Australian Geomechanics Society South Australia & Northern Territory – 2002 Meetings

• February 18, 2002

  Site Visit: Southern Metropolitan Coastal Stability

  Lyn Sanders

  In 2001, Golder Associates was engaged by the City of Onkaparinga to assess the risk of instability along its coastline, which runs for around 35 km from Sellicks Beach at its southern end to near the O'Sullivans Beach refinery at its northern. An inspection of the coast from a boat was used as well as the usual ground mapping. Viewing the coast from the boat provided a unique perspective on the landforms and greatly simplified the assessment and comparison of stability along different sections of the coastline. The SA Chapter of the Australian Geomechanics Society retraced this coastal inspection, with Lyn Sanders, Golder's project manager for the risk assessment, providing commentary on the work undertaken, and pointing out areas of interest.The AGS chartered the Temptation - a 55' catamaran for the field trip, which proved to be a luxurious step up from the dusty buses of previous years. The boat cruise ran for approximately 4 hours from 3 pm to 7 pm.

• March 15, 2002

  Construction of the Suez Canal

  Prof. Mamdouh Hamza

  The earliest project to connect the Mediterranean Sea and the Red Sea dates back to 1920 BC. Construction of the Suez Canal, which commenced in 1859, has had a major impact on Egypt's modern history, as it resulted in Egypt becoming bankrupt in 1876, and being occupied in 1882 and later engaged in four wars.. The Lecture will briefly describe some of the many earlier plans for a canal, the history and politics of the current Canal's construction, the engineering challenges, and the enormous obstacles that had to be overcome. More information can be found here.

• April 15, 2002

  Artificial Neural Networks For Settlement Prediction Of Shallow Foundations On Granular Soils

  Mohamed Shahin

  Artificial neural networks (ANNs) are a form of artificial intelligence, which, by means of their architecture, try to simulate the biological structure of the human brain and nervous system. In recent times, ANNs have been applied to many geotechnical engineering tasks and have demonstrated some degree of success. Over the years, many methods have been developed to predict the settlement of shallow foundations on granular soils. However, methods for making such predictions with the required degree of accuracy and consistency have not yet been developed. This can be attributed to the fact that the problem of estimating the settlement of shallow foundations on granular soils is complex and not yet entirely understood as a result of the uncertainty associated with the factors affecting such settlement. Among these factors are the distribution of applied stress, the stress-strain history of granular soils, soil compressibility and the difficulty of obtaining undisturbed samples of granular soils. Inaccurate estimation of settlement of shallow foundations on granular soils may also be due to the fact that most available methods for predicting such settlement are model driven, in which the structure of the model has to be established a priori before the unknown model parameters can be determined. This may potentially compromise model performance, as the form of the equation chosen may be sup-optimal. On the contrary, ANNs are a technique that uses the data a lone to determine the structure of the model as well as the unknown model parameters. Consequently, the need for predefined mathematical equations is negated and as a result, the use of ANNs may overcome the limitations of the existing methods.In the seminar ANNs were described (how they work and what they do) and some ANN applications in the field of geotechnical engineering were demonstrated. The feasibility of using ANNs to obtain more accurate settlement prediction of shallow foundations on granular soils was explored and their performance, with some of the most commonly used traditional methods, compared. The benefits and limitations of ANNs was also discussed.

• May 27, 2002

  E. H. Davis Memorial Lecture: Soil - Structure Interaction

  Assoc. Prof. John Small

  Often there has been a separation in the design of foundations for buildings into the structural component and the foundation. Structural engineers have tended to use simple soil models such as springs to represent the foundation, while foundation engineers have often neglected the foundation stiffness and treated the structural as being perfectly flexible. However, it is often desirable to combine both structural and geotechnical aspects, as this can lead to improved design. In the lecture, some of the issues involved with foundation design were discussed, and some of the limitations of simple techniques were pointed out. Some examples were given of techniques and software that have been developed by the speaker and others to aid in the design of raft foundations and piled-raft foundations. Examples were given of high-rise structures that have been constructed in Germany, the Middle East and in South-east Asia, and some of the advantages of piled-raft foundations were discussed. Although the lecture was mainly concerned with foundation design, it also covered some other topics of interest such as the behaviour of pavements and earth and rockfill dams. Professor John Small is a graduate of King's College London (1972), with a PhD in geomechanics from the University of Sydney in 1977. He has worked for Coffey Partners, the University of Newcastle, and was a Visiting Fellow at the University of Hong Kong in 1982. He joined the University of Sydney in 1983, where he is currently an Associate Professor and Associate Dean of Engineering. He has authored 105 papers in the field of geomechanics, and has a particular interest in numerical analysis of geomechanics and geotechnical software.

