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  2. Shaft sinking - Wikipedia

    en.wikipedia.org/wiki/Shaft_sinking

    Where the depth of bedrock is too great to for a box cut to be economically viable, or the bedrock is not strong enough, civil engineering techniques such as diaphragm walls or concrete piles may be used to create a deep foundation instead. Pre-Sink. The pre-sink is the excavation and support of the first 60 – 100 metres of the shaft barrel ...

  3. Pore pressure gradient - Wikipedia

    en.wikipedia.org/wiki/Pore_pressure_gradient

    Using the figures above, we can calculate the maximum pressure at various depths in an offshore oil well. Saltwater is 0.444 psi/ft (2.5% higher than fresh water but this not general and depends on salt concentration in water) Pore pressure in the rock could be as high as 1.0 psi/ft of depth (19.25 lb/gal)

  4. List of deepest mines - Wikipedia

    en.wikipedia.org/wiki/List_of_deepest_mines

    This list of deepest mines includes operational and non-operational mines that are at least 2,212 m (7,257 ft), which is the depth of Veryovkina Cave, the deepest known natural cave in the world. The depth measurements in this list represent the difference in elevation from the entrance of the mine to the deepest excavated point.

  5. Exploration diamond drilling - Wikipedia

    en.wikipedia.org/wiki/Exploration_diamond_drilling

    Exploration diamond drilling differs from other geological drilling (such as Reverse Circulation (RC) Drilling [3]) in that a solid core is extracted from depth, for examination on the surface. The key technology of the diamond drill is the actual diamond bit itself. [4] It is composed of industrial diamonds set into a soft metallic matrix.

  6. Knoop hardness test - Wikipedia

    en.wikipedia.org/wiki/Knoop_hardness_test

    A pyramidal diamond point is pressed into the polished surface of the test material with a known (often 100 g) load, for a specified dwell time, and the resulting indentation is measured using a microscope. The geometry of this indenter is an extended pyramid with the length to width ratio being 7:1 and respective face angles are 172 degrees ...

  7. Rockwell hardness test - Wikipedia

    en.wikipedia.org/wiki/Rockwell_hardness_test

    The depth of penetration from the zero datum is measured, on which a harder material gives a lower measure. That is, the penetration depth and hardness are inversely proportional. The Rockwell test does not use any optical equipment to measure the hardness indention, rather all calculations are done within the machine to measure the indention ...

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  9. Attenuated total reflectance - Wikipedia

    en.wikipedia.org/wiki/Attenuated_total_reflectance

    The excellent mechanical properties of diamond make it an ideal material for ATR, particularly when studying very hard solids, although the broad diamond phonon band between 2600 and 1900 cm −1 significantly decreases signal to noise in this region. The shape of the crystal depends on the type of spectrometer and nature of the sample.