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By Clara Godoy, Paulo Couceiro, Juan Navarro

The continuous automatization and digitalization of the different stages involved in any underground construction bring new possibilities to optimize the operation. One of the most important requirements for the development of these projects consist of a proper rock mass characterization for optimizing the stages of the drilling, blasting and support cycle. In the last few years the road to digitalization has gone through data science and big data, showing the importance of data gathered to describe the geological and geotechnical environment that surrounds the operations. Since rock characteristics have an important influence in the drilling response, the technological advances in the sensorization of drilling machinery such as the Measurement While Drilling system (MWD) allow to gather the necessary amount of information to be applied in data science processes to evaluate changes in the rock mass with higher resolution than conventional methods. In this paper, Machine Learning techniques have been used to combine data monitored from the drill rigwith scanner profiles of the excavated sections to develop an automatic geotechnical rock mass characterization model able to estimate potential zones of over- or under-break of the remaining rock mass in underground blasting. By comparison of scanner profiles of the excavated sections with the blasthole positions, an Excavated Mean Distance (EMD) between the contour blastholes and the excavated profile has been obtained, which may be considered as damage measure. Considering blasting factors as constant, the model combines the rotary, percussive, hydraulic flushing and the rate of advance of the drilling, and the confinement of the rock mass by depth, to detect zones with different rock properties. This provide an early information of the rock mass condition around the blastholes and the prediction of expected overbreak generated after blasting, being possible to design more efficient bastings, in which each borehole is filled with the right and necessary explosive charge. The analysis comprises data from 57 blasts (around 1700 contour blastholes) and more than 4000 excavated sections.

By Clara Godoy, J. A. Sanchidrian

In this paper, Machine Learning techniques have been used to combine data monitored from the drill rig with scanner profiles of the excavated sections to develop an automatic geotechnical rock mass characterization model able to estimate potential zones of over- or under-break of the remaining rock mass in underground blasting. By comparison of scanner profiles of the excavated sections with the blasthole positions, an Excavated Mean Distance (EMD) between the contour blastholes and the excavated profile has been obtained, which may be considered as damage measure.

Feb 1, 2020

By J. Kulas, J. Weaver, K. Hagley

An assessment of potential groundwater movement beneath the tailing impoundment at the Red Dog Mine was performed, and has indicated a unique aquifer situation within sub-permafrost groundwater at the site. The aquifer was shown to be isolated from both vertical recharge and a real discharge, and is characterized as a virtually no-flow system. The permafrost resulted in a deep aquifer with high tidal efficiency, meaning that variable surface loads are easily transmitted to the fluid. The tidal efficiency has been characterized through analysis of water level fluctuations that respond to earth tides, barometric pressure loads, and loading from the pond.

Jan 1, 2002

By Andrew Thomson, Peter Wright

"A section of a London Underground expanded segmental lined tunnel constructed in the 1970’s progressively deteriorated after 2001, with extensive radial joint spalling and mid-segment cracking. As part of the PPP contract Tube Lines Ltd and their partners carried out various analyses of the tunnel, including analysis of laser scans of the tunnel, geotechnical testing through the tunnel walls, geotechnical desk studies, real-time monitoring and even full-scale segment testing. This paper discusses the behaviour of the tunnel lining in this setting, the causes of failure and the lessons that can be learnt from this rare example of a tunnel which was progressively failing in service. It is finally noted that a replacement tunnel lining was installed during night-time possessions and completed in 2015. INTRODUCTION In 2003, Tube Lines Ltd. was established under a Public-Private Partnership (PPP) scheme to provide maintenance services and upgrade projects for London Underground (LU). The Deep Tube Tunnel Knowledge and Inspection Programme comprised the assessment of all tunnels, shafts and other underground structures. This included a number of lengths of tunnel constructed using segmental concrete linings. First used by LU in the 1960s, the savings both in cost and speed of construction led to concrete linings replacing cast iron for new tunnel construction in all but a few cases. During the initial scoping phase of this programme, inspections identified potential issues with the expanded concrete segmental linings on the Jubilee line. The inspections found a number of segments with surface spalling (Figure 1a), which did not appear on the post-construction defect records. These were generally relatively shallow, up to 40mm deep, spread over a wide area of segment. These were different to spalls caused by handling damage, which are typically localised at segment corners. Subsequent inspections over the following years identified an increasing number of segments with these types of spalls as well as an increased incidence of longitudinal mid-segment cracking (Figure 1b). The increasing occurrence of these defects was hypothesised to be caused by tensile stresses developing in the vicinity of the joint."

