Prob. A falling head permeability test was performed on a sample of silty sand. The time required for the head to fall in the standpipe from the 60 cm to 30 cm mark was 70 minutes. The sectional area of the standpipe was 1.25 cm². If the height and diameter of the sample were respectively 100 mm and 90 mm, determine the value of K.

A constant head permeability test is performed on soil that is 4 cm2, and 2.5cm long. The head difference applied during the test is 20 cm and 7 cm3 is collected over a time of 100 sec. Then, falling head test is conducted on the same soil specimen at the same time  (t1 – t2 = 100 sec), and the standpipe diameter is 0.8 cm. If the average head during the test should be 18 cm, what are h1 and h2 values, provide step by step solution solving h1 and h2 values.

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