Geotechnical Parameters of Sydney Sandstone （岩土参数的悉尼砂岩）.pdf

SYDNEY SANDSTONE AND SHALE BERTUZZI PELLS GEOTECHNICAL PARAMETERS OF SYDNEY SANDSTONE AND SHALE Robert Bertuzzi Philip J.N. Pells Pells Sullivan Meynink Pty Ltd, Sydney 1 INTRODUCTION The classification system for Sydney sandstone and shales, through the Australian Geomechanics Society (Pells et al, 1978; Pells, Mostyn and Walker, 1998) was intended to assist in the design of foundations on rock in the Sydney area. The five class system has proved to be a good tool for communicating rock mass quality for other geotechnical projects such as tunnels and deep basement excavations. However, the classification system is not a design tool for works other than foundations on rock. Tunnels, slopes, deep basements and retaining walls should be designed using normal methods of applied mechanics. However, such methods, whether hand stability calculations or complex analyses using programs such as UDEC, require engineering parameters covering strength and deformation characteristics. In some instances, such as rock substance strength and modulus, the parameters may be measured by laboratory testing. However, when it comes to rock mass parameters use has to be made of parameters back figured from monitoring of actual excavations and retaining structures; published correlations from other geological environments, such as mass modulus versus RMR; or semi-theoretical approaches such as Hoek’s approach of estimating mass modulus from Hoek- Brown parameters. Unfortunately, when one scratches the surface many of these correlations and guidelines are based on scant data and they must be used with great caution. This paper summarises