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By CLYDE M. EYE

THE Sub-province of Benguet is in the North Central part of the Island of Luzon. Baguio, the capital, is situated on a piateau 5000 ft. above sea level, and is the main health resort of the Philippines. It is rapidly becoming the favorite resort for the China Coast as well, and has many miles of beautiful, curving drives with nearly every pine-covered knoll surmounted by a summer home. The United States Army has a recreation post here, known as Camp John Hay, with a well-equipped hospital, and there is a Country Club with a good golf course adjacent. The weather during the winter months and until late spring is ideal. The business center consists mainly of Chinese and Japanese stores, several hotels, and a large public market, in which are displayed all of the vegetables of the temperate zone, which are flown near Baguio, and many tropical and other products brought up from below. This district is reached from the Coastal Plain either by the old Benguet road built in 1904 by the United States Government, or by the Naguilian road, built some years later. The former is now a toll road, with a line of stages operating over it to and from Des Mortes in connection with the government-owned rail- road. Auto travel from Manila is also along this road, the trip from Manila to Baguio requiring about seven hours, following up the great valley north of Manila for nearly 150 miles to the lower end of the Benguet road, and thence to Baguio, 25 miles. This is an interesting, scenic trip; the road is especially famous for the zig zags where it climbs out of the canyon of the Bued River to the plateau. In the September number of the National Geographic Magazine, a fine aerial picture of this road, as well as of other interesting points in various parts of the Philippines, appears. Freight for the district is taken in mainly over the Naguilian road connecting with the railroad at Bauang. This route follows the ridges of the mountain slope with broad vistas and views of the coast.

Jan 1, 1930

By H. L. Teicliman, E. M. Sipprelle

ENACTMENT of Public Law 290 by the 78th Congress authorized the U. S. Department of the Interior, Bureau of Mines, to conduct an experimental program to develop the technology for obtaining oil from oil shale. In adopting and later extending this legislation, the Congress recognized the impending necessity of supplementing ground petroleum reserves with synthetic fuels. Under the provisions of this legislation, the Bureau of Mines, among other things, was charged with the responsibility of developing mining techniques, methods, and equipment for mining the oil shales of the Green River formation of Colorado, Utah, and Wyoming.

Jan 1, 1950

By M. Szumny, P. Mertuszka, K. Fuławka

Mining-induced seismicity is one of the adverse side effects of mining with the use of explosives at great depths. Disturbance of the primary stress state by the development of the network of excavations combined with the continuous generation of dynamic loads by the detonation of explosives in mining faces has a negative impact on the level of safety of crew and machines. To ensure the stability of excavations it is necessary to identify in detail the nature of the seismic hazard by means of continuous seismic measurements. Unfortunately, the technologies used so far are characterized by high costs of installation and further maintenance, which clearly limits the possibility of using a large number of stations in a small area. A breakthrough in this matter may be the technology of microelectromechanical systems, which is several times cheaper than standard solutions used in mining seismology. This technology, with the appropriate configuration of devices, can be successfully used to monitor dynamic phenomena generated by mining activities. As part of this study, the assumptions and configurations of a prototype 42-channel accelerometer network using MEMS technology have been presented. The network was installed in the Lubin underground copper mine in Poland in a seismically active area, where multi-face destress blasting are conducted regularly. As a result, 14 tri-axial accelerometers were installed in the immediate vicinity of the active mining front at a distance of about 1,000–4,000 ft (300–1,200 meters) from the closest faces. Highfrequency recordings are collected based on algorithms that trigger the system when the Peak Particle Acceleration set value is exceeded or on the basis of a manual external triggering device connected to the blasting machine. During the measurement period, several high-energy seismic tremors and several dozen of waveforms generated by blasting were recorded. The obtained results are the basis for assessing the effectiveness of the destressing measures and for the analysis of geomechanical risk based on periodic analysis of the velocity of seismic wave propagation

