Search Documents

By A Weston

Northparkes Mines is a joint venture between Rio Tinto and the Sumitomo group and is operated by Rio Tinto to produce copper concentrate from ore sourced from open cut and underground. Underground ore is mined with an owner operator workforce using the block cave method from the E26 deposit, with the first lift of the cave now completed. Development of the Lift 2 block cave commenced in March 2001 using a contract workforce. The Lift 2 Project required the mining of 14 700 m of decline and lateral development to establish a new mining horizon at the 9450 level and to develop two new conveyor declines. Also included in the scope was the excavation of a Crusher chamber to house the jaw-gyratory crusher. This paper describes the excavation of the hydroset chamber and orepass that sit immediately underneath the Lift 2 Crusher chamber. It includes risk assessment, planning, development of method statements and standard operating procedures, through to the excavation of the orepass and the installation of ground support in seismically active ground. There was a major ground failure in the backs of the conveyor feeder chamber during its excavation, which affected the excavation of the orepass due to its proximity to the breakthrough site.

Jan 1, 2005

By Turco E, Pelizza S, Castellani F, Stanganelli V

Excavation are in progress for the building of tunnels of the waterworks in West Campania (Naples). The works afferent to part II envisage tunnelling through a miocenic clay formation over consolidated by two tunnels whose sections are respectively 50 and 10m2. Tunnel blasting is carried out by mechanical means. An excavator is used in the big tunnel, whereas in the small tunnel a roadheader machine is used for a short tract and a mechanized shield is used over a long stretch. The tunnel feature complex problems regarding stability. This is particularly so for the big tunnel whose face appears unstable. For this reason the clay on the face is sistematically bolted by means of 3-metre and 12-metre bolts. This prevent the use of a TBM for tunnel Excavation.

Jan 1, 1987

By Roy H. Patten

When driving a shallow soft ground bore, the appearance of surface craters along the tunnel alinement indicates trouble, particularly when a major highway is intersected. During the excavation of a 3.7 m diam tunnel in Seattle, Washington a chemical grouting program was implemented to stabilize soil conditions sufficiently to allow advancement of the mole without loss of ground. Unanticipated mixed face conditions consisting of saturated running sand and some boulder pockets bedded on top of dense glacial till created excavation difficulties. A discussion of problems and corrective measures is presented.

Jan 1, 1987

By James P. Chivilo, Gregory R. Meeder, Scott J. DiFiore, Matthew H. Johnson

New construction in metropolitan areas has direct impacts on immediate neighbors and abutters. While noise and dust are generally nuisance concerns, demolition, vibrations, excavation, and dewatering can cause structural damage to adjacent structures. Different cities, states, or jurisdictions have different regulations that dictate requirements, roles, or responsibilities for varying parties during construction. The authors will introduce and discuss risks of new construction adjacent to existing structures, and the legal framework in Illinois which requires the owner of the new construction project to provide adequate protections for adjacent existing structures. The authors, who are engineers and attorneys, will discuss technical and legal concerns, and will highlight the importance of early and frequent communication among project participants to manage risks, despite whether or not any local regulations exist to drive the process. RISKS IN ADJACENT CONSTRUCTION New construction in metropolitan areas inherently involves some combination of noise, dust, ground-borne vibrations, earth excavation, and subgrade dewatering. These issues have potential to directly and adversely affect abutters and their property. Noise and dust can be nuisance concerns, while vibrations, excavation, and dewatering can result in damage to abutters’ structures. Noise and dust are unlikely to lead to physical damage to abutters’ property, and can be controlled with limited work hours and good housekeeping practices. Vibrations and excavations, however, if not well understood, planned for, and mitigated, can result in serious damage to abutters’ structures. In turn, this damage introduces additional and often significant costs and schedule delays.

