The Department of Transport and Main Roads (TMR), Engineering and Technology's (E&T) Geotechnical Section, have completed a research-based field trial aimed at developing a repeatable methodology to carry out geotechnical boreholes on steeply sloping ground. This has been presented in the context of slope failures, whereby the utilisation of this practise will provide subsurface information, which is directly representative of the area of interest, rather than that which is outside the landslide extent (current general practise within Australia). It is expected that the information gained from adopting this practice will enable optimum design and remediation treatments for landslides within Australia, and subsequently contribute strongly to sustainable project outcomes.
{"title":"Borehole investigation on steep sloping ground","authors":"Jun Sugawara, Daniel Colborne, Mogana Sundaram","doi":"10.56295/agj5823","DOIUrl":"https://doi.org/10.56295/agj5823","url":null,"abstract":"The Department of Transport and Main Roads (TMR), Engineering and Technology's (E&T) Geotechnical Section, have completed a research-based field trial aimed at developing a repeatable methodology to carry out geotechnical boreholes on steeply sloping ground. This has been presented in the context of slope failures, whereby the utilisation of this practise will provide subsurface information, which is directly representative of the area of interest, rather than that which is outside the landslide extent (current general practise within Australia). It is expected that the information gained from adopting this practice will enable optimum design and remediation treatments for landslides within Australia, and subsequently contribute strongly to sustainable project outcomes.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":"48 15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135983147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To support our civilisation’s requirement for carbon steel, longwall mining of the Bulli Seam at Appin and Tahmoor Collieries has occurred to recover high quality coking/metallurgical coal, being for steelmaking. The Main Southern Railway crosses the footprint of both mines, and it was therefore important to manage the risk to infrastructure and public safety during longwall retreat in this strain-driven environment. One technical issue is the response to subsidence-induced ‘valley closure’. This has occurred in both gently undulating Wianamatta Group Ashfield Shale and the steeper upper Hawkesbury Sandstone valleys. This paper covers the observed responses of embankments on the Main Southern Railway and the heritage railway Picton to Mittagong Loop Line, and illustrates the responses of the embankments to valley closure that produced up to 11% strain, as well as illustrating displacement field development and derived principal strain vectors. The responses of four embankments are presented beneath which longwalls have been successfully extracted, and done so without adverse impact upon public safety. An understanding of the strain-driven responses of the embankments is presented.
{"title":"Responses Of Free-Standing Railway Embankments As A Consequence Of Mine Subsidence In The NSW Southern Coalfield","authors":"A. Leventhal, T. Hull, R. Walsh, Ross Barber","doi":"10.56295/agj5813","DOIUrl":"https://doi.org/10.56295/agj5813","url":null,"abstract":"To support our civilisation’s requirement for carbon steel, longwall mining of the Bulli Seam at Appin and Tahmoor Collieries has occurred to recover high quality coking/metallurgical coal, being for steelmaking. The Main Southern Railway crosses the footprint of both mines, and it was therefore important to manage the risk to infrastructure and public safety during longwall retreat in this strain-driven environment. One technical issue is the response to subsidence-induced ‘valley closure’. This has occurred in both gently undulating Wianamatta Group Ashfield Shale and the steeper upper Hawkesbury Sandstone valleys. This paper covers the observed responses of embankments on the Main Southern Railway and the heritage railway Picton to Mittagong Loop Line, and illustrates the responses of the embankments to valley closure that produced up to 11% strain, as well as illustrating displacement field development and derived principal strain vectors. The responses of four embankments are presented beneath which longwalls have been successfully extracted, and done so without adverse impact upon public safety. An understanding of the strain-driven responses of the embankments is presented.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44600853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sugarcane is the second largest export crop in Australia. Industrial production of sugar, from sugarcane, results in bagasse fly ash (BFA), a by-product from the cogeneration in sugar milling operations that generate electricity by steam. The chemical and physical properties of BFA highlight its potential as a promising pozzolan for the stabilization of expansive soils, due primarily to a high content and surface area of the amorphous silicate found in BFA. Silicate in bagasse fly ash reacts extensively with calcium hydrate in lime to produce hydrated products via pozzolanic reactions, this results in a hardening of the material to which BFA and lime have been added. This reaction has been studied to be a function of the size of BFA particles and conditions of the curing process. This study explored the variables that influence the reaction and evaluated shrinkage and compressive strength of the mixtures to which bagasse fly ash, in the form of different particle size distributions, and hydrated lime are added. The maximum BFA particles sizes considered within this study include 75, 150 and 425 μm; curing times of 7 and 28 days are also explored. A suite of testing, including Atterberg limits, linear shrinkage (LS), and unconfined compressive strength (UCS) tests were completed on the prepared mixtures. The findings indicate that bagasse fly ash with a maximum size of 425 μm yields a higher UCS and lower LS, compared to finer BFA particle mixtures. The ash with a maximum particle size of 425-μm also improves the ductility of treated soils and accelerates their strength gain, compared to soil- lime stabilized samples. The results of the study build towards a better understanding of BFA, and the ways in which such a material maybe engineered to replace concrete in road work projects and other applications involving expansive soils.
