Drilling and Insitu Tests

Permeability Test


Permeability test perform to determine permeability coefficient of ground. According to type of groundfalling or constand head permeability test performs. For coarse grained granular soils constant head permeability test and for fine grained soils falling head permeability test performs. Test performs accordng to BS 5930:1999 code.

1. Falling Head Permeability Test

In this method, the borehole is filled with water. The head being measured at intervals of time from the commencement of the test. The readings are taken at the 0, 1, 2, 4, 8, 15, 30th minutes. The depth of the borehole is checked to determine whether any sediment has come out of suspension or whether the bottom of the borehole has heaved during the test period. The test length L, is taken as the difference between the length of the casing and the borehole test depth.

2. Constant head Permeability test

A constant head test is normally conducted as an inflow test in which arrangements are made for water to flow into the ground under a sensibly constant head. It is essential to use clean water. The rate of flow water is adjusted until a constant head is achieved and, in which the actual rate of flow is measured and recorded at 5 minutes of intervals from the commencement of the test. The total water loss is recorded for 10 minutes, where the readings are recorded at the beginning of the test-- the zero reading, at the fifth minute and finally at tenth minute of the test. The test length, L is taken as the difference value between the length of the casing and the borehole test depth.

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