Jan 1, 2016

By Leigh Sharpe

Dunng the last 5 years a United Kingdom colliery has utilised a yielding-pillar configuration to extract a relatively thick coal seam at a depth of 640 m. As part of ongoing research into the siting of roadways adjacent to extracted longwall panels, seved field monitoring sites were established at differing locations to investigate roadway stability and yielding-pillar performance. Characteristic roadway deformation has been identified together with strata softening pathways which indicate the temporal increase in the height of softening into the roadway roof. In the assessment of such a complex problem numerical modelling, using FLAC, has been shown to contribute vital additional information, and provide further insights into the mechanisms controlling strata behaviour.

Jan 1, 1998

By K Smith

This paper presents an assessment of the Robertson (2010a) method within the CPTu inversion parameter framework of Been et al. (1987), using CPTu calibration chamber data presented by Jefferies and Been (2015) and in other literature to assess the validity of the method, with particular focus on applicability of the method to TSFs (i.e. its applicability to loose silts and silty sands). The assessment demonstrates that although the method estimates values of k consistent with calibration chamber data, the method estimates values of m that are generally 1.5 to 2 times greater than calibration chamber data. As a result of this, the method generally overestimates Ψ for values of Ψ less than 0, and underestimates Ψ for values of Ψ greater than 0. This may result in both overly conservative assessment of materials as potentially liquefiable and unconservative predictions of material behaviour for loose materials.

Jul 1, 2021

By Agrawal A, Joshi A

Mochia mine, in culmination of depillaring operations, fired India's largest underground pillar blast consuming 145 tonnes of explosive and yielding 0.55 million tonnes of ore in June 1994. To protect main mine structures (situated at a distance of 250 to 350 m from the blast site) from resultant ground vibrations, the charge per delay was restricted to 2300 kg. The post-blast observations revealed that no damage was caused to these structures. However, the damage assessment survey of the mine workings situated in close proximity revealed a general trend in consonance with the distance from the blast and found to be well correlated with peak particle velocity.

Jan 1, 1995

By T. Verdel, Y. Gunzburger

Rockfalls are major and essentially unpredictable sources of danger, particularly along transportation routes (roads and railways). Thus, the assessment of their probability of occurrence is a major challenge for risk management. From a qualitative perspective, it is known that rockfalls occur mainly during periods of rain, snowmelt, or freeze-thaw. Nevertheless, from a quantitative perspective, these generally assumed correlations between rockfalls and their possible meteorological triggering events are often difficult to identify because i) rockfalls are too rare for the use of classical statistical analysis techniques and ii) all intensities of triggering factors do not have the same probability. In this study, we propose a new approach to investigate the correlation of rockfalls with rain, freezing periods, and strong temperature variations. This approach is tested on three French rockfall databases, the first of which exhibits an outstandingly high frequency of rockfalls (approximately 950 events over 11 years), whereas the other two databases are more typical (approximately 140 events over 11 years). These databases come from (1) the national highway RN1 on La Réunion Island, (2) a railway in the Bourgogne-Franche Comté region, and (3) a railway in the Auvergne region. Whereas a basic correlation analysis is only able to highlight an already obvious correlation in the case of the “rich” database, the newly suggested method appears to detect correlations even in the “poor” ones. Indeed, the use of this method confirms the positive correlation between rainfalls and rockfalls on La Réunion Island database. This method highlights a correlation between cumulative rainfalls and rockfalls in the Bourgogne region, and it detects a correlation between the daily minimum temperature and rockfalls in the Auvergne region. This new approach is easy to use and also serves to determine the conditional probability of rockfall function of a given meteorological factor. This approach will help to optimize risk management in the studied areas based on their meteorological conditions. Nevertheless, even if some rockfalls are correlated to meteorological factors, other seems to occur independently of these factors, which highlights the unpredictability of rockfall hazard.

