The Testing of bond stress parameters for rock anchors in southeast Queensland

Author: Mohsen Sadeghi

A significant percentage of TMR road assets is founded in the Neranleigh Fernvale and Brisbane Tuff Stratigraphic Units of Southeast Queensland.  A study of Proof Test data from testing of sacrificial ground anchors constructed within materials from the Brisbane Tuff and Neranleigh Fernvale Beds for an infrastructure project in Brisbane was carried out to consider bond stress values at the grout-ground interface.  Details of anchor construction and testing procedures are presented, together with the adopted approach to test interpretation. Data from Proof Testing of ground anchors bonded into these materials is then interpreted and evaluated for each unit, with relationships developed for each rock type for ultimate and yield bond stress values at the grout-ground interface as a function of rock substance strength (UCS) and rock mass strength (based on Hoek and Brown, 2018). For both rock types, grout-ground interface bond stresses increase with rock strength and quality, with better correlations evident based on rock mass strength than for UCS data. Comparisons of the interpreted bond stress relationships based on UCS are made for both rock types to published information for ground anchors and shaft adhesion parameters for cast-in-situ piles. Suggestions are made for amendments to the testing requirements of MRTS03 to improve assessment of bond stress.

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    October 2025

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    13 October 2025

  • Abstract submissions close

    31 January 2026

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    April 2026

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    May 2026

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    May 2026

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    18-20 August 2026

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