix of system: λ and θ are constants. Attempts have been made to compute the penetrating efficiency of the doublecylindrical piston with different cross-section characteristics by a digital computer,with the shake to head length ratio j=4 or 5, which is the normal value forengineering design. The single cylindrical piston may be regarded as a particularcase of the double one. Owing to the fact that all arbitrary specific incident stress pulse can be ap-proached by a step function with a sufficiently short period Δt, this method maybe applicable to the calculation of the efficiency of penetration with arbitrarystress pulse.
