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X-WR-CALDESC:Events for Australian Tunnelling Society
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DTSTART:20250101T000000
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DTSTART;TZID=Australia/Brisbane:20260604T180000
DTEND;TZID=Australia/Brisbane:20260604T190000
DTSTAMP:20260505T005210Z
CREATED:20260505T005210Z
LAST-MODIFIED:20260505T005210Z
UID:291886-1780596000-1780599600@australiantunnellingsociety.com.au
SUMMARY:The ground investigation for a storage cavern in metamorphic rock at 600 m depth
DESCRIPTION:Overview\nThis presentation describes the processes used in the investigations for a deep compressed air storage cavern in a complex metamorphic environment. The exploration process involved drilling using HQ-3 coring techniques from surface and also from an adjacent underground mine. The latter were two 460 m boreholes drilled just sub horizontally across the planned cavern location. \nThe core from these holes was logged for structure and sampled for rock property testing. Because a significant portion of the rock was highly anisotropic the test methods used had to be adapted. This included alternative ways of working with point load testing\, triaxial testing for anisotropy of moduli and some special shear tests.  Because of the importance of determining potential leakage of groundwater into the cavern\, or of air out of the cavern\, the correct measurement of the ground fluid pressure and the permeability of the rock mass were extremely important. \nTesting had to be conducted in stages to cover the entire length of the holes. The method used was to fit the drill rods with a straddle packer assembly\, downhole valve system and suitable precision pressure monitoring with operator read out. First the test zone was shut in to recover pressure. This was followed by a period of injection or production which was followed by another shut in period. These tests followed oilfield practice but with tools designed to work with HRQ drill rod and used horizontally. \nThe rock stress was determined by the use of three dimensional overcore tools used up to 441 m laterally. Other techniques could have also been advantageously used to fill in the sparse overcore data in the extremely complex geological environment. The vertical and the horizontal holes were logged using both acoustic televiewer and full wave sonic sondes. \nThe conclusions of the study were that the rock mass was heterogeneous but fit for purpose provided that the correct design decisions were made. The presentation also looks at what can be achieved from open hole drilling test techniques compared to coring and the comparative costs of these. This has particular relevance to tunnel investigations. \nProgram timeline\nOnline \n6.00pm – Presentation commences \n7.00pm – Presentation concludes \nIn-Person \n5.30pm – Registration\, networking & catering \n6.00pm – Presentation commences\, networking \n7.00pm – Event concludes \nLearning outcomes\n\nYou should gain an appreciation of the importance of geology.\nYou will gain an understanding of the methods used to determine the states of stress in rock and the measurement of anisotropic rock properties.\nThe methods used and the importance of determining fluid pressures and permeability properly are extremely important and should totally replace conventional packer testing.\n\nAbout the speaker\n\n\n\nIan Gray\nManaging Director\, Sigra Pty Ltd\n\nDr Ian Gray is the managing director of Sigra Pty Ltd\, a role he has held for 32 years. In his career he has had the roles of mining\, civil\, geotechnical and reservoir engineers\, engineering geologist and hydrogeologist. He has worked in 20 countries dealing with mines\, tunnels\, slopes\, petroleum reservoirs and anything else in the ground. One of his passions is actually measuring things in the ground properly. To do this he has developed a suite of equipment and techniques. He also works with a variety of drilling systems.
URL:https://australiantunnellingsociety.com.au/ats-event/the-ground-investigation-for-a-storage-cavern-in-metamorphic-rock-at-600-m-depth/
LOCATION:Online and in person at: Level 9\, 340 Adelaide Street\, Brisbane
CATEGORIES:Online,Queensland,Webinar
ATTACH;FMTTYPE=image/png:https://australiantunnellingsociety.com.au/wp-content/uploads/2026/05/Screenshot-2026-05-05-105122.png
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DTSTART;TZID=Australia/Brisbane:20260625T173000
DTEND;TZID=Australia/Brisbane:20260625T193000
DTSTAMP:20260430T060853Z
CREATED:20260309T032436Z
LAST-MODIFIED:20260430T060853Z
UID:256542-1782408600-1782415800@australiantunnellingsociety.com.au
SUMMARY:David Sugden Roadshow - Brisbane - Uncovering veins: impacts on deep tunnel engineering
DESCRIPTION:Overview\nHydrothermal 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. \nProgram timeline\n5:30pm AEST – Registration and networking \n6:00pm AEST – Presentation commences \n6:50pm AEST – Q&A \n7:00pm AEST – Presentation concludes\, networking \n7:30pm AEST – Event concludes \nLearning outcomes\n\nWalk away with practical steps to avoid design errors caused by misinterpreting veins in deep tunnel projects.\nCorrectly 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.\nHow vein intensity and in situ stress interact to drive overbreak\, damage propagation\, and reinforcement demand in high-stress excavations\n\nAbout the speaker\n\n\n\nYosafat Sinaga\nGeotechnical Engineer\, NOMA Consulting\nYosafat 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.
URL:https://australiantunnellingsociety.com.au/ats-event/uncovering-veins-impacts-on-deep-tunnel-engineering/
LOCATION:Engineers Australia QLD\, Level 9\, 340 Adelaide St\, Brisbane\, QLD\, 4000\, Australia
CATEGORIES:Queensland
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