Jan 1, 2024

By J Light

Since 2019, the mine planning team at Olympic Dam has been establishing and maturing a shift from deterministic to probabilistic scheduling techniques. This paper outlines this journey undertaken by the mine planning team, key learnings from implementation and further work required to increase the level of planning maturity. Olympic Dam (OD) is a highly variable, polymetallic orebody with a vertically integrated value chain from operations to final product. The processing plant has a tight set of quality constraints which are managed through timing of stopes from varying parts of the orebody. Value is eroded for the operation when forecasted quality of the mine feed encounters disruptions from unplanned changes to the timing of stope starts. As production has moved from the historic Northern Mining Area into the more geologically complex Southern Mining Area, average stope size has reduced, resulting in increased mining fronts required to meet production targets. This has created a problem of increased schedule complexity and difficulties in identifying and communicating resource priorities within a large set of individual stope critical paths. The problem was approached by considering each stope as an individual project constructed by teams working across multiple projects at any one time. The operation could then be considered a multi-project environment with shared resources and enables the application of Critical Chain Project Management (CCPM) to the mine plan. Key to CCPM is the addition of time buffers to protect the critical path of a project form upstream or downstream processes. Implementation of time buffers protects the stope start date against compliance to plan variance. The monitoring of each time buffer consumption, as a proportion of total construction activities completed enables proactive prioritisation of resources. This resulted in an increase in the number of stopes starting in accordance with the mine plan, simplified communication of priorities to all levels of the operation, increased compliance to plan and a clear measure of schedule risk during planning routines.

Mar 29, 2023

By H Kurth

Oyu Tolgoi copper and gold mine in the southern Mongolia holds mineral resources that make it one of the largest known copper and gold deposits in the world. The project is operating an open pit mine on the near surface of Southern Oyu deposit and developing underground block-caving mine at the Hugo Dummet North where 80 per cent of total resources exists. Oyu Tolgoi (OT) commenced open pit mining in 2011 and implemented an industry standard blasthole sampling, and ordinary kriging grade control estimation with block-out process. Since 2017, grade control improvement projects have successfully completed that have led to the implementation of current, improved grade control system. Geological model is updated by blasthole logging on Leapfrog® and used for daily grade estimations. GC estimation is proceeded solely on Vulcan® by running Lava script and integrating with a relational database. Combination of block-out procedure produces GC model which is updated in Vulcan® and as well as in the database simultaneously. Switching to the integrated database eliminated many manual processes such as importing and exporting data and enabled access to the database anytime, anywhere and from any device. Thereby, these improvements allowed to increase an efficiency, create a comprehensive reconciliation system and reduce operational risks. We are looking forward to expanding applications of integrated grade control data stored in the database. This paper outlines how the grade control system was developed at OT’s open pit mine, and how it is integrated into the short range mine planning, mine reconciliation workflow and ultimately enabled development of various automated reporting systems.

Mar 22, 2022

By Filippo Maria Leoni, Wesley Schmutzler

"Deep Mixing Method (DMM) for the Rio Puerto Nuevo Project in San Juan was chosen by the Corps of Engineers to improve the soils adjacent to a 90 inch forced sewer main relocation and to improve the soils for the base of a new drainage channel. The project is located just east of San Juan and south of the Horizon Port. The soils to be improved consisted of fill, marine clay, organics (peat) and the foundation clay layer. A preconstruction soil investigation campaign was performed to assess soil properties and to retrieve samples of the different soil layers for the laboratory Bench Scale Testing program (BST). The BST was conducted using various binder contents and water/cement ratios in each of the soil types; the selection of the different combinations and dosages was based on past extensive experiences on similar materials. Following the laboratory program, a full scale Field Test (FT) was done installing several DMM elements to verify the results of the BST and fine tune the construction parameters. Each element consisted of two 5.5 feet diameter overlapping mixing augers installed simultaneously to a depth of approximately 60 feet using a SOILMEC SR-90 dual axis drilling rig. The FT construction and post-construction coring results showed significant differences between the lab study and the actual field conditions. This paper will highlight these differences and the importance of performing both pre-construction laboratory and field tests in order to ascertain the proper mixing parameters in the different soil layers.IntroductionThe Puerto Nuevo project consists of the stabilization of a major drainage channel using Deep Mixing Method (DMM) and the relocation of a 90 inch forced main sanitary sewer outfall. The first portion of this project was a 40 x 16 x 2,000 foot box culvert installed in 2004. In order for the drainage system to be completed and function properly, the 90 inch forced main needed to be lowered about 20 feet to allow for proper drainage.DMM was chosen by the US Army corps of Engineers to stabilize the drainage channel as well as improve the soil under the relocated sewer main. The overall layout of the project is shown in Figure 1. The DMM is arranged in different zones (A through E) with variable top and bottom design elevations as can be seen in the typical cross section for ZONE A and B as an example. (Figure 2) The total amount of soils to be treated by DMM is approximately 84,000 cubic yards up to a maximum depth of 57 feet from ground surface and an Area Replacement Ratio of 100%.The equipment used to perform the DMM is a Soilmec SR90 twin-shaft jet assisted deep mixing rig (Figure 3) coupled with a LODOS 30 grout plant and two Soilmec 7T-500J high pressure pumps."

