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Reducing risks in the investigation, design and construction of large concrete dams

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 197-209页

作者： E.T.Brown Golder Associates pty. ltd. BrisbaneAustralia

An overview of the GeoSafe 2016 Symposium topic is provided using the example of large concrete dams for purposes of *** is essential that the risks associated with large dams be evaluated rigorously and managed proactively at all stages of their lives so that the risk of failure remains As Low As Reasonably Practicable(ALARP).Rock engineering features of large concrete dams that require particular attention,assessment and monitoring during the investigation,design,construction,initial filling,inservice operation,and subsequent repair and upgrade stages of the lives of concrete dams are identified and illustrated by examples from recorded experiences.A number of major concrete dam failures,including that of the *** dam,California,U.S.A.,in 1928,have led to significant developments in rock mechanics and rock engineering knowledge and techniques,as well as in dam design and review *** recent advances include a range of analytical,numerical modelling,probabilistic,reliability,failure mode and risk assessment approaches.

关键词： Concrete dam failure Dam engineering Risk assessment Rock engineering design Site investigation

Rock mechanics for design of Brisbane tunnels and implications of recent thinking in relation to rock mass strength

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 676-683页

作者： L.B.McQueen A.Purwodihardjo S.V.L.Barrett Golder Associates pty ltd. 124 Pacific HighwaySt.LeonardsNSW2065Australia Golder Associates pty ltd. 147 Coronation DriveMiltonQueensland4064Australia Golder Associates pty ltd. Building 7Botanicca Corporate Park570 e 588 Swan StreetRichmondVictoria3121Australia

This paper explores the potential implications of recent thinking in relation to rock mass strength for future tunnelling projects in Brisbane,australia,particularly as they are constructed within deep horizons where the in situ stress magnitudes is *** mass failure mechanisms for the current tunnels in Brisbane are generally discontinuity controlled and the potential for stress-induced failure is relatively *** the road tunnels which have been constructed in Brisbane over the last 12 years,the strength of the more massive rock masses for continuum analysis has been estimated by the application of the Hoek-Brown(H-B)failure criterion using the geological strength index(GSI)to determine the H-B parameters mb,s and *** the last few years,alternative approaches to estimating rock mass strength for‘massive to moderately jointed hard rock masses’have been proposed by others,which are built on the work completed by *** and *** in this area over their joint *** paper explores one of these alternative approaches to estimating rock mass strength for one of the geological units(the Brisbane Tuff),which is often encountered in tunnelling projects in *** potential implications of these strength forecasts for future tunnelling projects are discussed along with the additional work which will need to be undertaken to confirm the applicability of such alternative strength criteria for this rock mass.

关键词： Rock mass strength Hoek-Brown(H-B)failure criterion Triaxial testing Brittle failure Brisbane Tuff

CLGA Net:Cross Layer Gated Attention Network for Image Dehazing

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Computers, Materials & Continua 2023年第3期74卷 4667-4684页

作者： Shengchun Wang Baoxuan Huang Tsz Ho Wong Jingui Huang Hong Deng Hunan Normal University Changsha410006China Z-emotion pty ltd. Victoria3178Australia

In this paper,we propose an end-to-end cross-layer gated attention network(CLGA-Net)to directly restore fog-free *** with the previous dehazing network,the dehazing model presented in this paper uses the smooth cavity convolution and local residual module as the feature extractor,combined with the channel attention mechanism,to better extract the restored features.A large amount of experimental data proves that the defogging model proposed in this paper is superior to previous defogging technologies in terms of structure similarity index(SSIM),peak signal to noise ratio(PSNR)and subjective visual *** order to improve the efficiency of decoding and encoding,we also describe a fusion residualmodule and conduct ablation experiments,which prove that the fusion residual is suitable for the dehazing ***,we use fusion residual as a fixed module for encoding and *** addition,we found that the traditional defogging model based on the U-net network may cause some information losses in *** have achieved effective maintenance of low-level feature information through the cross-layer gating structure that better takes into account global and subtle *** also present the application of our CLGA-Net in challenging scenarios where the best results in both quantity and quality can be *** results indicate that the present cross-layer gating module can be widely used in the same type of network.

