High-fidelity modelling of impact breakage in percussive drilling
File(s)
Author(s)
Yang, Xiaowei
Type
Thesis
Abstract
The accurate simulation of complex rock failure behaviour in excavation and comminution (e.g., rock crushing and pulverisation) has long been a challenge, particularly in light of the growing demand for subsurface resources and energy. High-fidelity modelling is essential in this field as it enables a deeper understanding of rock failure mechanisms, facilitating the optimisation of drilling operational parameters and tool design. In this research, the combined finite discrete element approach was applied for the first time to rotary percussive drilling simulations, providing a high-fidelity numerical modelling framework in this domain. The integration of a strain-rate effect model and a friction-related pulverisation model enabled the simulation of distinct failure modes in various hard rocks under dynamic point loading. A robust multi-criteria validation approach was proposed and implemented for three types of hard rocks subjected to impacts from hemispherical and ballistic inserts to validate the single-impact model. Compared to conventional single-criterion validation methods based on quasi-static experiments or impact tests, the multi-criteria validation approach demonstrated the high fidelity of the simulations by verifying several key aspects, including bit motion, fragment mass, crater morphology, radial crack length, the sequence of failure modes, and internal crack patterns. Leveraging this high-fidelity model, the energy evolution and dissipation processes during impact-induced rock failure were analysed for the first time, providing new insights for optimising energy utilisation. Additionally, the role of shearing introduced by bit rotation during bit-rock interaction was investigated, uncovering its contribution to the fragmentation process. Building on the validated single-impact model, a multi-impact model was developed to represent the percussion action of a multi-insert bit to study the influence of drilling operational parameters on the drilling rate. This model serves as a valuable tool for optimising operational parameters based on the mechanical properties of different rock types.
Version
Open Access
Date Issued
2025-05-10
Date Awarded
01/07/2025
Advisor
Latham, John-Paul
Xiang, Jiansheng
Publisher Department
Department of Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)