Содержание

DRAINAGE

Терпигорева В.Д., Матвеев С.Д.

      Water enters into underground workings principally by percolating through the previous strata. It is estimated [§ 5, 1, 6)] nearly 80 per cent of the rainfall sinks into the ground and through the porous rocks, sands, and gravels beneath. The quantity met with [§ 5, 2, § 9] in mines depends upon the depth and nature of the overlying formations. Drift openings usually have to contend [§ 6, 2] with less water than shafts. Strata which are regular and of dense homogeneous material resist the passage of water, whereas measures which are faulted, creviced, or broken make the ingress of water easy. The tendency of water to follow lines of weakness is well illustrated in meeting with a clay vein. Water may be found issuing from these in large quantities, the loose adhesion between the clay rock and the penetrated strata providing the necessary channels [§ 5, 2, в)].
      The yearly rainfall of a region enters largely into the quantity of underground water.
      The time required for a protracted rainfall to reach the workings depends on the thickness, and character of the strata penetrated. In shallow mines, the effect of a rainy period is quickly noticeable. If the outcrop be pierced at many points, so much water may enter the mine as to flood the working places. Thus it was found that [§ 5, 1, 6)] the pumping requirements were heaviest in the months immediately following the greatest precipitation. Inasmuch as the depth from the surface varied from 200 to 400 ft., the record would indicate that the penetrating waters required a month to travel this distance.
      Frequently mines which are naturally dry, remain so only until the pillars are drawn or coal is worked out and breaks are made, reaching to the surface. This may release large quantities of water contained in the overlying strata; channels of surface springs may be broken and their contents diverted into the mine, and wells and cisterns may be completely drained. Moreover, the rainfall finds easy entrance through the fissures. Precautions should always be taken [§ 6, 2] not to break the intervening strata directly under a water course or a standing body of water. If possible the water should be diverted, or, in the case of a standing body, drainage, or pumping to dryness, should be resorted to.
      Water sometimes finds its way into the mine from adjoining abandoned workings by seeping underneath the barrier pillars or workings. When such standing quantities are suddenly released by the accidental penetration of rooms or entries, the volume of water released may be sufficient to flood the mine and drown the workers.
      While underground workings will always contain more or less water, it is possible, by the exercise of proper precautions, to prevent much of the surface water from entering the mine.
      In shallow mines, where caves or sinkages have, been formed on the hill sides, the water may be diverted by ditching around the top and sides of the cavity. A wise precaution is to have the discharge from all pumps at a proper distance from the shafts. Where the coal seam is reached by shafts in which the water is not sealed off, a considerable portion of the work of the pumps may consist of handling the water which comes down these openings. Water rings are generally placed in wet-timbered shafts and the water that collects in these may be pumped to the surface, rather than allowing it to gravitate to the bottom, there to add to the burden of the main pumps.

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