关键词： Deep learning dehazing image restoration end to end

Design,Development and Testing of the JTech Bolt for Use in Static,Quasi-Static and Dynamic Domains

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Journal of Civil Engineering and Architecture 2024年第6期18卷 282-295页

作者： Trent Roberts jennmar australia pty ltd. 40-44 Anzac Avenue Smeaton Grange NSW 2567Australia

Designing a rock reinforcement element requires knowledge of:geomechanical behaviour,interaction of the reinforcement element with rock mass and the element’s mechanistic response in static and dynamic *** this knowledge the JTech bolt was developed and subjected to a thorough program to test,gather data and validate the bolt performance in varying *** conducting FE(finite element)modeling,the simulation reviews the JTech bolt design evaluating the effects of threadbar geometric variation,threadbar and nut engagement results under high stress,coating friction response and effects of thread tolerance extremes on the failure *** results determine safety factors,tolerances and quality management *** manufactured,in-situ system testing,laboratory and underground short encapsulation testing,resin mixing testing,double shear testing and dynamic testing at varying velocity and mass,determine the system’s capacity and effectiveness in static,quasi-static and dynamic mining *** this paper,the process and results are described.

关键词： Rock reinforcement geomechanical behavior static quasi-static dynamic domains

A review of energy associated with coal bursts

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International Journal of Mining Science and Technology 2018年第5期28卷 755-761页

作者： Winton J.Gale SCT Operations pty ltd WollongongNSW 2500Australia

A coal burst is defined as a rapid expulsion of coal(and potentially gas) from the boundary of the roadway. Rock and coal fractures together with micro seismic vibration is a common occurrence during mining, however, it is very uncommon for coal and rock to be propelled into the roadway. Irrespective, such occurrences do occur and appear to require significantly more energy than is available from strain energy release during coal cutting. The sources of energy which can contribute to the propulsion of coal from the face or ribs are typically strain energy from the surrounding ground, seismic energy from a rapid rupture of the ground in the vicinity, or rapid expansion of gas from within the burst source area. The aim of this paper is to briefly review the bursts which may be related to strain energy, seismic energy and gas energy.

关键词： Coal burst Strain energy Gas energy Seismic energy Pillar stability

Vulnerability of Regional Aviation Networks Based on DBSCAN and Complex Networks

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Computer Systems Science & Engineering 2022年第11期43卷 643-655页

作者： Hang He Wanggen Liu Zhenhan Zhao Shan Heand Jinghui Zhang Civil Aviation Flight University of China Guanghan618307China Webchain pty ltd. SydneyNSW2118Australia

To enhance the accuracy of performance analysis of regional airline network,this study applies complex network theory and Density-Based Spatial Clustering of Applications with Noise(DBSCAN)algorithm to investigate the topology of regional airline network,constructs node importance index system,and clusters 161 airport nodes of regional airline ***,entropy power method and approximating ideal solution method(TOPSIS)is applied to comprehensively evaluate the importance of airport nodes and complete the classification of nodes and identification of key points;adopt network efficiency,maximum connectivity subgraph and network connectivity as vulnerability measurement indexes,and observe the changes of vulnerability indexes of key nodes under deliberate attacks and 137 nodes under random *** results demonstrate that the decreasing trend of the maximum connectivity subgraph indicator is slower and the decreasing trend of the network efficiency and connectivity indicators is faster when the critical nodes of the regional airline network are deliberately ***,the decreasing trend of the network efficiency indicator is faster and the decreasing trend of the maximum connectivity subgraph indicator is slower when the nodes of four different categories are randomly ***,it is proposed to identify and focus on protecting critical nodes in order to better improve the security level of regional airline system.

关键词： DBSCAN algorithm regional airlines key node vulnerability

On-site stormwater detention for australian development projects: Does it meet frequent flow management objectives?

