CORRELATION OF N VALUE WITH S-WAVE VELOCITY AND SHEAR MODULUS

The velocity of S waves in the ground has come to be acknowledged as the most important geophysical property to be dealt with in seismic microzoning, earthquake engineering — which deals with the dynamic interrelationship between the ground and structures — as well as in the structural engineering fields of civil engineering and architecture. In 1967 the authors began research on the practical application of in situ S wave velocity measurement. Velocity distribution of P and S waves is obtained by directly measuring arrival time values along the depth of the borehole. The experience has shown that for S wave velocity measurement, plank hammering is generally usable for depths of around 100 m, and has been used at depths of up to 350 m in quite areas. In contrast to this, there is a tendency for S wave velocity values to gather around a fixed value for each classification.