Jan 1, 2019

By J. Xiao, Y. Jiang, Y. Tanabashi, Z. Song

Modelling the effect of blasting-caused damage, anisotropy of rock masses and excavation sequence on deformational behaviour and stability of large-scale underground caverns is important in the design and information-oriented construction of the pumped storage power plant. A powerful three-dimensional numerical method that can be applied for that purpose is presented in this paper. Damaged range caused by blasting and mechanical properties of rock masses near to the walls of caverns are determined by using the back analysis approach in which three lines of the measurement results during the arch part excavation process were used to verified the simulations. Finally, applying the improved model and properties of rocks, the cavern stability and reinforcement effect of the preliminarily designed support system are also estimated for the safety in the bench excavation process. La création de modèles des effets relatifs aux dommages résultant des explosions, à l’anisotropie des masses rocheuses et à la séquence d’excavation quant au comportement à la déformation et à la stabilité des cavernes souterraines de grandes dimensions est une étape importante dans l’étude et la construction sur ordinateur de centrales hydrauliques à accumulation par pompage. Cet article traite d’une méthode numérique tri-dimensionnelle puissante applicable à cet effet. La gravité des dommages résultant des explosions et les propriétés mécaniques des roches à proximité des parois de la caverne sont déterminées par une analyse du fond dans laquelle les simulations sont vérifiées à l’aide de trois lignes de résultats de mesures prises durant le processus d’excavation de la partie arche. Finalement, la stabilité de la caverne et les effets du renforcement du système de support préalablement conçu sont estimés par application du modèle amélioré et des propriétés de la roche, pour application à la sécurité durant le processus d’excavation en gradins. Nachahmung der Wirkungen von durch Explosionen hervorgerufenen Schäden, Anisotropie der Gesteinsmassen und der Ausschachtungssequenz auf das Verformungsverhalten und die Stabilität großräumiger Untergrundhöhlen ist für das Design und den informationsorientierten Bau von Pumpenkraftwerken wichtig. Entsprechend der Vorgaben in dieser Arbeit kann ein leistungsfähiges, dreidimensionales numerisches Verfahren für diesen Zweck eingesetzt werden. Der durch Explosionen und die mechanischen Eigenschaften des Gesteins bedingte Schadensumfang im Bereich der Höhlenwände kann mit Hilfe eines retroversen Analyseansatzes bestimmt werden, bei dem die drei bei der Ausschachtung resultierenden Messlinien dazu genutzt wurden, die Simulationen zu bestätigen. Abschließend wurde außerdem durch Einsatz verbesserter Modelle und Gesteinseigenschaften die Auswirkungen vorläufig entworfener Unterstützungssystem auf die Höhlenstabilität und Verstärkungswirkungen hinsichtlich der Sicherheit bei Böschungsausschachtung abgeschätzt.

Jan 1, 2003

By David S. Yang, Osamu Taki

The innovative Soil-Cement Mixing Wall Technique, developed independently in Japan, consists of mixing in-place soils with cement grout using multi-axis augers and mixing paddles to construct overlapping soil-cement columns. The applications of overlapped soil-cement columns include cutoff walls for groundwater control and structural diaphragm walls for excavation support. The special features of this technique include water tightness, versatile strength design, and efficient installation in subsurface materials varying from clayey soils to cobbles or soft rocks. Through the introduction of two recent subway projects in Japan, this paper presents the design parameters, construction procedure, quality control and performance of soil-cement wall for excavation support and groundwater control.

Jan 1, 1989

By Tony Mazzo

It has often been said by consulting engineers that foundation contractors are in the business of taking risks. One would agree that the mere fact a foundation project can be budgeted, planned, engineered and executed solely on the reliability of eight test borings made at a proposed site having an area of approximately 19,000 square feet, is a risky proposition, in and of itself. Now imagine that this site is actually one half of a city block located in an urban setting in an old, congested, historical neighborhood, surrounded by narrow city streets and historic landmark buildings. And suppose that the required depth of excavation for the construction of the new building on this site is approximately 35 feet and the natural groundwater table is at a depth below existing grade of only 25 feet. Given the difficult site conditions outlined above, one could certainly add the words "challenging" and "complicated" to the inherent word "risky" when describing the construction techniques involved to undertake a foundation project of this magnitude. This case study will discuss in detail how the excavation, sheeting, dewatering and underpinning work was accomplished as well as the problems overcome along the way.

