Search results for: Latest H19-461_V1.0 Exam Questions Vce 🏯 H19-461_V1.0 Labs 🐒 H19-461_V1.0 New Study Plan 🙊 Search for ✔ H19-461_V1.0 ️✔️ on 「 www.pdfvce.com 」 immediately to obtain a free download 🧎H19-461_V1.0 Best Vce
-
Experiences With The Use Of The Conventional Mined Excavation Method In The Santiago Metro – Chile
The Santiago Metro is the largest rapid transit system in South America with 140 km of routes currently in operation. Most of the metro network was developed using the conventional mined excavation method, which was applied for the construction of running tunnels and stations often under shallow overburden conditions and densely built-up urban areas. This paper presents a brief snapshot of the historical evolution of the conventional mined tunnelling methods used for the Santiago Metro underground works, outlining relevant lessons learned along the way and how these cumulative experiences have enabled a continuous improvement and optimisation of design concepts and construction methodologies used for subsequent projects.
-
Thermal efficiency of energy piles in stratified soil under unbalanced operation
Shallow geothermal energy piles are novel and cost-effective heat exchangers used in ground source heat pump systems for heating and cooling buildings. Pile foundations are used to exchange heat with ground besides structural support. Ground thermal conductivity is a decisive design parameter in shallow geothermal applications. Ground homogeneity relying on depth-weighted averaging has been the common assumption in wide research around energy piles in recent years, with soil layering influence remaining mostly unexplored. This becomes particularly important under unbalanced thermal operation, due to thermal accumulation in the ground. To explore this influence, a 3D finite element numerical model is built to solve for the heat conduction-convection multi-physics of energy piles embedded in layered soil. Unbalanced thermal load regimes with different building cooling-to-heating ratios are adopted for long-term assessment, showcasing the effect of this controllable parameter, for soil profiles with different thermal conductivity distributions. Results underscore the necessity to account for the thermal properties’ spatial variability in layered soil and recommend depth-specific thermal conductivity testing under unbalanced thermal load conditions. The thermal performance of the energy pile system in the considered stratified soils is shown to differ from that of their equivalent depth-weighted homogeneous ground owing to the growing difference in the accumulated temperature over the operation life, leading to underpredict the actual thermal conductivity by up to 31.5% as the contrast between layers grows and the unbalanced cooling-to-heating ratios increase. Furthermore, the depth sequence of ground layers of different conductivities is found to be important in predicting the thermal performance of energy piles.
-
Resilient Modulus Of A Stabilised Fine-Grained Subgrade Soil
Mechanistic design methods of pavement structures require the use of elastic moduli for each pavement material including subgrades. In the Austroads pavement design guide (Austroads, 1992), elastic characterisation of subgrades and cemented pavement materials is determined from empirical relationships based on California bearing ratio and unconfined compressive strength, respectively, while repeated load triaxial testing yielding resilient modulus is only mentioned as a recommendation for characterising unbound materials. However, in recent years, the resilient modulus of pavement materials has become a more important parameter in pavement analysis and design. This paper presents some of the findings of a continuing research project on engineering properties of a stabilised fine-grained subgrade soil. In particular, the variations in resilient modulus values due to the changes in additive content, dry density, moisture content and curing time were investigated. Laboratory repeated load triaxial tests yielding resilient moduli were conducted on stabilised fine-grained soil samples simulating the material properties at various levels. The resilient modulus results based on various stress levels were then analysed by using deviator stress and octahedral stress models. Resilient modulus values were calculated for an estimated in-situ stress condition using the octahedral stress model. The relationships between the resilient modulus values and each of the parameters mentioned above were defined by single regression analysis. Also, an equation that helps to estimate resilient modulus as a function of additive content, dry density, moisture content and curing time was established.
