On 7 September 2026, the Hong Kong Tunnelling Society (HKTS) and the HKIE Geotechnical Division recently hosted a highly engaging seminar entitled “How Wide Can a Rock-Reinforced Cavern Be Opened?”, presented by Ir. Keith W.K. Kong, attracting over 350 participants both physically and online. The event explored one of the most fundamental questions in underground engineering: the practical limits of cavern span supported by rock reinforcement systems.
Drawing upon both natural and engineered large-span caverns, Keith presented an extensive research involving a comprehensive parametric study supported by advanced Finite Element Analysis (FEA). The modelling work was rigorously verified against alternative numerical approaches, including finite difference, providing confidence in the robustness of the findings.
The presentation highlighted the critical influence of rock mass quality, in-situ stress conditions and cavern geometry, particularly arch shape, on achievable span widths. The attendees gained valuable insights from Keith’s profound understanding of cavern design and rock engineering, making for a thought-provoking and well-received evening.