Jan 1, 2003

By Harald Ludwig

In 2002, excavation support work commenced on the Capitol Visitor Center project located adjacent to the nation?s Capitol building in Washington, D.C. The outlying work (Slurry Wall Work at Main Site is not discussed) consisted of providing excavation support for a new truck tunnel approximately 1900 feet long up to 50 feet deep as well as support for the new underground auditorium and Library of Congress tunnel. The excavation support consisted of a combination of conventional drilled in soldier beams, lagging, tiebacks and braces; intricate underpinning inside the existing Capitol building; support of an existing Russell Tunnel; soil nailing and tiebacks underneath the existing Russell Tunnel; two temporary bridges; and a deep soil mixed wall with lateral support provided by braces. As part of an on-going research program, some of these braces were instrumented with strain gauges. The deep soil mixed wall was approximately 300 feet long and 65 feet deep on either side of the truck tunnel. Approximately 34,000 sf of deep soil mixed wall, 90,000 sf of conventional excavation support, 200 braces, and 320 tiebacks were installed. This paper describes the large scope and breadth of the project that required a variety of excavation support techniques. A few of the challenges in designing and installing the support of excavation are discussed. This paper also presents the results of the instrumentation program conducted on the deep soil mixed wall, which stood open for more than a year.

Jan 1, 2006

By D. Barber, A. D. Miller, P. A. Bray

The project was to develop an area within the existing West County Wastewater Treatment Plant which would enable the construction of a new Raw Wastewater Pump Station (RWPS) with a footprint of approximately 85 feet by 190 feet and a foundation depth of about 82 feet below grade and a new Short- Term Detention Basin (STDB) with a footprint of about 80 feet by 130 feet and a foundation depth that varied from approximately 3 to 24 feet below grade.. The excavation support system had to be designed to withstand both normal and the 100-year flood elevations. A Reinforced Soil-Cement Wall (RSW)was chosen to provide a hydraulic barrier which consisted of a single row of soil-cement elements installed along the perimeter of the area to be excavated. Steel wide flange beams were installed on 4 foot centers to support construction loads and be resistant to the lateral forces of the soil and hydrostatic pressures. The RSW was installed to a maximum depth of 104.5ft using a triple-auger drill rig with mixing paddles with a 2ft key into weathered shale providing a cutoff wall consisting of 53,150 square foot of treated soil. The project was to provide the initial design of the excavation support for the pumping station excavation support system and groundwater cutoff. There was 534 linear foot of soil-cement-bentonite wall installed and 106 - 80 foot long W21 x 121 wide flange beams installed on four foot centers into the alignment of the wall. Each element was drilled down into the weathered shale to obtain groundwater cutoff. Derek R. Guthrie Water Quality Treatment Center Pumping Package is the site for a new pumping station that will service Louisville, Kentucky residents. After unplanned long term exposure into the winter, the effects of freeze thaw cycles were evident.

Jan 1, 2017

By A Garg

Squeezing can occur both in hard rock and in jointed rock mass as a result of over stressing. It is related to time dependent shearing, ie shear creep and is associated with the volumetric expansion (dilation) and radial inward displacement of the tunnel surface. While planning a tunnel in hard rock under a high cover of the order of 2 km it is desirable to identify the potential squeezing ground conditions and to select appropriate excavation technique and the support measures. There are several solutions to counter balance the squeezing ground viz over excavation of tunnel profile, assessing appropriate excavation technique, provision of a ductile primary support and time for providing tunnel lining. Low drivage rates and high cost due to support failures requiring rectification arising out of poor anticipation of tunnel closures and support pressures are major problems associated with tunnelling under squeezing ground conditions. Under squeezing ground conditions, the deformation will be gradual, therefore, in order to absorb deformations yielding supports are quite useful as primary support which provide a reliable low initial support pressure and permit uniform stress relief of the surrounding rock along with preventing rock from ravelling. The paper discusses the various factors which influence the selection of appropriate excavation technique and support measures in hard rock under squeezing ground conditions.

