Penetrometer is a device for making standard penetration test. The frustum shape of a split-spoon is the edge of penetrometer. This tube has 35.5 mm inner diameter, 50.8 mm outer diameter, 6.81 kg total weight and 81.3 cm height. Relationship between frequency of granular soil and consistency of cohesive soil is determined for proceeding the sampler’s essential number of strokes during the sample receiver is inserted in the soil.
During the drilling that reaches a certain depth, the drilling rig is pulled outside and the sample receiver is put down. The tube is hammered 45.7 cm with a tamper, that is dropped from a height of 76.2 cm, weight of 63.5 kg into the soil and the required number of strokes for every 15.2 cm penetration into the soil are recorded. Standard penetration resistance (N30) is contained from required total blow count for entering the second and third 15.2 cm parts.
When making practical inquiries about sequence of sandy ground by the help of SPT, it is possible to a take sample. The other advantages of the test is; determining the soil profile continuously and fast, the results do not depend on the operator who is testing, it is suitable for the soft clays and the silty soil that taking sample is very difficult.