{"title":"The Influence Of Bagasse Fly Ash Particle Size In Controlling Expansive Soils In Combination With Hydrated Lime","authors":"T. Le, Sachit A. J. Desa, H. Khabbaz","doi":"10.56295/agj5812","DOIUrl":"https://doi.org/10.56295/agj5812","url":null,"abstract":"Sugarcane is the second largest export crop in Australia. Industrial production of sugar, from sugarcane, results in bagasse fly ash (BFA), a by-product from the cogeneration in sugar milling operations that generate electricity by steam. The chemical and physical properties of BFA highlight its potential as a promising pozzolan for the stabilization of expansive soils, due primarily to a high content and surface area of the amorphous silicate found in BFA. Silicate in bagasse fly ash reacts extensively with calcium hydrate in lime to produce hydrated products via pozzolanic reactions, this results in a hardening of the material to which BFA and lime have been added. This reaction has been studied to be a function of the size of BFA particles and conditions of the curing process. This study explored the variables that influence the reaction and evaluated shrinkage and compressive strength of the mixtures to which bagasse fly ash, in the form of different particle size distributions, and hydrated lime are added. The maximum BFA particles sizes considered within this study include 75, 150 and 425 μm; curing times of 7 and 28 days are also explored. A suite of testing, including Atterberg limits, linear shrinkage (LS), and unconfined compressive strength (UCS) tests were completed on the prepared mixtures. The findings indicate that bagasse fly ash with a maximum size of 425 μm yields a higher UCS and lower LS, compared to finer BFA particle mixtures. The ash with a maximum particle size of 425-μm also improves the ductility of treated soils and accelerates their strength gain, compared to soil- lime stabilized samples. The results of the study build towards a better understanding of BFA, and the ways in which such a material maybe engineered to replace concrete in road work projects and other applications involving expansive soils.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49486221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The use of biopolymers to enhance the engineering properties of soil has received increasing attention in recent years, however, the interactive role that biopolymers and the fines content of the soil play in governing the geotechnical parameters still requires insightful investigation, in relation to chemical soil treatment that can be ecologically detrimental. This paper examines the combined effects of Xanthan Gum (XG) derived from specific bacterial strains and the presence of clay fines content (kaolin) on the strength and stiffness of low plasticity soils, with special reference of cyclic traffic (road and rail) loading. In this study, fine sand is mixed with different contents of kaolin, whereby laboratory compression and tensile tests were conducted on natural (untreated) and XG-treated soil specimens. The results indicate that soil strength can be enhanced significantly when XG is added, however the effectiveness is a function of the kaolin content (KC). At an optimum XG content of 2% and a fines content increasing from 5% to 30%, split tensile strength increases from 230 to 750 kPa,while the unconfined compressive strength rises from 1.4 to 7.9 MPa, respectively. For XG content between 0.5% and 2%, the small strain stiffness of treated soil increases fourfold from 206 to 854 MPa.