Jan 1, 2015

By Yi-Hsuan Chen, Jürgen Brune, Candace S. J. Tsai, Alejandro Munoz, Connor Krause

This study highlights the significant presence of submicrometer- sized airborne particles in underground coal mines, especially around the belt conveyor drift areas. Using realtime instruments and gravimetric samplers, the assessment revealed that particle concentrations were notably higher in the belt entry compared to other locations, with a strong presence of submicrometer- and nanoparticle-sized dust. The study’s findings emphasize the importance of addressing small particle exposure, as these particles, composed of harmful substances like calcium, copper and iron, can pose serious health risks to miners. This research emphasizes the importance of improving air exposure estimation through more effective monitoring and characterization techniques to better understand and reduce workers’ exposure to hazardous airborne particles in the mining environments.

Apr 1, 2025

By A. W. Khair

This paper presents an analysis of fracture depth and intensity due to subsidence over the longwall panel. Sonic reflection techniques were utilized to determine fracture depth, and a variation of p-wave velocity was used as an indication of the fracture intensity. Instrumentation has been tested for consistency and accuracy first in the laboratory using small scale models, then applied in the field in two mine sites with different mining geometry and geologic conditions. A new sonic viewer was utilized for sonic velocity measurements. Regular hammering method was on acoustic source. The results were concurrent with monitored horizontal strain profiles and measured open fractures over the longwall panels.

Jan 1, 1989

By Stephan A. Jefferis, Adrian H. Bath

"This paper draws together some themes on the durability of barrier systems, and particularly cementitious systems. For contaminated land and water retaining structures, durability can be poorly addressed at all stages of a project, from specification, to barrier material selection, barrier design including toe-in and through to performance assessment in operation. Permeability (hydraulic conductivity) is a dynamic property which will vary over time as reaction processes propagate through a barrier. However, laboratory testing, when undertaken, tends to be focused on short term tests with aggressive chemicals so that the effects of longer-term processes such as carbonation and leaching by permeating water are missed. For water retaining structures, carbonation and leaching actually may be the most significant processes affecting barrier performance as the groundwater adjacent to many water bodies can be otherwise rather benign (as regards bentonite and cementitious systems). These and other reaction processes have been modelled in the arena of nuclear waste repositories and procedures are well recognised. However, such procedures have yet to be widely adopted for the assessment of other barrier systems.INTRODUCTIONOver the last few decades there has been an enormous amount of laboratory research on the durability of barrier materials or more specifically papers reporting the results of permeability tests. Unfortunately there is a much smaller literature on scaling test results to barrier dimensions in the field or to required design lives. Although in the geotechnical industry durability research has been largely laboratory based, in the nuclear industry where relevant timescales are multi-millennia rather than decades, research has been heavily underpinned by geochemical modelling. A significant purpose of this paper is to examine the tools that may be used to analyse the results of tests on barrier materials used in geotechnical engineering, for example, for water retaining structures and contaminated land and draw the attention of the construction industry to the potential of the modelling procedures developed for nuclear repository assessments. Modelling can help to identify underlying processes and so augment information from laboratory testing focused on changes of physical properties such as permeability and strength."

Jan 1, 2016

By Daan Maijer, Wade Marquardt, Robert MacKay, Steven Cockcroft, Farzaneh Farhang Mehr

