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  2. Burro Schmidt Tunnel - Wikipedia

    en.wikipedia.org/wiki/Burro_Schmidt_Tunnel

    Inside the tunnel. The historical Burro Schmidt Tunnel is located in the El Paso Mountains of the northern Mojave Desert, in eastern Kern County, southern California.. It is a 0.5-mile (0.80 km) mining tunnel dug with hand tools and dynamite over a 38-year period by William "Burro" H. Schmidt (1871–1954).

  3. Through-the-earth mine communications - Wikipedia

    en.wikipedia.org/wiki/Through-the-earth_mine...

    Portable magnetic-loop cave radios have been used by cavers for two-way communication and cave surveying since the 1960s. [1] In a typical setup the transmitting loop, consisting of many turns of copper wire, is oriented horizontally within the cave using a spirit level, and driven at a few kHz. Though such a small antenna is a very poor ...

  4. Sistema Cheve - Wikipedia

    en.wikipedia.org/wiki/Sistema_Cheve

    The integration of the entire system will produce a 2,597 metres (8,520 ft) deep cave and would represent the deepest cave in the world. [11] [12] During the years 2017, 2018 and 2019 Cheve Cave reached 55 kilometres (34 miles) in length and a depth of 1,524 metres (5,000 ft) compared to the Palomitas cave entrance [13]

  5. Cave digging - Wikipedia

    en.wikipedia.org/wiki/Cave_digging

    Cave digging usually begins with a survey of mountains and valleys in karst topography searching for new caves, with the goal of creating accessible entrances. [1] Whether outside an inaccessible cave or inside an already accessible cave, when spaces are evident on the other side of blocked passages, many strategies can be used to widen ...

  6. Pipe recovery operations - Wikipedia

    en.wikipedia.org/wiki/Pipe_recovery_operations

    Cave-in Stuck Pipe. An unstable formation can result in a cave in. The collapse of the formation can pin the pipe inside the wellbore preventing its movement. Mechanically Stuck Pipe. This can be the result of objects, i.e. slips or pipe wrenches, being dropped down the hole lodging against the BHA. Bent 2 7/8" Tubing Communication between Wells

  7. Treak Cliff Cavern - Wikipedia

    en.wikipedia.org/wiki/Treak_Cliff_Cavern

    Treak Cliff Cavern is a show cave near Castleton in Derbyshire, England. It is part of the Castleton Site of Special Scientific Interest [4] and one of only two sites where the ornamental mineral Blue John is still excavated (the other is the nearby Blue John Cavern). [5]

  8. Cave-in - Wikipedia

    en.wikipedia.org/wiki/Cave-in

    A cave-in is a collapse of a geologic formation, mine or structure which may occur during mining, tunneling, or steep-walled excavation such as trenching. Geologic structures prone to spontaneous cave-ins include alvar , tsingy and other limestone formations, but can also include lava tubes and a variety of other subsurface rock formations.

  9. Natural Tunnel State Park - Wikipedia

    en.wikipedia.org/wiki/Natural_Tunnel_State_Park

    Natural Tunnel State Park is a Virginia state park, centered on the Natural Tunnel, a massive naturally formed cave that is so large it is used as a railroad tunnel.It is located in the Appalachian Mountains near Duffield in Scott County, Virginia.