Australian Geomechanics Journal and News of the Australian Geomechanics Society Volume 42 No 1 March 2007 Landslide Risk Management ISSN 0818-9110 3 ISSN 0818-9110 AUSTRALIAN GEOMECHANICS JOURNAL AND NEWS OF THE AUSTRALIAN GEOMECHANICS SOCIETY Volume 42 Number 1 March 2007 PUBLISHED BY THE AUSTRALIAN GEOMECHANICS SOCIETY, NATIONAL SECRETARIAT, P.O. BOX 955, ST IVES, NSW 2075 The AUSTRALIAN GEOMECHANICS SOCIETY is jointly sponsored by: Engineers, Australia and The Australasian Institute of Mining and Metallurgy Responsibility for the content of this publication rests upon the authors and not on Engineers Australia nor the Australian Geomechanics Society. Data presented and conclusions developed by the authors are for information only and are not intended for use without independent substantiating investigation on the part of the potential user. 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The Society encourages reproduction of its publications and consent is usually looked upon favourably. It is a requirement that full and complete acknowledgement be cited when referencing articles published in Australian Geomechanics. Front Cover: Cliff-top residential developments at North Bondi The coastal cliff line that approximates the eastern boundary of the residential properties shown is 22 metres high. The cliff is composed of massive facies and sheet facies strata of Hawkesbury Sandstone that are characterised by sub-horizontal bedding planes, inclined cross-beds and sub-vertical intersecting joint sets. As less resistant strata are weathered and eroded by exposure to the elements, overlying strata are undercut. As undercutting advances, the overlying strata eventually collapse due to brittle failures occurring along the abovementioned rockmass defects. This is the dominant process in the natural cliff line regression that occurs in Hawkesbury Sandstone. The process is evidenced by the rock debris that litters the tidal rock platforms and it is also evidenced by the open rock fractures and the extent of the undercutting that can be seen in the cliff face. The above described natural regression processes have encroached across the eastern boundary of the properties in the cover photograph by over 4 metres. Photo and description courtesy of Greg Kotze. ii Australian Geomechanics Vol 42 No 1 March 2007 AUSTRALIAN GEOMECHANICS Volume 42 No 1 Contents March 2007 Chairman’s Column…………………………………………………………………..……………………………….....v AGS National Committee……………...…………………………………………………..……………..……………..ix LANDSLIDE RISK ASSESSMENT AND MANAGEMENT A National Landslide Risk Management Framework for Australia………………………………………………….1 Andrew Leventhal Guideline for Landslide Susceptibility, Hazard and Risk Zoning for Land Use Management…………...……….13 AGS Landslide Taskforce Landslide Zoning Working Group Commentary on Guideline for Landslide Susceptibility, Hazard and Risk Zoning for Land Use Management...37 AGS Landslide Taskforce Landslide Zoning Working Group Practice Note Guidelines for Landslide Risk Management…………………………………………………..………63 AGS Landslide Taskforce Landslide Practice Note Working Group Commentary on Practice Note Guidelines for Landslide Risk Management………………………………...……115 AGS Landslide Taskforce Landslide Practice Note Working Group Australian GeoGuides for Slope Management and Maintenance…………………………………………………..159 AGS Landslide Taskforce Landslide Slope Management and Maintenance Working Group Assessment of Landslide Likelihood in the Pittwater Local Government Area………………………………..…183 Patrick MacGregor, Bruce Walker, Robin Fell and Andrew Leventhal Rainfall Data Analysis and Relation to the Incidence of Landsliding at Newport……………………….….…….197 Bruce Walker An Assessment of Rockfall Frequency for the Coastal Cliff Lines of Pittwater Local Government Area, Sydney…………………..