Probing

In the probing method of site exploration, a steel bar of 25 to 40 mm. in diameter with a pointed end is driven in the ground until a hard sub-stratum is reached. The bar is driven by allowing it to fall vertically under its own self weight or by means of a drop hammer. At intervals the bar is drawn out and some idea of the nature of the soil is obtained by examining the soil sticking to the sides of the bar. Probing method is suitable to be performed in places where the soil is soft like clay, gravel or sand. A rough idea of the nature of strata is obtained from the number of blows required to drive the rod inside the ground. Experienced workmen engaged in the execution of the driving operation may be able to judge the soil at various depths by reading the way the rod penetrates into the ground. Probing method is not always to be relied upon completely. More definite analysis should be done to ascertain the results arrived at by this method.