Abstract
Force-displacement curves such as penetration resistance-penetration curve in rock drilling have very important role for accurately estimating the performance of excavation machinery. The simplest model to represent the bit-rock interaction is a linear spring of which the spring constant is used to be determined experimentally and so difficult to find the relation with the rock physical properties. In this study, a variable compliance type constitutive equation proposed on the basis of experimental data was used instead of the conventional linear spring.
Simulation to estimate penetration-time and penetration resistance-time curves were carried out for four excavation machines; rock drill, large rock hammer, roadheader and tunnel boring machine. In all cases, penetration resistance increases linearly at first and soon reaches the peak value that depends on parameters in the constitutive equation. Finally the resistance decreases very rapidly. The calculated results are considered to be reasonable and consistent with the measured data in qualitative means. It can be said that the proposed method could be applied to more realistic and sophisticated simulations combined with FEM or other appropriate calculation methods.