-
Risk Based Approach In A Spillway Upgrade
In line with worldwide best practice, major dam upgrades are currently being undertaken in New South Wales (NSW) to ensure the continued safe operation of these assets in line with the Dam Safety Management Guidelines set out by Australian National Committee on Large Dams (ANCOLD) and NSW Dams Safety Committee requirements. Burrendong Dam, which is one of the major dams owned by State Water, is located in the greater Murray Darling River catchment on the upper reaches of the Macquarie River. The dam is currently being upgraded to increase the flood handling capacity of the spillway to cater for extreme flood events.
The conventional spillway design was found to be expensive therefore State Water embarked on a risk based approach to reduce the risk below As Low as Reasonably Practicable (ALARP). Saddle Dam A, which is located approximately 1.5km east of the existing spillway, was considered to be a viable option for an auxiliary spillway. The main issue was, however, the presence of a shear zone containing brecciated rock and clay gouge, which consisted of broadly graded silty sandy gravels and sandy clays. Hence, the potential for piping and foundation erosions were identified as the major risks for the project. The conventional design approach of a traditional concrete apron slab with ground anchors was found to be very expensive. Therefore, the erosion risks for not providing an apron slab to protect the shear zone were thoroughly investigated. The geotechnical conditions were analysed in order to satisfy the nominal criteria for energy dissipation of spillway discharge flows into the natural environment with an acceptable degree of erosion risk. The outcome of this analysis led to a significant reduction in cost as well as risk.
This paper focuses on the analysis and design of the geotechnical aspects adopted in the risk based approach, which led to significant cost savings to the spillway upgrade project. This paper is intended to provide valuable information for geotechnical professionals handling similar types of projects – especially where there is a potential to reduce cost by accepting a risk based approach.
-
Performance and prediction of marine clay treated with vacuum and surcharge consolidation at Port of Brisbane
During the past decade, the application of vacuum preloading for stabilising soft coastal clay and other low-lying estuarine soils has become popular in Australia. The cost-effectiveness is a major factor in most projects in view of the significantly reduced time for achieving a relatively high degree of consolidation. Due to an increase in trade activities at the Port of Brisbane, new facilities on Fisherman Islands at the mouth of the Brisbane River will be constructed on the new outer area (235 ha) adjacent to the existing port facilities via land reclamation. A vacuum assisted surcharge load and conventional surcharge scheme in conjunction with prefabricated vertical drains was selected to reduce the required consolidation time through the deeper subsoil layers. The performance of the combined vacuum and surcharge fill system and the construction of the embankment are described in this paper. A comparison of the performance of the vacuum combined surcharge loading system with a standard surcharge fill highlights the clear benefits of vacuum consolidation. Field monitoring data are presented to demonstrate how the embankment performed during construction. The paper also evaluates the relative performance of the two contrasting preloading systems (i.e. vacuum and nonvacuum system). An analytical solution for radial consolidation considering both time-dependent surcharge loading and vacuum pressure is proposed to predict the settlements and associated excess pore pressures of the soft Holocene clay deposits.
-
Why Aesthetics Needs Early Consideration In Tunnel Design And Excavation – A Case Study From The M8
Road tunnels are more complex than the driving eye would surmise – hidden behind the dark ceilings and colourful wall panels are rock, support bolts, multiple layers of shotcrete, possible water drainage, access passages, fire control systems, electrical systems, and speed cameras. During the design phase of a tunnel project all these components are given significant consideration as they govern the ultimate size of the excavation that is needed. At construction, focus shifts from what will be added to what and how can rock be extracted quickly and safely. The crown and face condition come to the forefront as inputs into the ground support requirements and as short-term prediction of excavation conditions in the following days. Classification of the rock mass is skewed to encapsulate the face, shoulder and crown condition as well as the bolt zone above the crown. Side wall and floor conditions are noted where possible, but visibility is often limited to the current cutting (about 1.5m, with previous cuts already shotcreted) or not possible due to mud and rock waste. Once excavation has progressed, focus shifts to the functionality, endurance and aesthetics the general public will see – the smooth road surface, the painted ceiling with clear road signs, and the architectural panelling on the walls. For the latter two, consideration is required as to how these heavy items will be anchored to the roof and walls. For the M8, the broader face/shoulder/crown rock mass classification was found to be inappropriate to the narrow anchor zone for the architectural panels, which required anchoring specifically at a height 3m above the floor excavation level. This was particularly the case where narrow siltstone beds occurred with the sandstone rock mass and where dykes and shears intersected the tunnels. Fortuitously, compilation mapping including the side walls had been completed for another purpose for the project and was able to be repurposed to assist with panel construction design. Different bolt lengths were required for each rock class in sandstone, shale and dolerite (dykes) with the conditions specific to the zone 3m above the floor level reassessed by experience senior geological staff as the input for the design. A package of works was provided for each wall, indicating the rock class at the anchor zone, both as a map and tabulated. This improved construction sequencing, costing and allowed pre-purchasing of all materials before work commencement. Significant costs would have occurred had the daily mapping not captured the side wall conditions and had compilations been required solely for this purpose.
