Overview

Hydrothermal veins are often overlooked or misinterpreted within deep, heterogeneous rock masses, yet their behaviour can dramatically influence tunnelling outcomes. In his award winning 2025 David Sugden Award paper, Yosafat Sinaga reveals how these vein systems are frequently mistaken for open joints, leading to inaccurate geological models and flawed design assumptions. This session will explore why correct vein characterisation is essential for both safety and project efficiency. Misjudging these features can result in two costly extremes: overly conservative support designs that inflate construction budgets, or unexpected, hazardous rockbursts triggered by misunderstood ground conditions. By examining real case insights and engineering implications, this event will provide tunnelling and geotechnical professionals with a deeper understanding of the subsurface complexities that lie beneath, and how better interpretation can reduce risk and improve decision making.

Program timeline

5:30pm AEST – Registration and networking

6:00pm AEST – Presentation commences

6:50pm AEST – Q&A

7:00pm AEST – Presentation concludes, networking

7:30pm AEST – Event concludes

Learning outcomes

1. Walk away with practical steps to avoid design errors caused by misinterpreting veins in deep tunnel projects.
2. Correctly interpret veined rock masses in core logging and face mapping and recognise when “broken-looking” core does not mean a poor-quality, jointed rock mass.
3. How vein intensity and in situ stress interact to drive overbreak, damage propagation, and reinforcement demand in high-stress excavations

About the speaker

Yosafat Sinaga

Geotechnical Engineer, NOMA Consulting

Yosafat Sinaga is a Geotechnical Engineer at NOMA Consulting with over five years of experience delivering geotechnical design and construction support for mining and tunnelling projects in Australia, Singapore, Papua New Guinea, and Indonesia. He has contributed to major infrastructure and underground mining developments, specialising in rock mass and structural geological characterisation, advanced 2D and 3D numerical modelling, and primary tunnel support design optimisation. His recent project work includes optimising primary support design for road tunnels excavated using the Drill & Blast method, developing detailed designs for temporary Earth Retaining and Stabilising Structures (ERSS) for rail and service tunnels, and providing geotechnical input for underground copper mining projects employing sub-level and block caving methods.