Jan 1, 2015

By C J. Greet, J Kinal, C Hitchen

Following the successful completion of a marked ball test defining the potential wear benefits the high chrome alloys may offer against forged steel, as well as laboratory test work investigating changes in pulp chemistry and improvements to metallurgical performance, a plant trial was commissioned at NewcrestÆs Ridgeway concentrator. The paper briefly describes these results.Newcrest decided to convert their media charge by the top-up method. To monitor the trial a sampling protocol was put in place whereby the pulp chemistry was monitored before, during and after the purge. The metallurgical shift data was analysed using various statistical methods to determine if the metallurgical performance had improved with the change in grinding media. While the analysis indicated that the metallurgy had improved, not all of the benefits could be assigned to the change in grinding media alone. However, the combination of reduction in media wear and the increases in copper and gold recoveries suggested that it was economically viable to operate with high chrome grinding media.As with many trials of this nature the prevailing economic conditions are fluid and a decision was made to revert back to forged steel grinding media in an effort to reduce operating costs. It was further agreed that Magotteaux could monitor the pulp chemistry and metallurgical changes in this reverse trial to confirm the results observed in the earlier conversion to high chrome grinding media.CITATION:Greet, C J, Hitchen, C and Kinal, J, 2012. Conducting high chrome grinding media trials at NewcrestÆs Ridgeway Concentrator, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 56-64 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By E. Emami, J. Valencia, J. Sattarvand

The knowledge of the final location of a drillhole is critical in obtaining the expected blasting results. This paper proposes a new methodology to control the drilling accuracy in open-pit mines using aerial images and machine learning. Specifically, it investigates how support vector machines (SVM) and convolutional neural networks (CNN) are useful for automatically detecting blastholes over drone images captured in blasting patterns. Several datasets were obtained from different mines in Nevada (USA) and were used to train and test models. We then processed those images to create orthomosaic and digital elevation representations of the patterns. Thousands of patches were then extracted and augmented to develop SVM and CNN models. The results demonstrate that machine learning is useful for drillhole detection and, in this way, to control the drilling accuracy and use the explosive energy more efficiently.

Sep 1, 2021

By Martin N. Kelley

The Great Belt Link is a $3.5 billion fixed link across an 18 km (12 mile) wide body of water that separates the island of Zealand, on which Copenhagen is situated, and the main land mass of Denmark, Jutland, which is part of the European continent. The project consists of three main contracts. The first contract is an 8 km (5 mile) long, two-bore railway tunnel for the eastern half, the second contract is a 6.6 km (4 mile) combination railroad and highway bridge for the western half, and the third contract is a 6.7 km (4 mile) long high-level highway bridge for the eastern half. This paper will discuss the Eastern Railway Tunnel Project and the methods of construction that the joint venture consortium plans to use, along with its equipment selection. The ground conditions to be encountered begin with glacial tills, which are a mixture of clay, silt, sand, gravel, cobbles, and granitic boulders. The boulders can be up to 1-3 m (3-10 ft) in diameter. Underlying the till is a marl which is sometimes highly fractured with hydrostatic pressures of up to 8 bar. About 40% of the tunnel is in till and 40% in marl, with the remaining 20% being a mixed face of the two formations.

