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A STUDY OF THE EFFICIENCY OF PERCUSSIVE PENETRATION BY WAVE THEORY |
Zhao Tongwu Changsha Institute of Mining and Metallurgy Research |
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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.
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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.
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Received: 18 March 1980
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[1] Simon, R., Int. J. Rock Mech. Mining Sci., 1 (1964) , 397. [2] Hustrulid, W. A. and Fairhurst, C., Int. J. Rock Mech. Mining Sci., 8 (1971) , 311, 9 (1972) , 417. [3] Lundberg, B., Int. J. Rock Mech. Mining Sci., 10 (1973) , 401. [4] 徐小荷,金属学报,6(1963) ,1. [5] Fischer, H. C., Appl. Sci. Res., A8 (1959) , 105, 278. [6] Arndt, F. K., Glueckauf, 96 (1960) , 1516. [7] Fairhurst, C., Mine Quarry Eng., 27 (1961) , №3, 122; №4, 169. |
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