Rock Support In Mining And Underground Construction Pdf
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A vertical opening is usually called a shaft. Tunnels have many uses: for mining ores, for transportation—including road vehicles, trains, subways, and canals—and for conducting water and sewage. Underground chambers, often associated with a complex of connecting tunnels and shafts, increasingly are being used for such things as underground hydroelectric-power plants, ore-processing plants, pumping stations, vehicle parking, storage of oil and water, water-treatment plants, warehouses, and light manufacturing; also command centres and other special military needs.
True tunnels and chambers are excavated from the inside—with the overlying material left in place—and then lined as necessary to support the adjacent ground. A hillside tunnel entrance is called a portal ; tunnels may also be started from the bottom of a vertical shaft or from the end of a horizontal tunnel driven principally for construction access and called an adit.
So-called cut-and-cover tunnels more correctly called conduits are built by excavating from the surface, constructing the structure, and then covering with backfill. Tunnels underwater are now commonly built by the use of an immersed tube : long, prefabricated tube sections are floated to the site, sunk in a prepared trench, and covered with backfill. For all underground work, difficulties increase with the size of the opening and are greatly dependent upon weaknesses of the natural ground and the extent of the water inflow.
It is probable that the first tunneling was done by prehistoric people seeking to enlarge their caves. All major ancient civilizations developed tunneling methods. In Babylonia , tunnels were used extensively for irrigation; and a brick-lined pedestrian passage some 3, feet metres long was built about to bc under the Euphrates River to connect the royal palace with the temple.
Construction was accomplished by diverting the river during the dry season. The Egyptians developed techniques for cutting soft rocks with copper saws and hollow reed drills, both surrounded by an abrasive, a technique probably used first for quarrying stone blocks and later in excavating temple rooms inside rock cliffs.
Even more elaborate temples were later excavated within solid rock in Ethiopia and India. The Greeks and Romans both made extensive use of tunnels: to reclaim marshes by drainage and for water aqueducts, such as the 6th-century- bc Greek water tunnel on the isle of Samos driven some 3, feet through limestone with a cross section about 6 feet square.
Perhaps the largest tunnel in ancient times was a 4,foot-long, foot-wide, foot-high road tunnel the Pausilippo between Naples and Pozzuoli, executed in 36 bc. By that time surveying methods commonly by string line and plumb bobs had been introduced, and tunnels were advanced from a succession of closely spaced shafts to provide ventilation.
To save the need for a lining, most ancient tunnels were located in reasonably strong rock, which was broken off spalled by so-called fire quenching, a method involving heating the rock with fire and suddenly cooling it by dousing with water.
Ventilation methods were primitive, often limited to waving a canvas at the mouth of the shaft, and most tunnels claimed the lives of hundreds or even thousands of the slaves used as workers. In ad 41 the Romans used some 30, men for 10 years to push a 3. They worked from shafts feet apart and up to feet deep. Far more attention was paid to ventilation and safety measures when workers were freemen, as shown by archaeological diggings at Hallstatt , Austria, where salt-mine tunnels have been worked since bc.
The first of many major canal tunnels was the Canal du Midi also known as Languedoc tunnel in France , built in —81 by Pierre Riquet as part of the first canal linking the Atlantic and the Mediterranean. With a length of feet and a cross section of 22 by 27 feet, it involved what was probably the first major use of explosives in public-works tunneling, gunpowder placed in holes drilled by handheld iron drills.
Many more canal tunnels were dug in Europe and North America in the 18th and early 19th centuries. Though the canals fell into disuse with the introduction of railroads about , the new form of transport produced a huge increase in tunneling, which continued for nearly years as railroads expanded over the world.
Much pioneer railroad tunneling developed in England. In the United States , the first railroad tunnel was a foot construction on the Allegheny Portage Railroad. Built in —33, it was a combination of canal and railroad systems, carrying canal barges over a summit.