Jan 1, 1991

By W. E. Hale

An area of about 7,000 square miles within the eastern part of the Grenville Sub-province is underlain chiefly by granitic gneisses. There are, however, some exposures of mafic rocks which warrant further investigation, and some attractive structures, particularly basins, which deserve additional economic consideration. T HIS paper describes in a very general fashion the economic and geological features of an area of about 7,000 square miles on the north shore of the Gulf of St. Lawrence in the eastern part of the Grenville Sub-province (Figure 1). The scarcity of published geological data on this part of the Cana-dian Shield (DePuyjalon, 1899 and Longley, 1944) justifies the presentation of these tentative results. It should be appreciated, however, that the information which follows was acquired in a rapid reconnaissance designed specifically to out-line what might be interpreted as favourable geological environments for the occurrence of economic minerals, rather than to produce an authoritative analysis of the geological history of the region.

Jan 1, 1962

By Milton E. Jennings

On May 11, 1977, the SAMARCO 20-inch, 396-kilometer (246-mile) Pipeline was placed in service. This system represents the latest thinking in slurry pipeline design and is one of the main contributors to the viability of the SAMARCO Project. This paper presents the background, description and latest information on the system's operation. Special attention is given to the handling limitations of the slurry and to the unique hardware requirements.

Jan 1, 1978

By J. F. Barry

Newmont Mining Corporation and Barrick Goldstrike Mines, Inc. concluded an exchange of land and reserves in an agreement signed May 3, 1999.This exchange of assets allowed Newmont to develop the Deep Post underground mine from within Barrick’s Betze-Post open pit, thus reducing capital expenditures, lowering operating costs, and advancing the production schedule by nearly three years. Based on previous experience, Newmont is confident that the Deep Post underground mine can be successfully developed and operated within a large, active, open pit mine. The project also faces difficult geotechnical conditions including weak ground, scattered pockets of groundwater, and elevated rock temperatures.

Jan 1, 2000

By Lewis L. Oriard

The authors outline the development and application of blasting methods put into use 11 years ago at the Berkeley Open-Pit Mine, Butte, Montana. The blast design uses a very short delay (5 milliseconds) between detonation of explosives charges, a feature challenged several times in principle despite its success for Anaconda. Concern is expressed over the categorical rejection of very short delay blasting which can make the difference between success and failure of major mining operations. There is ample evidence to show that the method can be used successfully and not violate the concerns of the public.

Jan 1, 1980

By S. A. G. Poppen, J. Konopka

"Petro-Canada's project investigative and experimental underground work in the Galt coal seam at Kipp, Alberta included the construction of an emergency egress and ventilation raise from surface.The Galt coal seam is 206 m below the surface and covered by 8 m of shale, sandstone and clay beds of the Oldman Formation, 128 m of shale, bentonite beds and sandstone of the Bearpaw Formation, and 70 m of glacial till and basal gravel. Free water was encountered from sand lenses in the glacial till and the basal gravel.Excavation for the ventilation raise was a nominal 2 m diameter and it was lined with a welded, continuous, steel liner of 1.2 m 1.D.Excavation in the glacial till was carried out with a surface bucket drill rig combined with hand mining. Ground support in the glacial till consisted of liner plates and backfill grout. The Bearpaw and Oldman formations were excavated by employing standard raise boring techniques. The individual liner sections of the continuous steel liner were assembled on surface and the entire liner column was lowered into the raise by employing hydraulic lift climbers. The liner column was back-filled with concrete.IntroductionThe Lethbridge Coal Field comprises an area of approximately 1 165 square km in the vicinity of Lethbridge in southern Alberta. Pacific Petroleums Ltd. proposed in a Preliminary Disclosure in January 1979 ""to open an experimental mine prior to development of a producing underground mine with an initial rate of 540,000 tonnes per year"". A 2 900-hectare group of leases in the Kipp-Coalhurst area was selected as the primary target for the Kipp experimental mine. The scope of work for the experimental mine included the construction of an access shaft with production capabilities, the construction of a ventilation and emergency exit raise, drive-ages in coal to yield a bulk sample, gathering of geotechnical information and the testing of experimental mining methods."

