![]() In cases where mining operations cut across an entire water-bearing stratum it is necessary to supplement draw-down with drainage. Open-drainage pumping equipment is used to pump ground water that flows into foundation pits at construction projects. All water-bearing strata revealed by the well are drained by this device, and vacuuming is done by means of the ejector, which speeds the draining process. The vacuum-concentric well device consists of an ejection well point with a filter jacket running the entire height of the water-bearing horizon. A vacuum-concentric well drawdown device was developed in the USSR in 1967 for the complex conditions of draining alternating seams of water-bearing and water-resistant rock. The ejector well points are recommended for use in water-bearing sands of uniform composition and structure that have a seepage coefficient of up to 0.1 m per day. Earthquake vibrations in the dams proximity can cause it to fail (Fattah et. Each well point has a water-jet lifter or ejector at the bottom of the installation. An earth dam is a dense artificial embankment built to hold water for agricultural, industrial, or drinking purposes. The pump consists of ejector well points, centrifugal pumps, and distributing and collector pipelines. Many traditional analysis techniques are derived using the drawdown test as a basis. Drawdown by means of ejector pumps is possible up to a depth of 22 m. Pressure drawdown tests can be defined as a series of bottom-hole pressure measurements completed during a period of flow at a constant producing rate. The best results using light well points are obtained in water-bearing sands of uniform composition and with seepage coefficients of 1-5 m per day. For drawdown to more than 5 m, well points are installed in several tiers. Light well points permit drawdown to depths of 4-5 m when the length of the working member of the well points is up to 8 m. Drawdown utilizing drill holes equipped with sucker-rod or centrifugal borehole pumps makes it possible to lower the water level to as deep as 300 m. Water drawdown is achieved by various means depending on the depths of the workings being drained and on the permeability properties of the rock. 103 other terms for drawdown- words and phrases with similar meaning. The temporary lowering of the level or pressure of ground water when constructing foundation pits, mining mineral deposits, driving tunnels, or constructing subways. Another way to say Drawdown Synonyms for Drawdown (other words and phrases for Drawdown).
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