{"title":"Effects Of Fines Content On The Strength And Stiffness Of Biopolymer Treated Low-Plasticity Soils","authors":"R. Gedela, B. Indraratna, S. Medawela, T. Nguyen","doi":"10.56295/agj5811","DOIUrl":"https://doi.org/10.56295/agj5811","url":null,"abstract":"The use of biopolymers to enhance the engineering properties of soil has received increasing attention in recent years, however, the interactive role that biopolymers and the fines content of the soil play in governing the geotechnical parameters still requires insightful investigation, in relation to chemical soil treatment that can be ecologically detrimental. This paper examines the combined effects of Xanthan Gum (XG) derived from specific bacterial strains and the presence of clay fines content (kaolin) on the strength and stiffness of low plasticity soils, with special reference of cyclic traffic (road and rail) loading. In this study, fine sand is mixed with different contents of kaolin, whereby laboratory compression and tensile tests were conducted on natural (untreated) and XG-treated soil specimens. The results indicate that soil strength can be enhanced significantly when XG is added, however the effectiveness is a function of the kaolin content (KC). At an optimum XG content of 2% and a fines content increasing from 5% to 30%, split tensile strength increases from 230 to 750 kPa,while the unconfined compressive strength rises from 1.4 to 7.9 MPa, respectively. For XG content between 0.5% and 2%, the small strain stiffness of treated soil increases fourfold from 206 to 854 MPa.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44277093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Over the last one hundred years, tailings dams have failed globally at a rate of 2 to 5 per annum. This failure rate is considered unacceptable by the community and by the mining industry. The conventional transport of slurry or thickened tailings and their storage in a tailings dam, requires low capital and operational expenditure, as slurry tailings can be transported by pipeline using relatively inexpensive and robust centrifugal pumps. Recently, the filtration of tailings, their transport by conveyor or truck, and “dry” stacking have been seen as an alternate method of tailings management. However, filtration and dry stacking are considered expensive. Over the full life cycle, including post-closure, of filtration and a dry stack facility, the potential to increase water recovery for recycling and increased options post-closure can lead to a reduction in the total expense of a dry stack facility. This study aimed to contribute to understanding of the cost-effectiveness of tailings dewatering and dry stacking as a tailings management method. Various tailings samples from different locations and with different characteristics were tested for their filtration potential. The potential for monetary savings through the reuse/recycling of the water recovered from the tailings through filtration was a particular focus. While tailings with higher clay mineral contents had more potential for water recovery than coarser-grained tailings, they were also more difficult to dewater. Tailings with lower clay mineral contents were relatively easy to dewater, requiring a short residence time, leading to increased water recovery and volume reduction potential. The results identified that there is significant potential for water recovery, leading to monetary savings through the reuse/recycling of water, potential for storage volume reduction, and potential for higher value post-closure uses.
{"title":"Cost-Effectiveness Of Tailings Dewatering And Stacking","authors":"Sophie Flottmann, David Williams, Danish Kazmi","doi":"10.56295/agj5814","DOIUrl":"https://doi.org/10.56295/agj5814","url":null,"abstract":"Over the last one hundred years, tailings dams have failed globally at a rate of 2 to 5 per annum. This failure rate is considered unacceptable by the community and by the mining industry. The conventional transport of slurry or thickened tailings and their storage in a tailings dam, requires low capital and operational expenditure, as slurry tailings can be transported by pipeline using relatively inexpensive and robust centrifugal pumps. Recently, the filtration of tailings, their transport by conveyor or truck, and “dry” stacking have been seen as an alternate method of tailings management. However, filtration and dry stacking are considered expensive. Over the full life cycle, including post-closure, of filtration and a dry stack facility, the potential to increase water recovery for recycling and increased options post-closure can lead to a reduction in the total expense of a dry stack facility. This study aimed to contribute to understanding of the cost-effectiveness of tailings dewatering and dry stacking as a tailings management method. Various tailings samples from different locations and with different characteristics were tested for their filtration potential. The potential for monetary savings through the reuse/recycling of the water recovered from the tailings through filtration was a particular focus. While tailings with higher clay mineral contents had more potential for water recovery than coarser-grained tailings, they were also more difficult to dewater. Tailings with lower clay mineral contents were relatively easy to dewater, requiring a short residence time, leading to increased water recovery and volume reduction potential. The results identified that there is significant potential for water recovery, leading to monetary savings through the reuse/recycling of water, potential for storage volume reduction, and potential for higher value post-closure uses.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44358074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In a standard deterministic analysis discrete scenarios are considered, and a moderately conservative “characteristic” value is used as a design basis. However, fixed or exact values in a real-world geotechnical site seldom occurs. Deterministic approaches may not explicitly consider the ground uncertainty. Simulations using various probabilities provides for this uncertainty as each parameter input is treated as a random variable within certain measured ranges or ability to evaluate. Monte Carlo (MC) sampling is a traditional technique for generating random numbers to sample from a probability distribution. When low probability events occur, a small number of MC iterations might not sample sufficient quantities of these outcomes for inclusion in the simulation model. Latin Hypercube (LH) sampling uses stratification of the input probability distributions, to overcome the limitations of Monte Carlo sampling. The simulation results show low probability outcomes are included in the sampling for the simulation model. At a high number of simulation iterations both provide similar outputs, but at low simulation iterations the LH is more reliable. However, both the MC and LH sampling suffer from impractical values at low or high probability events when the normal probability density function (PDF) is adopted. The normal PDF is commonly used in statistical modelling. Non-normal PDFs often represent the best fit PDF when a goodness of fit test is carried out. The errors associated with using the common normal PDF are shown with the above-mentioned simulation models. This best fit PDF applies whether simulation models as described above is used or even with simple “what if” sensitivity models in traditional analysis.
