Investigation of a hydraulic impact: a technology in rock breaking

TL;DR

This study uses finite element analysis and dimensional analysis to investigate how various parameters affect the effectiveness of hydraulic impact in non-explosive rock breaking, aiming to optimize the technology.

Contribution

It provides a detailed parametric analysis of hydraulic impact, identifying key factors influencing rock stress and offering guidance for optimizing non-explosive rock breaking methods.

Findings

Increasing piston velocity significantly raises rock stress.

Material density has negligible effect on stress.

Optimizing piston velocity enhances rock breaking efficiency.

Abstract

The finite element method and dimensional analysis have been applied in the present paper to study a hydraulic impact, which is utilized in a non-explosive rock breaking technology in mining industry. The impact process of a high speed piston on liquid water, previously introduced in a borehole drilled in rock, is numerically simulated. The research is focused on the influences of all the parameters involved in the technology on the largest principal stress in the rock, which is considered as one of the key factors to break the rock. Our detailed parametric investigation reveals that the variation of the isotropic rock material properties, especially its density, has no significant influence on the largest principal stress. The influences of the depth of the hole and the depth of the water column are also very small. On the other hand, increasing the initial kinetic energy of the piston can dramatically increase the largest principal stress and the best way to increase the initial kinetic energy of the piston is to increase its initial velocity. Results from the current dimensional analysis can be applied to optimize this non-explosive rock breaking technology.