Jan 1, 1999

By Andhra Pradesh, Nagarajkumar B. V

As a part of Mumbai City Mega Drinking Water Project at Amar Mahal Tunnel-1 Ghatkopar East Mumbai, drinking water tunnels were proposed by MCGM from Amar Mahal to Trombay reservoirs, Amar Mahal to Wadala and further up to Parel. The pipeline has to be underground and laid at a depth of 5.5m. The initial proposal was to provide sheet piling to enable the safe excavation and installation of underground pipeline. However, installation of sheetpiles was practically not feasible due to the existing soil strata for driving the sheet piles. Hence, it was proposed to install micropiles instead of sheet piles. In this paper we discuss about the purpose, basic design, detailed design approaches and actual work implementation of micro pile with temporary struts for shoring protection works in this project.

Sep 1, 2022

By R. S. Sinha

A properly designed pre- and post-grouting program aided with coherent construction sequence and adoption of flexible design approach provide a practical combination to solve excavation problems in a hostile rock environment: intensely fractured and sheared. The Pacheco Pumping Plant demonstrates the utility of an engineered grouting program.

Jan 1, 1984

By Hugo Meggitt, Damian R. Siebert, Wystan Carswell

Excavation-induced ground movements are a critical component in the design and construction of deep excavations in urban settings due to the potential adverse effects on adjacent structures and infrastructure. Ground movements are influenced by soil stratigraphy, soil properties, adjacent structures, and construction means and methods. The use of empirical relationships, computer models, and reliance on experience with similar excavations in similar soil conditions often provides a basis for predicting excavation-induced ground movements. In this paper, data from 21 deep excavations approximately 20 ft to 75 ft deep supported by concrete diaphragm “slurry” walls in the Greater Boston area are compared to published literature, considering how different foundation systems (e.g. shallow foundations, caissons, and piles) of abutting structures have been affected by adjacent excavations. The influence of construction method (conventional vs. top-down) on adjacent foundation movements indicate that top-down construction typically results in smaller foundation movements. INTRODUCTION Estimation of ground movements due to excavation is a challenging endeavor, even with complex three- dimensional finite element modeling and high-order constitutive models that are increasingly available in modern engineering practice. Aside from the expense of the soil exploration and testing used to inform these higher-order models, the challenges of modeling past stress history, adjacent structures, and the groundwater conditions during excavation require not only large investments of time during design but also validation from past experience (to avoid a “garbage in, garbage out” paradigm). While site conditions such as soil stratigraphy, soil properties, groundwater conditions, and as-built conditions of adjacent structures can be obtained, measured, and estimated, the effects that means and methods of construction have on ground movements are difficult to quantify. During early phase design, assessments of predicted ground movement are unable to account for all aspects of project construction, nor is it cost-efficient to fully design an excavation while project parameters such as site size and excavation depth are under consideration by the design team. While construction is in progress, benchmarking support of excavation performance and associated ground movements in the context of successfully completed projects allows for a more nuanced view of system performance and provides the opportunity for more informed decision-making (if required) as construction proceeds. For these reasons, the use of empirical relationships and the collection of historical support of excavation performance holds high value for the practicing geotechnical engineer at all phases of the project.

Jan 1, 2019

The excavator selection process is quite complex due to the large number of influencing factors, many of these are variable and difficult to accurately define. The majority of mining companies prepare a tender of general specifications and suppliers will then match a product to those specifications. The mining company will then evaluate the tenders on the basis of the best available deal. In this paper, the importance of open pit excavator selection in terms of its impact on operating costs is analysed and discussed. A rigorous process for selection is then outlined.

Jan 1, 2003

By H. Rumfelt

Surface excavators for mining coal and such non- metallic minerals as quarry stone, gypsum, phosphate and the like have advanced tremendously in the last 50 years, and their advancement has paralleled that of excavators used in the construction industry during the same period. Up to a certain stage, the construction industry led the way with this development and even pioneered in how the equipment was used. Afterwards, however, new mining machinery and related operating techniques progressed along a different path than their construction counterparts because of the different demands of the two industries. The word "stage" as used above quite generally connotes a transition period, possibly of several years' duration, during which mining development followed the construction industry. Later, mining branched out and responded to its own needs. Most readers are familiar with the events which led to the development of the power shovel. The first dredge was recorded as having been used in England in the latter 1700's and was no doubt developed along the lines of some notes written in the late 1400's by Leonardo da Vinci.

