Within a well-established stress environment and with well-established laboratory properties, Hawkesbury Sandstone in the Sydney region of Australia hosts, and will continue to do-so, a significant proportion of the underground infrastructure. In order to conduct the most rigorous geotechnical design, it is recognized that the impact of scale on the response of the excavated system must be well understood. In this regard, one of the major challenges is to translate the small measured (laboratory) geomechanical properties and those of the joints observed at a larger scale to a scale and stress-dependant strength value for design. This study provides a comprehensive review of existing geomechanical data for the Hawkesbury Sandstone and provides an analysis of strength-scale dependency. Large-scale, Synthetic Rock Mass (SRM) tests have been completed to establish a strength-scale relationship that consider defect spacing. Validation of the SRM sample responses has been completed for both the strength and deformation modulus based on reported and/or commonly accepted characteristics of a tunnel-scale rock mass. The post-peak, strain-softening behaviour of SRM samples has been used to establish the critical plastic shear strain and residual strength of each class of Hawkesbury Standstone at the excavation scale. A correlation between the Geological Strength Index (GSI) and the peak and residual strength has been derived.

在良好的压力环境和良好的实验室性能中，澳大利亚悉尼地区的霍克斯伯里砂岩拥有并将继续这样做，在地下基础设施中占很大比例。为了进行最严格的岩土工程设计，必须认识到规模对开挖系统响应的影响。在这方面，主要挑战之一是将较小的测量（实验室）地质力学特性和在较大规模上观察到的接缝的力学特性转换为设计所需的比例和应力相关强度值。这项研究对霍克斯伯里砂岩的现有地质力学数据进行了全面回顾，并对强度尺度依赖性进行了分析。大规模，已完成合成岩体（SRM）测试，以建立考虑缺陷间距的强度-比例关系。基于已报告和/或公认的隧道规模岩体特征，已经针对强度和变形模量完成了SRM样品响应的验证。SRM样品在峰后的应变软化行为已用于确定开挖规模下各类Hawkesbury Standstone的临界塑性剪切应变和残余强度。得出了地质强度指数（GSI）与峰值强度和残余强度之间的相关性。基于已报告和/或公认的隧道规模岩体特征，已经针对强度和变形模量完成了SRM样品响应的验证。SRM样品在峰后的应变软化行为已用于确定开挖规模下各类Hawkesbury Standstone的临界塑性剪切应变和残余强度。得出了地质强度指数（GSI）与峰值强度和残余强度之间的相关性。基于已报告和/或公认的隧道规模岩体特征，已经针对强度和变形模量完成了SRM样品响应的验证。SRM样品在峰后的应变软化行为已用于确定开挖规模下各类Hawkesbury Standstone的临界塑性剪切应变和残余强度。得出了地质强度指数（GSI）与峰值强度和残余强度之间的相关性。