Though plans for a transport link from Boston to the Hudson River had first called for a canal tunnel to pass under the Berkshire Mountains, by , when the Hoosac Tunnel was started, railroads had already established their worth, and the plans were changed to a double-track railroad bore 24 by 22 feet and 4. Initial estimates contemplated completion in 3 years; 21 were actually required, partly because the rock proved too hard for either hand drilling or a primitive power saw.
When the state of Massachusetts finally took over the project, it completed it in at five times the originally estimated cost. Despite frustrations, the Hoosac Tunnel contributed notable advances in tunneling, including one of the first uses of dynamite , the first use of electric firing of explosives, and the introduction of power drills , initially steam and later air, from which there ultimately developed a compressed-air industry. Simultaneously, more spectacular railroad tunnels were being started through the Alps.
Its engineer, Germain Sommeiller , introduced many pioneering techniques, including rail-mounted drill carriages, hydraulic ram air compressors, and construction camps for workers complete with dormitories, family housing, schools, hospitals, a recreation building, and repair shops. Sommeiller also designed an air drill that eventually made it possible to move the tunnel ahead at the rate of 15 feet per day and was used in several later European tunnels until replaced by more durable drills developed in the United States by Simon Ingersoll and others on the Hoosac Tunnel.
As this long tunnel was driven from two headings separated by 7. Ventilation became a major problem, which was solved by the use of forced air from water-powered fans and a horizontal diaphragm at mid-height, forming an exhaust duct at top of the tunnel. Mont Cenis was soon followed by other notable Alpine railroad tunnels: the 9-mile St.
Driving Simplon as two parallel tunnels with frequent crosscut connections considerably aided ventilation and drainage. When one heading was passing under the Kander River valley, a sudden inflow of water, gravel, and broken rock filled the tunnel for a length of 4, feet, burying the entire crew of 25 men.
Though a geologic panel had predicted that the tunnel here would be in solid bedrock far below the bottom of the valley fill, subsequent investigation showed that bedrock lay at a depth of feet, so that at feet the tunnel tapped the Kander River, allowing it and soil of the valley fill to pour into the tunnel, creating a huge depression, or sink, at the surface.
After this lesson in the need for improved geologic investigation, the tunnel was rerouted about one mile 1. Most long-distance rock tunnels have encountered problems with water inflows.
One of the most notorious was the first Japanese Tanna Tunnel, driven through the Takiji Peak in the s. The engineers and crews had to cope with a long succession of extremely large inflows, the first of which killed 16 men and buried 17 others, who were rescued after seven days of tunneling through the debris.
Three years later another major inflow drowned several workers. In the end, Japanese engineers hit on the expedient of digging a parallel drainage tunnel the entire length of the main tunnel. In addition, they resorted to compressed-air tunneling with shield and air lock , a technique almost unheard-of in mountain tunneling. The first use of the shield, by Brunel and his son Isambard, was in on the Wapping-Rotherhithe Tunnel through clay under the Thames River.
In by reducing to a small size 8 feet and by changing to a circular shield plus a lining of cast-iron segments, Peter W. Barlow and his field engineer, James Henry Greathead , were able to complete a second Thames tunnel in only one year as a pedestrian walkway from Tower Hill. In , Greathead made the subaqueous technique really practical by refinements and mechanization of the Brunel-Barlow shield and by adding compressed air pressure inside the tunnel to hold back the outside water pressure.
The first major application of the shield-plus-compressed-air technique occurred in on the London subway with an foot bore, where it accomplished the unheard-of record of seven miles of tunneling without a single fatality. So thoroughly did Greathead develop his procedure that it was used successfully for the next 75 years with no significant change.
A modern Greathead shield illustrates his original developments: miners working under a hood in individual small pockets that can be quickly closed against inflow; shield propelled forward by jacks; permanent lining segments erected under protection of the shield tail; and the whole tunnel pressurized to resist water inflow.
Once subaqueous tunneling became practical, many railroad and subway crossings were constructed with the Greathead shield, and the technique later proved adaptable for the much larger tunnels required for automobiles. Holland and his chief engineer, Ole Singstad, solved the ventilation problem with huge-capacity fans in ventilating buildings at each end, forcing air through a supply duct below the roadway, with an exhaust duct above the ceiling.