{"title":"Managing Geotechnical Uncertainty With Simulation Models: An Introduction","authors":"B. Look","doi":"10.56295/agj5741","DOIUrl":"https://doi.org/10.56295/agj5741","url":null,"abstract":"In a standard deterministic analysis discrete scenarios are considered, and a moderately conservative “characteristic” value is used as a design basis. However, fixed or exact values in a real-world geotechnical site seldom occurs. Deterministic approaches may not explicitly consider the ground uncertainty. Simulations using various probabilities provides for this uncertainty as each parameter input is treated as a random variable within certain measured ranges or ability to evaluate. Monte Carlo (MC) sampling is a traditional technique for generating random numbers to sample from a probability distribution. When low probability events occur, a small number of MC iterations might not sample sufficient quantities of these outcomes for inclusion in the simulation model. Latin Hypercube (LH) sampling uses stratification of the input probability distributions, to overcome the limitations of Monte Carlo sampling. The simulation results show low probability outcomes are included in the sampling for the simulation model. At a high number of simulation iterations both provide similar outputs, but at low simulation iterations the LH is more reliable. However, both the MC and LH sampling suffer from impractical values at low or high probability events when the normal probability density function (PDF) is adopted. The normal PDF is commonly used in statistical modelling. Non-normal PDFs often represent the best fit PDF when a goodness of fit test is carried out. The errors associated with using the common normal PDF are shown with the above-mentioned simulation models. This best fit PDF applies whether simulation models as described above is used or even with simple “what if” sensitivity models in traditional analysis.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49458233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ralph E Cammack, R. Bertuzzi, Adrian P. L. Smith, R. Brehaut
Rock mass parameters are presented for the typical range of rock conditions encountered in the Brisbane CBD and surrounding area. Rock mass units are classified based on lithology, weathering, intact rock strength and degree of disturbance. The rock mass parameters are based on the Author’s combined experience from Brisbane infrastructure projects including the M7 Clem Jones Tunnel, Airport Link and Cross River Rail. The parameters may be useful for design and construction of future ground engineering projects in Brisbane.
{"title":"Rock Mass Parameters For The Brisbane CBD","authors":"Ralph E Cammack, R. Bertuzzi, Adrian P. L. Smith, R. Brehaut","doi":"10.56295/agj5742","DOIUrl":"https://doi.org/10.56295/agj5742","url":null,"abstract":"Rock mass parameters are presented for the typical range of rock conditions encountered in the Brisbane CBD and surrounding area. Rock mass units are classified based on lithology, weathering, intact rock strength and degree of disturbance. The rock mass parameters are based on the Author’s combined experience from Brisbane infrastructure projects including the M7 Clem Jones Tunnel, Airport Link and Cross River Rail. The parameters may be useful for design and construction of future ground engineering projects in Brisbane.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":"1 1","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41398663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Metro Tunnel Project is delivering twin nine-kilometre rail tunnels in Melbourne, Australia. In addition to the tunnels, five new underground stations are being constructed. Two of the new stations – State Library and Town Hall – are complex cavern and adit excavations located in Melbourne’s City Centre which will directly connect to the existing City Loop Stations. The State Library station, located predominantly underneath Swanston Street and a busy tram route, was surrounded by a mixture of modern, educational and heritage developments requiring the excavation sequence and primary support to be designed to ensure minimal surface impacts. To simulate the anisotropic rock mass response to the excavation of the State Library Station, FLAC3D numerical analysis was undertaken. The analysis adopted the ubiquitous joint constitutive model approach and was used to assess the performance of the primary lining design and to determine the impacts the predicted ground displacements may have on the surrounding structures.
