In Situ Shear Wave Velocity by Cross-Hole Method

The cross-hole seismic survey technique is presented as a means of determining in situ shear wave velocity. By this method the travel time for body waves to travel between two points in a soil mass is measured. Body waves may be either compression or shear waves. Emphasis is placed on identification of the shear wave because it is directly used to calculate the dynamic shear modulus of the soil and can be measured above or below the water table. A general procedure followed in performing the test is described. Typical travel time records of arriving energy are shown and identification of the compression and shear wave arrivals made. Preliminary tests demonstrating the validity and use of the method are presented. Three case studies using the method under various field conditions are also presented.