Application of N-value to design of foundations in Japan

Abstract

Today, in Japan, the most popularly used method of sounding is the standard penetration test (S.P.T.). However, neither the mechanism of the S.P.T., accuracy of N-value measurements nor accuracy of estimates of the ground constants from the N-value have been discussed much. In this chapter, the authors introduce the present conditions on application of the N-value. The safety factor in the calculation formula of the bearing capacity of pile in road bridge foundations is examined. Distribution of this ratio is nearly logarithmico-normal for all types of piles. The coefficient of variation representing the accuracy of the formula is the smallest with the driven pile and largest with the bored pile. The driven pile is a method used since a long ago and much work has been carried out on it so that it seems the accuracy of its formula has been improved.

Topics & Concepts