{"title":"Melbourne Metro Tunnel Project - Numerical Analysis Of Anisotropic Rock Mass For State Library Station","authors":"Ben Coombes, R. Storry, D. Sainsbury","doi":"10.56295/agj5743","DOIUrl":"https://doi.org/10.56295/agj5743","url":null,"abstract":"The Metro Tunnel Project is delivering twin nine-kilometre rail tunnels in Melbourne, Australia. In addition to the tunnels, five new underground stations are being constructed. Two of the new stations – State Library and Town Hall – are complex cavern and adit excavations located in Melbourne’s City Centre which will directly connect to the existing City Loop Stations. The State Library station, located predominantly underneath Swanston Street and a busy tram route, was surrounded by a mixture of modern, educational and heritage developments requiring the excavation sequence and primary support to be designed to ensure minimal surface impacts. To simulate the anisotropic rock mass response to the excavation of the State Library Station, FLAC3D numerical analysis was undertaken. The analysis adopted the ubiquitous joint constitutive model approach and was used to assess the performance of the primary lining design and to determine the impacts the predicted ground displacements may have on the surrounding structures.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42998012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Rozelle Interchange Project (RIC) in Sydney is an underground motorway interchange connecting multiple underground and surface arterial roads as well as the future Western Harbour Tunnel and Beaches Link. RIC completes the WestConnex program of works and is a complex array of approximately 22 km of multiple level tunnels, all constructed in an area 2.5 km long and 1.5 km wide. RIC is located within complex ground conditions that include deep soils, regional faults, structural zones and igneous intrusions. Deep natural soils infilling a valley near Rozelle Bay are mostly recent Holocene alluvial, marginal marine and marine deposits. These soils are interlayered, discontinuous, normally to slightly over consolidated and capped by sand and coarse rockfill from 19th century reclamation. There is a strong contrast in the level of detail between borehole and CPT data. Distilling this to provide a geological and geotechnical model for a project wide interpretive report for designers of multiple structures required a hybrid approach to model presentation. This included providing a simplified graphical model and including details from specific investigations and laboratory testing allowing designers flexibility to adopt appropriate parameters for their specific application. Similarly, the rock structural model evolved from development of structural domains to identification and inclusion of regional geological structures overprinting the structural model. Regional scale thrust faults, corridors of structural complexity and igneous intrusions were identified and refined prior to and throughout the design process. These were considered in the design by modification of excavation sequencing and changes to tunnel support. Tunnel excavations encountered these regional features at the locations predicted and with similar character as those described in the model allowing the safe construction of the tunnels.
{"title":"Characterisation Of Complex Ground Conditions For The Rozelle Interchange Project","authors":"B. Estrada, T. Nash, Andrew de Ambrosis, I. Chan","doi":"10.56295/agj5746","DOIUrl":"https://doi.org/10.56295/agj5746","url":null,"abstract":"The Rozelle Interchange Project (RIC) in Sydney is an underground motorway interchange connecting multiple underground and surface arterial roads as well as the future Western Harbour Tunnel and Beaches Link. RIC completes the WestConnex program of works and is a complex array of approximately 22 km of multiple level tunnels, all constructed in an area 2.5 km long and 1.5 km wide. RIC is located within complex ground conditions that include deep soils, regional faults, structural zones and igneous intrusions. Deep natural soils infilling a valley near Rozelle Bay are mostly recent Holocene alluvial, marginal marine and marine deposits. These soils are interlayered, discontinuous, normally to slightly over consolidated and capped by sand and coarse rockfill from 19th century reclamation. There is a strong contrast in the level of detail between borehole and CPT data. Distilling this to provide a geological and geotechnical model for a project wide interpretive report for designers of multiple structures required a hybrid approach to model presentation. This included providing a simplified graphical model and including details from specific investigations and laboratory testing allowing designers flexibility to adopt appropriate parameters for their specific application. Similarly, the rock structural model evolved from development of structural domains to identification and inclusion of regional geological structures overprinting the structural model. Regional scale thrust faults, corridors of structural complexity and igneous intrusions were identified and refined prior to and throughout the design process. These were considered in the design by modification of excavation sequencing and changes to tunnel support. Tunnel excavations encountered these regional features at the locations predicted and with similar character as those described in the model allowing the safe construction of the tunnels.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45890868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bernard Shen, Strath Clarke, A. Rogan, P. McCormack