Jan 1, 1971

By Gustavo De la Torre Guzmán

En planta concentradora – Cerro lindo en su afán de consolidarse como una operación de categoría internacional, mantiene el enfoque de excelencia operacional gestionando de forma sistemática seguridad, salud ocupacional, medio ambiente, costos, productividad, calidad y confiabilidad además de nuestro proceso productivo. Para lograr el desempeño de categoría mundial y ser catalogados como tal, implica también usar la capacidad total del área (procesos, tecnología y talento humano) para implementar estrategias de optimización que garanticen la efectividad de las operaciones, para el éxito del proceso.

Sep 1, 2017

By Gustavo De la Torre

Más allá de contar con las certificaciones ISO 9001, ISO 14001, Y OHSAS 18001, la planta concentradora de Cerro Lindo busca ser catalogada como un desempeño de categoría mundial, lo que implica usar la capacidad total del área (procesos, tecnología y talento humano) basado en un equipo de alta performance-EAR, y gestionar de forma sistemática seguridad, salud ocupacional, medio ambiente, costos, productividad, calidad y confiabilidad, además del proceso productivo. En el presente artículo se analiza información recopilada durante la fase de crecimiento, se presentan diferentes etapas en desarrollo y se describen los estudios realizados en la planta de beneficio, a nivel técnico y de gestión, con óptimos resultados de producción, eficiencia e indicadores metalúrgicos.

Apr 30, 2018

By Hubert Gamarra

El presente trabajo señala el proyecto de evaluación y recuperación del molibdeno en la mina Chabuca Sur, perteneciente a BHP Tintaya. El proyecto sigue la metodología de Excelencia operacional (EO) o metodología de mejora continua utilizada en BHP Tintaya S.A y se realiza a corto plazo, con la finalidad de incorporarla bajo un costo mínimo en el stock. Asimismo, se determina una asociación del S2Mo como un pulso tardío de mineralización sin cobre en la zona de alteración argílica de los diques monzoníticos y en el endoskarn.

Sep 13, 2001

By Ifeanyichukwu Nweke

"Aluminium rolling processing from ingots to cold rolled coils comes with a lot of challenges especially in controlling defective products in casting, hot mill and cold mill operations. Hence this study focused on reducing defects at mills and cast-house using six sigma approaches. The use of six sigma approach will help the production experts to determine the gap between its operation and world class process. Practical data from First Aluminium Rolling mills were presented and analysed and mini improvement projects were proposed based on organisation need to achieve excellence. This study encourages aluminium alloy industries to pursue process improvement projects on the basis of analysis on data obtained from their shop floor, hence ensuring that through this, recovery is improved and cost of poor quality is reduced.INTRODUCTION Engineer Bill Smith while working at Motorola in 1986 introduced a new concept in which a set of techniques and tools are used for process improvement by controlling variations (defects). These tools and techniques are explained by an acronym DMAIC. D DEFINE the problem M MEASURE the variables in the problem A ANALYSE the variables of the problem I IMPLEMENT and verify the solution to the problem C CONTROL the solution to sustain it Most times in six-sigma approach, variations in the process that results in defects and customers’ dissatisfaction are targeted at 3.4 defects per million opportunities. There are numerous methods six sigma application use to achieve quality results and innovative strategies. Improving the quality of process through these methods helps identify and reduce variations which paves way for organisational excellence. In this study, it is encouraged to use six sigma techniques to improve aluminium rolling operations and other aluminium processing activities, the benefits of such improvement concept include: • Satisfy the voice of the customer (VOC) • Minimise costs • Maximise Profits • Build Good Team • Implement Profitable Project"

Jan 1, 2018

The theme of the conference is "excellence", an epithet of special significance in tertiary education. It appears in the mission statements, goals and plans to achieve them of most, and quite possibly all, tertiary institutions in Australia. In the context of excellence, this paper examines the current statue of professional education in the principal mining industry related discipline of Mining Engineering. It furthermore, identifies and discusses a number of special problems in mining education that the tertiary sector has long endured. Some of these problems are becoming acute, and solutions will have to be found soon in order for the industry to be assured of the supply of well motivated and appropriately qualified young engineers and scientists necessary to achieve and maintain the excellent to which it aspires.

Jan 1, 1989