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Water Science and Engineering 2019年第1期12卷 1-10页

作者： Rodney Ronalds Alex Rowlands Hong Zhang School of Engineering and Built Environment Griffith University Gold Coast 4216 Australia Michael Bale & Associates pty ltd. Gold Coast 4216 Australia

On-site stormwater detention (OSD) is a conventional component of urban drainage systems, designed with the intention of mitigating the increase to peak discharge of stormwater runoff that inevitably results from urbanization. In australia, singular temporal patterns for design storms have governed the inputs of hydrograph generation and in turn the design process of OSD for the last three decades. This paper raises the concern that many existing OSD systems designed using the singular temporal pattern for design storms may not be achieving their stated objectives when they are assessed against a variety of alternative temporal patterns. The performance of twenty real OSD systems was investigated using two methods:(1) ensembles of design temporal patterns prescribed in the latest version of australian Rainfall and Runoff, and (2) real recorded rainfall data taken from pluviograph stations modeled with continuous simulation. It is shown conclusively that the use of singular temporal patterns is ineffective in providing assurance that an OSD will mitigate the increase to peak discharge for all possible storm events. Ensemble analysis is shown to provide improved results. However, it also falls short of providing any guarantee in the face of naturally occurring rainfall.

关键词： Stormwater detention Frequent flow management Temporal patterns Runoff routing Continuous simulation South East Queensland

Cooling pathways for deep australian longwall coal mines of the future

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International Journal of Mining Science and Technology 2018年第6期28卷 865-875页

作者： B.Belle M.Biffi Anglo American Coal QueenslandAustralia Department of Mining Engineering UNSWSydneyNSW 2052Australia Anglo American Operations(pty)ltd. Johannesburg 2001South Africa

Cooling of coal mines in the Bowen Basin, characterized by steep geothermal gradient, is presently achieved mostly through rental surface bulk air cooling in summer months. This paper argues that future mines will be required to focus their cooling resources more intensively to manage a challenging thermal environment where virgin coal temperatures over 50 °C at a depth of 500 m are expected. Currently, mine cooling systems are employed to maintain the wet bulb temperatures(WBT) to below 27 °C at which point the risks of heat stroke or other heat related issues are manageable. The capacities of these systems are in the range of 6–10 MW refrigeration power. The relationship between high working temperature environment and injury frequency rates is well established. Therefore, provision of appropriate cooling strategies and understanding their optimum performance and suitability are important to australian coal mines of the future. This paper evaluates the underground temperature profiles of deep, gassy coal mines with propensity for spontaneous combustion and proposes the long term cooling pathways to effectively manage the thermal hazards. Thermodynamic modeling is performed on a longwall face and includes air leakage effects from goaf streams at various locations along the longwall face. The strategy summarizes the application of underground bulk air cooling, chilled water sprays on the shearer and the resulting temperature profiles. Considering the new mining projects planned for the Bowen Basin region, a review of implementable cooling strategies such as mid-gate mobile bulk air coolers(BACs), spot coolers, underground bulk air cooling and the use of chilled water to enhance the positional efficiency of cooling plants,are discussed in this paper. Finally, the comparison of ‘rental' versus ‘ownership' of cooling plants is analysed as part of long-term cooling strategies.

关键词： Cooling Chilled water Underground Positional efficiency Thermal hazard

Analysis and design of axially loaded piles in rock

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第3期11卷 535-548页

作者： C.M.Haberfield A.L.E.Lochaden Golder Associates pty.ltd. MelbourneAustralia

Despite significant advancements in in situ test techniques,construction practices,understanding of rock joint and rock mass behaviours,and numerical analysis methods,the design of bored concrete cast-insitu piles in rock is still largely based on the assessment of bearing ***,for many of the rock conditions encountered,the bearing capacity of piles is a nebulous concept and a figment of the designer’s *** if it can be reasonably quantified,it has little,if any,significance to the performance of a pile in *** load carrying capacity of even low strength rock(in most situations)is far in excess of the strength of the structure(for example,a building column)transmitting the *** performance of a pile in rock is usually a displacement issue and is a function of rock mass stiffness rather than rock mass *** addition,poor pile performance is much more likely to result from poor construction practices than excessive displacement of the rock *** occur for footings that are undermined,or where unfavourable structure in the rock allows movement towards a free surface to ***,codes of practices,reference books and other sources of design information should focus foundation design in rock on displacement rather than strength *** investigations should measure rock mass stiffness and defect properties,as well as intact rock *** paper summarises the fundamental concepts relating to performance of piles in rock and provides a basis for displacement focused design of piles in *** also presents comments relating to how piles are modelled in widely used commercial finite element software for soil-structure interaction analysis,within the context of the back-analysis of a pile load test,and proposes recommendations for pile analysis and design.

关键词： Pile design Pile analysis Pile load test Finite element analysis