The new Roma Street underground railway station in Brisbane is being constructed as part of Cross River Rail’s Tunnel, Stations and Development (TSD) package. The joint venture of CPB Contractors, BAM International Australia, Ghella and UGL (CBGU JV) is building the 5.9km long twin tunnels from the Southern Tunnel Portal near Dutton Park station, beneath the Brisbane River and CBD to the Northern Tunnel Portal in Spring Hill. The Cross River Rail project includes excavation and construction of four new underground stations. Roma Street station comprises a 280m long cavern, five smaller connecting tunnels (adits) and three shafts. The station cavern has an excavated span of up to 24.4m with approximately 15m rock cover. It has been excavated within the Neranleigh-Fernvale Group (NFG) rock mass, which comprises weakly metamorphosed sandstone (meta-greywacke and arenite), phyllite and subordinate quartzite and meta-basalt. The station lies within the regional Normanby Fault Zone, characterised by a major fault up to 20m wide comprising a combination of intact rock, rock breccia and clay gouge. The fault zone encountered during the station cavern excavation required heavier primary support and localised foundation treatment. The initial primary (temporary) support of the cavern and adits comprised rock bolts, cable bolts and a thin synthetic fibre-reinforced shotcrete lining. In some areas a passive shotcrete arch lining was required. Overlying piled footings from an existing busway overpass structure were within a metre of the adits’ excavated profile which necessitated a complex load transfer structure at the surface and verification of pile toe levels during tunnel construction. The cavern permanent lining typically comprises steel fibre-reinforced concrete in the crown, bar reinforced concrete for the sidewalls, and bar and steel fibre-reinforced concrete invert slabs. Bar reinforcement is used in the cavern crown where it intersects the adits. Ground loads for the permanent structure had to consider the influence of future developments. This paper presents some of the challenges of the primary support and permanent lining design of the station cavern and adits. It summarises the as-encountered ground conditions, aspects of the primary support and permanent lining design that were geotechnically challenging and the solutions developed to meet the project requirements.
{"title":"Design And Construction Of Roma Street Station Cavern, Cross River Rail, Brisbane","authors":"Bernard Shen, Strath Clarke, A. Rogan, P. McCormack","doi":"10.56295/agj5744","DOIUrl":"https://doi.org/10.56295/agj5744","url":null,"abstract":"The new Roma Street underground railway station in Brisbane is being constructed as part of Cross River Rail’s Tunnel, Stations and Development (TSD) package. The joint venture of CPB Contractors, BAM International Australia, Ghella and UGL (CBGU JV) is building the 5.9km long twin tunnels from the Southern Tunnel Portal near Dutton Park station, beneath the Brisbane River and CBD to the Northern Tunnel Portal in Spring Hill. The Cross River Rail project includes excavation and construction of four new underground stations. Roma Street station comprises a 280m long cavern, five smaller connecting tunnels (adits) and three shafts. The station cavern has an excavated span of up to 24.4m with approximately 15m rock cover. It has been excavated within the Neranleigh-Fernvale Group (NFG) rock mass, which comprises weakly metamorphosed sandstone (meta-greywacke and arenite), phyllite and subordinate quartzite and meta-basalt. The station lies within the regional Normanby Fault Zone, characterised by a major fault up to 20m wide comprising a combination of intact rock, rock breccia and clay gouge. The fault zone encountered during the station cavern excavation required heavier primary support and localised foundation treatment. The initial primary (temporary) support of the cavern and adits comprised rock bolts, cable bolts and a thin synthetic fibre-reinforced shotcrete lining. In some areas a passive shotcrete arch lining was required. Overlying piled footings from an existing busway overpass structure were within a metre of the adits’ excavated profile which necessitated a complex load transfer structure at the surface and verification of pile toe levels during tunnel construction. The cavern permanent lining typically comprises steel fibre-reinforced concrete in the crown, bar reinforced concrete for the sidewalls, and bar and steel fibre-reinforced concrete invert slabs. Bar reinforcement is used in the cavern crown where it intersects the adits. Ground loads for the permanent structure had to consider the influence of future developments. This paper presents some of the challenges of the primary support and permanent lining design of the station cavern and adits. It summarises the as-encountered ground conditions, aspects of the primary support and permanent lining design that were geotechnically challenging and the solutions developed to meet the project requirements.","PeriodicalId":43619,"journal":{"name":"Australian Geomechanics Journal","volume":" ","pages":""},"PeriodicalIF":0.2,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46838532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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