Foundation-Settlement of Shallow Foundation from SPT Data

The relationship between compressibility of soil, foundation width and average SPT blow count over the depth of influence was determined by Burland and Burbidge (1985). These relationships were established via statistical analysis based on more than 200 settlement records for foundation sitting on sands and gravels.

The ratio of depth of influence to foundation width decreases with increasing width, should the SPT blow count tends to either increase or remain constant with depth. For the opposite case, the depth of influence shall be taken as two times the foundation width.