材料期刊网

冲击凿入效率(施于岩石破碎的能量对冲击能量之比)是评价和设计冲击凿入系统的重要参量.本文运用一维应力波理论导出了任意入射应力波形的凿入函数;对任一给定的单圆柱和双圆柱活塞-长杆硬岩凿入系统,其各阶凿深系数(u~*k)可示为波形向量(ψ_k)的线性变换;由矩阵或递推公式表达为: (u~*_k)=(α_(kp))(ψ_k)或 u~*_k=u~*_k-1~(e-λ+ψ_k)则凿入效率: η=4θ(1-e~(-λ))~2(maxu~*_k)~2式中 (α_(kp))——系统特性方阵; (λ,θ)——系统常数. 用电子计算机计算了活塞柄头长度比j=(4,5)(工程常用值)两种情况下具有不同断面特性的双圆柱活塞的凿入效率(单圆柱活塞可视为双圆柱活塞的特例). 对任意确定的入射应力波形,都可用足够小周期△t的阶梯函数来逼近,所以这个方法可以推广到任意入射应力波形凿入效率的计算.

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.