ENGINEERING GEOLOGICAL ASSESSMENT AND GROUND BEHAVIOR OF TECTONICALLY DISTURBED ROCKS IN NORTHERN THAILAND. A CASE STUDY OF THE PHAYAO RAILWAY TUNNELS

AUTOR(I) / AUTHOR(S): Supawit Prarom, Pornkasem Jongpradist, Thanet Thongdetsri, Noppadol Phien-wej, Daniel Dias, Sirisin Janrungautai, Damrong Amorndechaphon, Anat Hasap

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DOI:  10.46793/ACUUS2025.2.14.68

SAŽETAK / ABSTRACT:

This paper presents a geotechnical analysis of the southern Phayao Tunnels (T3), which are part of the Denchai-Chiang Rai-Chiang Khong Railway Construction Project (Contract 2, Ngao-Chiang Rai section) in the Lampang-Phrae Basin, Thailand. The geological and geotechnical challenges during tunnel construction are highlighted, focusing on analyzing rock mass behavior and events during tunnel excavation. The research has integrated data from three sources, including borehole investigation data, seismic refraction survey data, and actual field observations, to provide a comprehensive overview of the project area’s geological conditions for assessing the rock mass’s geotechnical properties. In evaluating rock mass properties, the study applied the Rock Mass Rating (RMR) system and Geological Strength Index (GSI), which helped efficiently classify and predict rock mass behavior in the tunnel area. Additionally, the study monitored and analyzed tunnel movements (convergence monitoring) to assess structural stability. Incidents that occurred during construction were analyzed in detail to identify the main causes and contributing factors and present effective and appropriate problem-solving approaches during tunnel excavation operations. The results of this study not only enhance understanding of tunnel construction in complex geological structures but also present recommendations for developing practical guidelines for future tunnel construction projects, especially in the context of challenging geological conditions in Thailand. The knowledge gained from this study can be applied to planning and risk management for large infrastructure projects facing similar geotechnical challenges.

KLJUČNE REČI / KEYWORDS:

Tectonically Disturbed Rocks, Complex Geological Structures, Engineering Geological Assessment, Ground Behavior

PROJEKAT / ACKNOWLEDGEMENT:

This research has received funding support from the NSRF via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation [grant number B13F670082-11]

The compilation of this research data would like to thank the officials and personnel of the State Railway of Thailand, the CSDCC Consulting Group, the CH. Karnchang-Sino-Thai Engineering & Construction Public Company Limited, CKST Joint Venture, the Den Chai-Chiang Rai-Chiang Khong Railway Construction Project, Contract 2, Ngao-Chiang Rai Section, and Right Tunneling Public Company Limited for supporting the data and facilitating the research to achieve the objectives.

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