• June 17, 2002

  Geotechnical Engineering Aspects of the Bath CSO Project, England

  Matthew Duthy

  In this talk, Matthew Duthy presented a case study of a major civil engineering project with which he was involved while working for Binnie Black & Veatch plc (BB&V) in the United Kingdom. The Bath Combined Sewer Overflow (CSO) Project is an ambitious project to improve the performance of the sewerage system in Bath, England. Driven by regulatory requirements to improve water quality, Wessex Water proposed a major upgrading of sewage collection and treatment west of Bath. The upgrading will involve the need for significantly more hydraulic capacity in the sewerage system, in the form of large underground tunnels and/or storage tanks. One of the main complications and risks for the project is that the proposed works are adjacent to the World Heritage listed Bath city centre with its unique hot thermal springs. It is crucial that the works do not have an adverse impact on the hot springs. In order to mitigate these risks, a comprehensive geotechnical site investigation was commissioned by Wessex Water. BB&V were retained by Wessex Water to act as their lead design consultant (owners engineer) for the scheme, and Matthew Duthy acted as the Resident Engineer for the site investigation. Based on the results of the site investigation, Wessex Water commissioned a comprehensive feasibility study from each of three design and construct civil engineering consortia, in order to identify the preferred elements and layout for construction of the scheme. The talk discussed the regulatory, contractual and technical background to the project and describe the geology and hydrogeology of Bath. The site investigation was outlined, with a particular emphasis on the strategies adopted for obtaining key ground information while safeguarding the integrity of the hot springs. Geotechnical aspects of the feasibility studies by the design and construct consortia were outlined, along with the process of BB&V's assessment of geotechnical aspects of each consortia's submission. Finally, proposed further works for the scheme were outlined. Dr Duthy was educated at Adelaide University and will be well known to many of the SA AGS membership, from his time on the committee (as secretary) prior to his accepting a position with Binnie Black & Veatch plc, in their Surrey office (outside London) in October 1998. Matthew returned to Adelaide in October 2001, and took up his current position as senior geotechnical engineer with URS, and is again active on the AGS committee.

• July 17, 2002

  Annual Half-Day Seminar: Landslide Risk Assessment

  Various

• August 19, 2002

  Geotechnical Engineering Aspects of the Construction of the Barcoo Outlet

  Dr. Peter Mitchell

  The Barcoo stormwater outlet project involved the construction of a cut-and-cover concrete culvert from the waters of the Patawalonga, through the sand dunes at West Beach, to a distance of around 200 m out into the Gulf St Vincent. The precast concrete culvert allows the movement of stormwater from the Patawalonga out to the Gulf. The project represented a major civil engineering undertaking involving the construction of the 6 m high culvert under a public road, under 10 m high sand dunes, and about 8 m under the sea bed. Geotechnical issues faced by the construction included dewatering the highly permeable sand deposits, slope stability of deep cuts through loose, clean sand, bearing capacity and settlement issues for the culvert, sheet piling stability, piping of groundwater, grouting issues, and stabilisation using geotextiles. In his talk, Peter described the geotechnical conditions encountered along the alignment of the culvert and the implications of the ground conditions on the construction. Dr Mitchell will be well known to most AGS members, having presented more than 30 talks to the South Australian Chapter over many years.

• September 16, 2002

  "A Tale of Two Dams" Thorndon Park & Hope Valley

  Andy Parsons, Richard Cavagnaro, Geoff Gosden

  Thorndon Park and Hope Valley Dams were the first and second water supply dams constructed for the City of Adelaide circa 1860 and 1870, respectively. Both dams were constructed in a rural environment without provision to prevent internal erosion (piping) type failures. Thorndon Park is currently part of a City of Campbelltown recreation park and Hope Valley is still part of the SA Water supply network. As the end of the twentieth century approached, both dams had reached their used-by date and were in need of rehabilitation. Andy Parsons first discussed the current state-of-the-art of dam safety evaluation technology and regulations in general terms applicable to all dams. Richard Cavagnaro then described the history and condition of Thorndon Park Dam and as it existed in late 2000, the incident of February 2001 and subsequent draining of the reservoir. Geoff Gosden described the design and construction of the recently completed rehabilitation of the Hope Valley Dam.

• October 14, 2002

  Young Geotechnical Engineers Night and Annual General Meeting

  Aaron O'Malley, Wayne Potter, Wayne Londema, Tom Forde, Tony Polec

  A number of young geotechnical engineering graduates and students will individually give a 10 minute presentation on a range of interesting projects. Members of the Committee will adjudicate and the winner will be presented with a certificate and a $300 cash prize.

  • Aaron O'Malley - Soil moisture and soil movement in an urban development on extremely reactive soil: the first year.
  • Wayne Potter and Wayne Londema - The influence of vegetation on rail track stability.
  • Tom Forde - Geo-environmental management measures at Yongala and Caltowie, South Australia.
  • Tony Polec - Walkley Heights slope stabilisation.
• November 18, 2002

  Visitors Night: Building Faith

  Katharine Bartsch

  Held at: Middle Eastern Cultural House, 126 Henley Beach Rd, Torrensville. Istanbul, Seville, Jerusalem, Delhi...each city conjures a host of images at once exotic, enchanting and mysterious. This richly illustrated presentation explored such cities in relation to the emergence and diffusion of Islam. The emphasis is on architecture. Katherine argued that Islamic architecture is shaped by both an intriguing Muslim heritage and rich cross-cultural encounters.