Jan 1, 1983

By J. A. Procarione

Introduction Ventilation engineers have always felt somewhat uneasy when, in the normal course of their work, they are forced to consider the flow in any mine entry as "wholly rough." Under such conditions in pipes, friction factor is no longer a function of Reynolds' number. This assumption serves to simplify the problem and overcome an evident lack of information concerning the variability of K-factors. During the summer of 1985, a unique opportunity to investigate the reaction of friction factor to changing flow rates presented itself. A Utah coal mine was temporarily directing a substantial airflow through a single entry. By regulating the quantity, it would be possible to obtain a wide range of Reynolds' numbers in an entry composed of two distinct coal thicknesses. This paper describes the conducted study. The theory covering basic fluid flows in pipes that led to the questioning of constant K-factor is presented first. Experimental procedures are then described, including the use of a view camera in determining entry area and perimeter. Finally, a discussion of the observed variations in friction factor versus Reynolds' number is given. Changes of 34% and 45% in K-factor were seen in this study for the two entry heights. The implications of ignoring the relationship in this case and a call for an expanded research effort are also presented. Theory Since a gas is a fluid, the general principles of fluid mechanics are equally applicable to airflow in a mine entry as they are to the flow of water in a pipe. The Darcy equation is, therefore, equally applicable to pressure drop calculations in both situations. This famous formula was originally derived for use in circular cross sections and may be modified for any other shape by the use of hydraulic radius (defined as the area divided by the "wetted" perimeter). The Darcy equation relates the physical parameters of the pipe (diameter, length, and resistance to flow) and fluid velocity to the energy needed to create the flow. A study by Nikuradse (1933) brought to light the suspected dependency of the friction factor term in the Darcy equation upon Reynolds' number. By performing a large number of laboratory experiments, he established some basic concepts upon which other researchers built. Chief among these contributors was Colebrook (1939). Using commercial-grade pipe, he established an empirical relationship between Darcy's friction factor and Reynolds' number that is still in use today. If Colebrook's system of equations is plotted on log-log paper (as was done by Moody, 1944), the curves have some very distinct features. Of importance to the subject at hand is the relative response of friction factor to Reynolds' number at a given relative roughness. Simply stated, a pipe can appear to be either smooth or rough, depending on the flow conditions. As the Reynolds' number increases, the friction factor decreases at a decreasing rate until it becomes nearly a constant value. At this point, the flow is said to be "wholly rough." It is upon this condition that many traditional ventilation solution methods depend. For calculating pressure drops in a mine entry, Atkinson's equation is much more popular than the Darcy equation. Both of these formulas describe the same phenomenon and so have similar forms and functions. The K-factor in the Atkinson equation is equivalent to the Darcy friction factor and can be related by simply changing units, equating the pressure drops, and canceling like terms. A generalized form of this relationship is presented below as equation 1. K = yf/28,800g = [q]f/28,800 (1) where K is Atkinson's friction factor in kg/m3 (lb - min2/ft4), Y is the specific volume in Nt/m3 (lb per cu ft), p is the fluid density in kg/m3 (slugs per cu ft), g is the acceleration due to gravity (9.8 m/s2 or 32.2 fpsz), and f is Darcy's friction factor, which is unitless. The objective behind Eq. 1 is to show the strong correlation between K and f. Since these two quantities differ only by a constant (q]/28,000), the assumed independence of K-factor and Reynolds' number is suspect in light of the known response of f. Unfortunately, the formulation does not provide information concerning the actual relationship, as entry geometry likely plays a major role in the response curve. Only an indirect indication that such a relationship might exist is provided. Previous work on this subject was performed by Thomas Falkie (1958). The study involved a laboratory model composed of sections of straight, steel duct and a range of Reynolds' numbers from 15,610 to 137,200. Results from this work show a variation in friction factor with Reynolds' number in much the same way as it was found to vary in pipes. Over the range of velocities examined, a decrease of approximately 38% in K-factor was observed. This previous experience provides additional incentives to investigate the phenomenon under field conditions. Past model studies done at the University of Utah by Ozukurt (1945), Biron (1944), and Greenhalgh (1942) present similar evidence of this variability. More recently, Kharkar's (1974) study of coal mine friction factors contains similar indications that K-factor is not constant in all situations. Taken together, the data