"To comply with the new Corporate Average Fuel Economy (CAFE) standards, the automotive industry is aiming to reduce weight and increase the power and efficiency of small displacement engines through the application of forced induction technologies. As an example, there are now several 2.0 litre turbocharged engines in production, producing in excess of 240 hp. To meet the need for improved fatigue properties in the engine blocks used in these high-output engines, a new water-cooled chill technology is under exploration at UBC in partnership with General Motors and Nemak. A series of experimental techniques were used to assess the capability of the new chill to extract heat from an A319 casting in the vicinity of the main bearing bulk head. The results show that this method has the potential to achieve a reduction in secondary dendrite arm spacing thus meeting the new microstructural specifications for these engines.INTRODUCTION The automotive industry is working to meet the stricter efficiency requirements laid out within the CAFE (Corporate Average Fuel Economy) regulations (Bastani, 2012; Cole, 1995; Mackay, 2011; Miller, 2000), while at the same time not sacrificing performance. One approach is to increase the use of lightweight materials, which leads to a decrease in the overall vehicle weight and fuel consumption (Cole, 1995; Mackay, 2011; Miller, 2000). Other approaches include smaller displacement engines and gas-electric hybrid drivetrains. However, one trend that is becoming clear, is a greater emphasis on force induction gasoline engines. This allows for weight reduction to be achieved with smaller displacement engines without sacrificing performance. One consequence of this approach is that the engine block materials are subject to higher in-service thermal and mechanical cyclic loads (Cole, 1995; Miller, 2011; Heysler, 2001) The fatigue properties of an alloy are strongly affected by a number of the, as-cast, microstructure features including, Secondary Dendrite Arm Spacing (SDAS), porosity and eutectic lamella spacing (including intermetallic ß-Al5FeSi platelets) (Mackay, 2010a; Mackay, 2010b; Viet-Duc, 2015; Casellas, 2005). It is generally accepted they can act as fatigue initiation sites and that a reduction in their size will result in an improvement in fatigue performance. For a given alloy chemistry, one of the key parameters affecting the length scale of all three is cooling rate (Mackay, 2000)."

Jan 1, 2017

By M. A. Islam, H. Mischo, G. Barakos

Among the thirty-five declared critical raw materials (CRM) in the United States, there is no sustainable domestic production for the fourteen of them, while for some others domestic supply does not meet the national demand. Numerous potential critical raw material projects are in advanced exploration stages. However, the price uncertainties for many of these commodities put feasible future production into question and come into contrast with overly optimistic price forecasts published in all feasibility studies related to such exploration projects. Thus, in this work, a newly developed smart computational tool is used to evaluate the real perspectives of several CRM exploration projects implementing actual commodity prices, and to conduct reverse calculations in order to find the prices at which each project can be viable.

Mar 2, 2022

By Siân E. Boyd

Studies of benthic recolonization in the aftermath of marine aggregate dredging in the U.K. and elsewhere are limited and are largely confined to experimental circumstances. Investigations of the physical and biological status of licensed extraction sites in the U.K. at various times following cessation of commercial dredging are very limited, and so judgments as to the likely progress towards environmental restoration and the time-scales involved continue to be based on predictions rather than real data. This field-based research programme was commissioned to enhance the understanding of processes leading to physical and biological recovery of the seabed following dredging, thereby aiding the identification of practices to minimize environmental harm at licensed sites, and to promote rehabilitation on cessation. The outcome of survey work will have the notable benefit of allowing questions about the present status of locations hitherto subject to commercial exploitation to be answered directly, rather than by inference.

Jan 1, 2002

By S. E. Boyd

Studies of benthic recolonization following the cessation of dredging in U.K. waters and elsewhere are limited, and are largely confined to experimental circumstances. Investigations of the physical and biological status of licensed areas in the U.K. at various times following cessation of commercial dredging are very limited and so judgments as to the likely progress towards environmental restoration and the time-scales are often based on predictions rather than real data. This study was established to address this deficiency by assessing the status of seabed substrata and associated benthic fauna within and outside areas where dredging had ceased and to conduct follow up sampling to monitor progress towards full recolonization.

Jan 1, 2004

By James J. Anderson

In this talk I will report on an effort to reassess the risk of pile driving to juvenile salmonids migrating through Puget Sound. The study was motivated by the concern of the construction industry that provisions restricting pile driving during the spring migration is resulting in an unbalanced burden to the industry. In simple terms the industry wants to know if some construction can be conducted in the spring without harming the juvenile fish. Fisheries agencies have agreed to reconsider their regulations in the context of additional studies. So, in this talk I will present some thoughts on risk assessment in general and the results of our study to assess the impact of pile driving on Snohomish River juvenile pink and chum salmon that migrate through the Navy Homeport construction site at Everett. The research, which is being carried out by the Fisheries Research Institute at the University of Washington, was planned and is supported in a joint effort including: the Washington Department Fisheries, National Marine Fisheries Services, U.S. Fish and Wildlife Service; General, Manson, and Hurlen construction companies, the Department of Transportation and a number of Puget Sound ports authorities. I will first briefly discuss the early life history of the juvenile salmon the regulations are designed to protect Second, I will outline the legal criteria required for risk regulation and some specific thoughts on how a reassessment of pile driving risk might be approached. With this basis I will report on our research and how it can be applied to a new risk assessment.