Such ventilation provisions significantly increased the tunnel size, requiring about a foot diameter for a two-lane vehicular tunnel.
Many similar vehicular tunnels were built by shield-and-compressed-air methods—including Lincoln and Queens tunnels in New York City , Sumner and Callahan in Boston, and Mersey in Liverpool. Since , however, most subaqueous tunnelers preferred the immersed-tube method, in which long tube sections are prefabricated, towed to the site, sunk in a previously dredged trench, connected to sections already in place, and then covered with backfill.
This basic procedure was first used in its present form on the Detroit River Railroad Tunnel between Detroit and Windsor, Ontario — A prime advantage is the avoidance of high costs and the risks of operating a shield under high air pressure, since work inside the sunken tube is at atmospheric pressure free air.
With ground conditions being favourable a readily cuttable clay-shale , success resulted from a team effort: Jerome O. Ackerman as chief engineer, F. Mittry as initial contractor, and James S. The Oahe mole was partly inspired by work on a pilot tunnel in chalk started under the English Channel for which an air-powered rotary cutting arm, the Beaumont borer, had been invented. A coal-mining version followed, and in a coal saw was used to cut a circumferential slot in chalk for foot-diameter tunnels at Fort Randall Dam in South Dakota.
In a comparable breakthrough for the more difficult excavation of vertical shafts was achieved in the American development of the mechanical raise borer, profiting from earlier trials in Germany. Tunnels and underground excavations Article Media Additional Info. Article Contents. Print print Print.
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Kenneth S. Lane Consulting engineer for dams and tunnels, and soils and rock engineering. See Article History. History Ancient tunnels It is probable that the first tunneling was done by prehistoric people seeking to enlarge their caves. Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now. Load Next Page.
A vertical opening is usually called a shaft. Tunnels have many uses: for mining ores, for transportation—including road vehicles, trains, subways, and canals—and for conducting water and sewage. Underground chambers, often associated with a complex of connecting tunnels and shafts, increasingly are being used for such things as underground hydroelectric-power plants, ore-processing plants, pumping stations, vehicle parking, storage of oil and water, water-treatment plants, warehouses, and light manufacturing; also command centres and other special military needs. True tunnels and chambers are excavated from the inside—with the overlying material left in place—and then lined as necessary to support the adjacent ground. A hillside tunnel entrance is called a portal ; tunnels may also be started from the bottom of a vertical shaft or from the end of a horizontal tunnel driven principally for construction access and called an adit. So-called cut-and-cover tunnels more correctly called conduits are built by excavating from the surface, constructing the structure, and then covering with backfill. Tunnels underwater are now commonly built by the use of an immersed tube : long, prefabricated tube sections are floated to the site, sunk in a prepared trench, and covered with backfill.
Support system performance under different corrosion conditions. Hadjigeorgiou; J. Dorion; E. This paper reports on recent field observations on the performance of support systems under different corrosion environments in Canadian underground mines. Phenomenological data are used to gain a better understanding of the main causes of corrosion in underground metal mines. Preliminary field data collected from five metal mines have been complemented by atmospheric and water sample analysis as well as fractography and metallographic studies. This has identified dominant factors that control the corrosion of support systems.
Tunnels and underground excavations
Hashiba, K. Shafts have a key role as access, transportation, and ventilation routes in mining, tunneling, and underground construction. In addition, the high-level radioactive waste disposal planned in Japan will require the shafts that are deeper than several hundred meters.
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Article details Download article PDF. Proceedings Journals Books. Series: Advances in Engineering Research. Proceedings Article. Construction of hydro power projects in the Himalayan region poses various problems which can have direct implication on the cost and time schedule of the projects.
Вы делали ему искусственное дыхание. На лице старика появилось виноватое выражение. - Увы, я не знаю, как это делается. Я вызвал скорую. Беккер вспомнил синеватый шрам на груди Танкадо.