Jan 1, 1988

The first grant of land rights in Australia was pursuant to the Aboriginal Land Rights (Northern Territory) Act 1976. That Act has been at the core of the dispute between land rights and miners' rights. The mining industry believes that the Act, in giving a right of veto to Aborigines with respect to exploration and mining on Aboriginal land, has been responsible for a stagnation in exploration amd mining activity in the Northern Territory. In February 1985 the Commonwealth Government released for public comment its preferred model for national land rights legislation. The model has been opposed by the mining industry because it believes, first, that land rights is a matter which should be left to the States and, secondly, that the detailed mechanisms contained in the model constrain the industry in the manner of the Northern Territory legislation. Aboriginal leaders have opposed the model because it does not, in their view, measure up to undertakings given by the Commonwealth Government and, in addition, it provides for amendments to the Northern Territory legislation which are likely to result in the loss of the Aboriginal veto right. Are land rights and miner's rights compatible? The answer is yes provided all parties, including Governments, are prepared to talk and compromise and Governments recognise that the grant of land rights and any control by the Aboriginal people of exploration and mining on their land is not a substitute for raising the living standards of Aborigines as a significant group of disadvantaged Australians.

Jan 1, 1986

By Robert B. Scott

The Dents Run Demonstration Project near Morgantown, West Virginia, was a cooperative venture involving the U.S. Environmental Protection Agency (EPA), the Water Resources Division (WRD)(1) of the West Virginia Department of Natural Resources (DNR), and the Christopher Division of the Consolidation Coal Company (CONSOL). The object of this project was to demonstrate pollution control methods and to clean up a 37.8 sq km (14.6 sq mi) watershed severely polluted by coal mine drainage. A study entitled, "Water Infiltration Control to Achieve Mine Water Pollution Control" (EPA-R-2-73-142),(2) was conducted by the Cyrus Wm. Rico Division of NUS Corporation for the grantee to determine the feasibility of utilizing remedial techniques to improve the Dents Run water¬shed. This study showed that the Dents Run watershed was discharging as much as 6,870 kg/day (15,100 lb/day) of acid; 1620 kg/day (3,560 lb/day) of iron 17,250 kg/day (38,000 lb/day) of sulfates; and 29,500 kg/day (64,900 lb/day) of total dissolved solids into the Monongahela River near Morgantown, West Virginia. This pollution was caused by the combination of borehole pump discharges from active underground mines, runoff from abandoned strip mines, and runoff from refuse dumps.

