Friday, October 26, 2012

Dutch cone test - SITE EXPLORATION.

This test is used for getting a continuous record of the resistance of soil by penetrating steadily under static pressurc a cone with a base of 10cm^2 (3.6 cm in dia.) and an angle of 60ยบ  at vertex. The cone is carried at the lower end of a steel driving rod which passes through a steel tube (mantle) with external diameter equal to the base of the cone. Either the cone or the tube, or both together can be forced into the soil by means of jack. To know the cone resistance, the cone along is first forced down for a distance of 8 cm and the maximum value of resistance Is recorded. The steel tube is then pushed down upto the cone, and both together are further penetrated through a depth of 20 cm to give the total of cone resistance and the frictional resistance along the tube.

The Cone test is considered very useful in determining the bearing capacity of pits in cohesionless soils, particularly in fine sands of varying density. The cone resistance qc (kg/cm^2) is approximately equal to 5 to 10 times the penetration resistance N.

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