……………………………………………………………………………………213 Greg Kotze Book Reviews………………………………………………………………………………………………………….220 People………………………………………………………………………………………………..…………….…..222 Standards Australia…………………………………………………………………………………………………..224 Geodiary……………………………………………………………………………………………………………….225 EDITORIAL POLICY AND ADVERTISING RATES……………………………………..………………..........226 MEMBERSHIP APPLICATION FORM [All papers have been refereed in accordance with the full DETYA review process, unless stated otherwise.] Australian Geomechanics Vol 42 No 1 March 2007 iii AUSTRALIAN GEOMECHANICS SOCIETY National Committee Title Name, Initials Address for Correspondence Business Phone/Fax/email Mr M.A. (Marc) WOODWARD 31 Castle Street, Tel 08 9347 0000 Chair NORTH BEACH WA 6020 Fax 08 9347 0099 Mob 0417 911 131 [email protected] Mr N D (Neil) BENSON Golder Associates Pty Ltd Tel 03 8862 3500 Deputy Chair, Treasurer Level 3 50 Burwood Road Fax 03 8863 3501 HAWTHORN VIC 3122 Mob 0414 970 681 [email protected] Dr M B (Mark) JAKSA Dept of Civil & Env. Eng Tel 08 8303 4317 Immediate Past Chair UNIVERSITY OF ADELAIDE SA Fax 08 8303 4359 5005 [email protected] Prof J.P. (John) CARTER Faculty of Engineering and Built Tel 02 4921 6025 Vice-President ISSMGE Environment Fax 024921 7062 University of Newcastle Mob 0438 602 300 CALLAGHAN NSW 2308 [email protected] Dr A G (Tony) MEYERS PO Box 210 Tel 08 8302 3248 Vice-President ISRM Rundle Mall Fax 08 8302 3379 AUSIMM Representative ADELAIDE SA 5001 Mobile 0412 903 222 [email protected] Mr A (Alan) MOON Coffey Geotechnics Pty Ltd Tel 08 8352 1744 Vice-President IAEG 14B Henley Beach Road Fax 08 8234 0932 MILE END SA 5031 Mobile 0408 855 212 [email protected] Mr J P (Patrick) MacGREGOR PO Box 7183 Tel 02 4359 1023 Editor Australian Geomechanics MANNERING PARK NSW 2259 Fax 02 4359 3523 Mobile 0407 114 153 [email protected] Mr P J (Peter) GODFREY Coffey Geotechnics Pty Ltd P O Box Tel 03 9431 1300 IEAust Nominee 40 KEW VIC 3101 Mob. 0418 345 966 [email protected] Mr Graham SCHOLEY Golder Associates Tel 02 9478 3914 NSW Elected Member 88 Chandos St Mobile 0417 460 667 ST LEONARDS NSW 2065 [email protected] Mr Mark DRECHSLER PPK House Tel 08 8405 4300 SA & NT Elected Member 101 Pirie St Mobile 0419 929 354 ADELAIDE SA 5000 [email protected] Mr R M F (Fraser) WHITE 7 Mellifont Street Tel 03 6230 5315 Tas Elected Member WEST HOBART TAS 7000 Fax 03 6230 5266 Mobile 0429 708 934 [email protected] Mr Chris BOYD 1 Hampton Court Tel: 03 9653 8344 Victoria Elected Member IVANHOE VIC 3079 Home: 03 9499 5902 Mob: 0418 340 284 [email protected] Prof B (Barry) LEHANE School of Civil & Resource Tel 08 6488 2417 WA Elected Member Engineering Mob 0417 193 591 35 Stirling Highway [email protected] Crawley WA 6009 Prof D (David) Williams Department of Civil Engineering Tel 07 3365 3642 QLD Elected Member University of Queensland Mob 07 3721 5401 ST LUCIA Qld 4072 [email protected] Mr Stephen FITYUS 40 Russell Rd Tel 02 4921 5294 Newcastle Elected Member NEW LAMBTON NSW 2305 Mob: [email protected] Dr B.G. (Burt) Look, MIEAust CPEng 7 Ngeringa Crescent Tel 07 3246 4316 Chair – 10th ANZ Conference on CHAPEL HILL QLD 4069 Fax 07 3246 1001 Geomechanics [email protected] Dr K. (Kevin) MCMANUS Box 6060 Tel +643 343 2679 Chair NZGS Riccarton Fax +643 343 2677 [email protected] CHRISTCHURCH NZ Mobile +64 021 211 0048 Ms Imrana Azimullah 51 Staincross Street Tel/Fax (9) 8174786 Secretary NZGS – Corresponding TITIRANGI Auckland, N. Z. [email protected] Member Mr P.B.M (Peter) ROBINSON P O Box 955 Tel 02 9144 7519 AGS Secretariat ST IVES NSW 2075 Mob. 0418 470 367 [email protected] iv Australian Geomechanics Vol 42 No 1 March 2007 CHAIRMAN’S COLUMN We enjoyed another glorious summer in WA with some very mixed reactions to the trial introduction of daylight saving. I am temporarily working in the UK and the winter temperatures in Manchester are a very good advertisement for the Perth climate. LANDSLIDE RISK MANAGEMENT