Jan 1, 1977

By E. H. Christiansen

The most valuable gem- quality red beryl comes from the Wah Wah Mountains of south-western Utah (Fig. 1). Red beryl occurs as a secondary mineral in topaz rhyolite. Marketable crystals from the Wah Wah Mountains have been produced from the Violet Mine, operated on a limited scale since 1976 under the ownership of the Harris family of Delta, UT. From 1989 to 1995, production from the mine amounted to more than $3 million with an inventory of several million dollars of unsold gems (Harris, 1995). In 1994, Kennecott Exploration leased the mine and surrounding claims to determine reserves and feasibility of gem recovery. Mining and exploration activity are continuing. Previous work on red beryl has dealt mainly with crystallographic, chemical and optical properties of the crystals (Shigley and Foord, 1984) with only general descriptions of the geology (Ream, 1979). However, the conditions needed for formation of red beryl have not been well constrained. It is generally proposed that beryl originates by precipitation in fractures and vugs from high-temperature gases as they are released from slowly cooled rhyolite lava. Dozens of topaz rhyolite flows and domes, similar in composition to the beryl-bearing flow in the Wah Wah Mountains, occur across the western United States (Christiansen et al., 1986). All of these flows devitrified to form vapor-phase topaz and locally other vapor-phase minerals such as bixbyite, garnet, hematite, pseudo-broo- kite and fluorite. But the occurrence of beryl is rare. Even within the rhyolite flow that hosts the red beryl, the productive open pits comprise only a small fraction of the surface area of the flow. Apparently, the conditions that favor the formation of red beryl are rarely achieved. Geologic setting The rhyolite flow that hosts the red beryl deposit lies along the eastern flank of the Wah Wah Mountains (Fig. 1). Prevolcanic rocks consist of Proterozoic, Paleozoic and Mesozoic sedimentary rocks that were folded and thrust to the east during the Sevier orogeny. Cenozoic volcanism began about 34 Ma. It consisted mostly of large volume dacitic ash flows and lesser volumes of low- silica rhyolite and andesitic lava flows. Beginning about 23 Ma, the style and composition of volcanism changed to smaller-volume, ash-flow and dome-forming eruptions of high-silica rhyolite and trachyandesitic lava. These rocks form the Blawn Formation of which the beryl-bearing rhyolite is one member (Best et al., 1987). Abbott et al. (1983) reported a K-Ar age of 22.1 + 0.8 Ma for this flow. It is probably the oldest topaz rhyolite flow in the Wah Wah Mountains. A subsequent episode (12 to 13 Ma) of bimodal magmatism produced the Steamboat Mountain Formation. The rhyolitic part of that is locally topaz-bearing. Displacement on the late Cenozoic extensional faults that formed the north-trending mountain ranges began about 22 Ma. Geology of the Violet Mine The rhyolite that hosts the red beryl deposit is part of a flowldome complex that overlies nonwelded tuff of cogenetic origin. This rhyolite is exposed over an area of about 9 km2 (3.5 sq miles) (Fig. 1). An unknown additional portion of the rhyolite is concealed beneath younger mafic lavas and sediments.

Jan 1, 1997

By Kishore Kumar B., Eswaran Prasad C R, Srini Naik B., Ramakrishna Raju N

The authors through this paper intend to introduce the non-vibro technique of ground improvement by stone column, being used for the first time in India under the Western Dedicated freight Corridor in Mumbai area. New 2x25 KV double line dedicated freight corridor tracks, capable of carrying 32.5-ton axle load are proposed to be built on this stretch. Non-Vibro Displacement Stone Columns of 900 mm diameter were installed to improve the safe bearing capacity of the soft ground to take the loading of Dedicated Freight Corridor Railway embankment. Vertical footing load tests on single and three column groups were conducted to assess the improvement in the sub-surface condition after installation of stone columns. This paper describes load tests conducted on stone columns and analysis of the obtained results. The observed load settlement behaviour of the improved ground has also been presented. Behaviour of single and group of stone columns have been compared and criteria adopted for arriving at desired factor of safety based on the settlement observed, has also been discussed.

Nov 1, 2022

By B. H. Kim, P. Zhang, M. A. Van Dyke, D. Su, H. Dougherty

The National Institute for Occupational Safety and Health (NIOSH) has been evaluating longwall mining-induced strata fractures and their impacts on casing stability of Marcellus shale gas wells located in longwall pillars. To understand the extent of overburden fractures after longwall mining, NIOSH researchers drilled a postmining corehole into the fractured strata above the Pittsburgh coal seam longwall gob. Knowing the extent of the fracture zone height will help gas operators minimize the hazards of drilling into longwall gobs. The core was retrieved from the surface down to the top of the gob void. Various fractures were encountered varying from 35 to 64 degrees, depending on lithologic type and relative closeness to the gob. The longwall panel dimension was 457 m wide and 3657 m long, in which the total fracture zone height was found to be at 141 m and the hydraulic connected fracture zone at 87.7 m above the top of the Pittsburgh seam. In addition to core drilling through the gob, FLAC3D modeling was also used to simulate the formation of fracture zone and the orientations of longwall-induced fractures. This study provides much-needed evidence on the fracture zone of Pittsburgh seam longwall gobs to help gas operators avoid potential hazards associated with drilling through highly fractured zones

Mar 2, 2022