-
Blasting operations for Tingkillo switching yard to reduce impacts on nearby structures and stakeholders
Blasting operations in high risk areas involve extensive risk assessments and consultation with all stakeholders to minimise impacts on any nearby structures and stakeholders. For the construction of the ElectraNet Tungkillo switching yard in South Australia, blasting operations were undertaken during earthworks to form the switchyard platform which met project delivery dates and reduced the impact of the project on the local environment and stakeholders. The alternative to blasting was the importation of large volumes of fill to the isolated site. The blasting works required detailed design and specialised blasting techniques due to the very high risk of damage to overhead high voltage transmission power lines that provide electricity to the city of Adelaide through the ElectraNet electricity transmission network. In addition to this, nearby property owners expressed concern over potential damage to their properties as a result of the nearby blasting works. Through a complete risk assessment and thorough monitoring program, the blasting works for the Tungkillo switching yard were able to be completed on time, without incident and to design specifications.
-
Advances in offshore and onshore anchoring solutions
The paper presents a snapshot of the research performed within the ARC Centre for Geotechnical Science and Engineering (CGSE) on anchoring systems. The focus is on the determination of nominal bearing factors and the performance of three different types of anchors: the suction embedded plate anchor, the dynamically embedded plate anchor and the helical anchor. The paper emphasises the wide range of analytical, numerical and physical modelling techniques developed within the CGSE to (i) develop a rigorous understanding of the soil-anchor interaction and (ii) create practical tools that can be readily used for design.
-
Urban salinity scoping study for Greater Launceston area: Part 2 Investigation work
The investigation of a pilot study area in the suburban Greater Launceston Area (GLA) has confirmed that soils at a number of sites in the study area have high levels of salinity, much of the salts being readily soluble. The investigation also found medium to extremely saline groundwater conditions throughout the study area. The types of salt in the soil and groundwater are broadly related to two groupings based on the mapped surface geology: (i) Tertiary and undifferentiated sediments; and (ii) dolerite and dolerite derived sediments. Groundwater levels in unconfined and semi confined aquifers generally parallel the local topography, with localised upward and downward flows possible anywhere on the gentle slopes of the pilot study area. Areas of observed salinity impact at the Casino Golf Course and St Patrick’s School sports grounds are related to intense irrigation, construction of water storage ponds (Casino) and cut and fill slope modification (School).
The study concludes that groundwater recharge and seepage in response to rainfall and irrigation contributed to creating artesian conditions in the Tertiary sediments which mobilize in situ salts in areas with upward flow conditions. Specific geological confining conditions probably have less of an impact.
The study has no temporal data to allow an assessment of the effect of changing land use on groundwater levels and quality, and therefore any predictions of areas at risk from future salinity outbreaks have no ‘calibration’ at this stage.
-
RE: Landslide Risk Management Concept And Guidelines Report By AGS Sub-Committee, AGS Journal Vol 35 No 1 March 2000
I am writing to you with my comments on the above paper. The comments arise as the result of work I have been carrying out for the National Parks and Wildlife Service on Risk Assessments for the various lodges and infrastructure development in the Kosciuszko National Park following the Thredbo Landslide. Can you please pass them on to the committee responsible for issue of the report for their consideration.