The shaft resistance can be obtained by integrating the available shear strength along the shaft, while the base resistance can be found from the bearing capacity for a deep foundation. Holes when drilled should be concreted within the same day, as leaving the hole open can lead to softening of the soil along the shaft with resultant loss of bearing capacity. Piles may be used singly or in groups, and if used in groups, they tend to interact with one another, so that if one pile is loaded, then it causes the surrounding piles to settle. Jet grouted piles are formed by drilling to the required depth and then injecting high pressure grout that cuts away soil and forms a mix of soil and cement slurry. The ultimate skin friction values were based largely on the constant normal stiffness data, while the ultimate end bearing values for piles were assessed on the basis of correlations with unconfined compressive strength data.