Jan 1, 1990

By B Mohanty, D Zwaan

Systematic near-field vibration monitoring of stope blasts was carried out in a large, deep underground mine. A total of 31 production blasts were studied in order to investigate the effectiveness of existing blast designs. This involved the vertical retreat mining method, which requires drilling a raise bore or blasting a slot raise (typically 1.22 m in diameter) using large diameter boreholes (165 mm). The diagnostic technique employed multistation near-field monitoring of blasts with high-g (100 g) and high-frequency (>10 kHz) triaxial accelerometers. The amplitude of the vibrations is correlated with the strain energy transmitted from each explosive deck. The results showed that more than 30 per cent of the explosive decks contributed little energy to the rock breakage process in these blasts, and an equal number contributed only inadequately. These findings are indicative of serious blast malfunctions. The problems can be traced to inadequate deck blast design and possibly to drill hole deviation. The various causes for such malfunctions are discussed and remedial measures suggested.CITATION:Mohanty, B and Zwaan, D, 2015. Assessment of underground production blast designs and blasting performance, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 607–616 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By A. Tekin

In almost all branches of industry, machinery and equipment in operation cause vibration. Some sources of vibration affect only the operator’s hands, fingers, and arms, while others have adverse effects on the entire -body. Various types and numbers of machines are utilized in the mining sector, and operators with them are exposed to mechanical vibrations caused by the mining machinery they use. A field study was conducted to evaluate the vibration risks to the operators using mining machines in open pit mines. Vibration levels and whole-body vibration (WBV) measurements using various types brands, and models of construction equipment were evaluated in three different mines in the west of Turkey and compared to the the criteria specified in the EU 2002/44/EC directive and ISO 2631-1 (1997) standards. The results showed that operators using mining machinery for 8 hours were exposed to WBV levels below the EU limit (1.15 m/s2), while 44% of these operators were exposed to levels above the EU action limit (0.5 m/s2). Measurement data collected from the working environment and the recommended improvements that need to be made to reduce WBV exposures are presented.

May 2, 2022

By J. Peterson

A review of blast designs and improved blasting practices at the Ekati??Diamond Mine is presented along with the results of three blast-monitoring experiments. Blast monitoring was undertaken to investigate blast damage mechanisms in the mine's well jointed rock mass. Rock mass damage caused by production, pre-shear and wall control blasts was measured. Ekati??uses 270mm holes for production blasting, and 165mm holes loaded with a decoupled charge for pre-shearing. The production blasts are loaded with bulk emulsion / ANFO blends. The mine plan involves using 30m double benches. A 30m high pre-shear is drilled and blasted prior to the production blasting that is done with sequential 15m benches. This paper summarizes the monitoring equipment and data gathered to date.

May 1, 2001

By E. Gutierrez, P. Gillies

Asset Maintenance Readiness (AMR) provides a tailored reliability and maintenance strategy specific to operational needs. AMR delivers reliability and maintenance foundations for the plant and equipment before start-up. Having a dependable reliability and maintenance strategy before start-up is critical, particularly in those first weeks and months during ramp up to stable production. The Asset Maintenance Readiness is the integration of Reliability and Maintenance Engineering analysis/studies at the earliest stages of the new Production System concept and design and during the Capital Project CapEx phases; adding this analysis to the Capital Project CAPEX cost, will have an impact of 2% to 3% of total project cost, but will deliver a good compendium of benefits far from the AMR costs, and those results will be shown upon commissioning and during the life cycle of the plant.

Mar 2, 2022