Laboratory method of determining the coefficient of filtration consist of performing experience to the sample taken from the layer of interest to us wodonosnej.motoda laboratory can determine permeability coefficient attempts, and therefore, gives the estimated value of the coefficient for each layer.
It should be emphasized, and the results of laboratory tests are disproportionately more accurate the results obtained on the basis of grain size analyzes. Because of this, experiments with the use of various types, please calculations use appropriately selected patterns. These patterns most often derived from linear law darcy:
V = kJ
where in:
V-speed flow
k - coefficient of filtration (water permeability)
J- hydraulic gradient
speed of descent of water in the permeametrze can be expressed as
v = ds / dt
natoiast hydraulic gradient
K = J / l (ho-s)
substituting the equation (1) expressions (2) and (3) we get
ds / dt = k / l (ho-s)
whence final
k = (s / t) (- ln (1- (sec / ho))
additionally you can replace a word in square brackets to:
@ (S / ho), resulting in k = (l / t) @ (s / ho)
This method allows for fast and sufficiently accurate determination value of the coefficient of filtration pospolek, sandstones thick, medium, small and even dusty. Tube principle Kamieńskiego is to study the speed of water flow through the probe ground, with a changing pressure of the water column (variable drop hydraulic)
List of equipment: winidurowa tube on a tripod, the vessel on the water with a capacity of up to 3 I, gauze, filter paper or granulated gravel, a stopwatch, a thermometer, a ruler with centimeter scale.
Procedure: To winidurowej a closed tube from the bottom of the filters of the filter should be surrounded by a gauze slowly pour a sample of the tested material slowly immersing a tube in the water. The sample should be lightly compacted, and take care of it that material was constantly saturated with water, which you should not allow to pour the dry soil to water (because it will happen stratification), nor submerge the dry probe in the water (air free will occur because attempts). Proba should have a height of 10 cm. At wierzych attempts should wear a pad or 1-2 cm layer of gravel. Experience should be made in two variants:
Option A
Tube should dip to the height attempts in a pan of water, and a whole insert to the large vessel (bowl), see Figure 1. The sample should pour water into the top edge of the tube. At the time of achieving the water posiomu 30 cm enable stopwatch and record the time decreasing levels every 2 cm until completely filter the water through a sample of. Time shall be recorded continuously, naraztajaco. The results should be recorded on Form Factor Test method of filtration tubes Kamieńskiego. Experience must be repeated at least once.
Option B
In this variant, the tube is not inserted into a container with water, but placed over a large vessel (bowl), allowing the water to flow freely, cf. Fig. 2. Further actions are the same as in option A
Measure and note down also the temperature of water used for the study. Then calculate the coefficient of filtration by using rubrics form survey. Value expressions @ (s / ho) should be read with Table 57 or nomogram see. Fig. 253 of the Hydrogeology textbook * General *. As the final result should be taken as the average of the box 14 of the form. the discussion should pay attention to the difference between the results of otrymanymi in both variants, explain to them the reason.
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