Этим я и занимался сегодня весь день - считывал тексты с его терминала, чтобы быть наготове, когда он сделает первый шаг, чтобы вмонтировать этот чертов черный ход. Вот почему я скачал на свой компьютер его электронную почту. Как доказательство, что он отслеживал все связанное с Цифровой крепостью. Я собирался передать всю эту информацию в прессу. Сердце у Сьюзан бешено забилось.
Support in Hard rock Underground Mines. 2. Introduction Shotcrete is used very widely in civil engineering construction but is not used by the mining industry.
Понадобятся лучшие алгоритмы, чтобы противостоять компьютерам завтрашнего дня. - Такова Цифровая крепость. - Конечно. Алгоритм, не подающийся грубой силе, никогда не устареет, какими бы мощными ни стали компьютеры, взламывающие шифры. Когда-нибудь он станет мировым стандартом. Сьюзан глубоко вздохнула.
Каждый компьютер в мире, от обычных ПК, продающихся в магазинах торговой сети Радиошэк, и до систем спутникового управления и контроля НАСА, имеет встроенное страховочное приспособление как раз на случай таких ситуаций, называемое отключение из розетки. Полностью отключив электроснабжение, они могли бы остановить работу ТРАНСТЕКСТА, а вирус удалить позже, просто заново отформатировав жесткие диски компьютера. В процессе форматирования стирается память машины - информация, программное обеспечение, вирусы, одним словом - все, и в большинстве случаев переформатирование означает потерю тысяч файлов, многих лет труда. Но ТРАНСТЕКСТ не был обычным компьютером - его можно было отформатировать практически без потерь. Машины параллельной обработки сконструированы для того, чтобы думать, а не запоминать. В ТРАНСТЕКСТЕ практически ничего не складировалось, взломанные шифры немедленно отсылались в главный банк данных АНБ, чтобы… Сьюзан стало плохо.
Клубы пара вырвались наружу, подкрашенные снизу в красный цвет контрольными лампами. Далекий гул генераторов теперь превратился в громкое урчание. Чатрукьян выпрямился и посмотрел. То, что он увидел, больше напоминало вход в преисподнюю, а не в служебное помещение. Узкая лестница спускалась к платформе, за которой тоже виднелись ступеньки, и все это было окутано красным туманом.
Размышляя об этом, Сьюзан вдруг вспомнила фразу, сказанную Стратмором: Я попытался запустить Следопыта самостоятельно, но информация, которую он выдал, оказалась бессмысленной.
Это был девиз туристского бюро Севильи. - Она назвала вам свое имя. - Нет.
После этого он позвонил бы Стратмору, считал пароль с кольца на своем пальце и в последнюю минуту спас главный банк данных АНБ. Вдоволь посмеявшись, он исчез бы насовсем, превратившись в легенду Фонда электронных границ. Сьюзан стукнула кулаком по столу: - Нам необходимо это кольцо.
Северная Дакота - это Хейл. Но Стратмор смотрел на молодого сотрудника лаборатории систем безопасности. Коммандер спускался по лестнице, ни на мгновение не сводя с него глаз. Он быстро подошел к ним и остановился в нескольких сантиметрах от дрожащего Чатрукьяна. - Вы что-то сказали.
Такси было уже совсем рядом, и, бросив взгляд влево, Беккер увидел, что Халохот снова поднимает револьвер. Повинуясь инстинкту, он резко нажал на тормоза, но мотоцикл не остановился на скользком от машинного масла полу. Веспу понесло. Рядом раздался оглушающий визг тормозов такси, его лысая резина заскользила по полу. Машина завертелась в облаке выхлопных газов совсем рядом с мотоциклом Беккера.
Юбка девушки высоко задралась от ветра, но она не обращала на это ни малейшего внимания. Беккер рванулся к. Неужели все это происходит со мной? - подумал .
Шифр-убийца? - переспросил Бринкерхофф. Джабба кивнул: - Да. Нужно ввести ключ, останавливающий червя. Все очень все .
ГЛАВА 19 - А вдруг кто-то еще хочет заполучить это кольцо? - спросила Сьюзан, внезапно заволновавшись.