Procedural Effects on SPT Results at a Fluvial Sand Site

Abstract

Different procedures for performing the standard penetration test (SPT) were employed during the site investigation at a fluvial sand site along the Ohio River. Comparison of the collected data shows that the SPT blow counts, i.e. N-values, were significantly affected by the test procedure used, due to the “flow-sand” phenomenon that occurred in the sandy soils below the groundwater table. The test procedure used can also have an effect on the laboratory test results obtained from the soil samples, such as grain size distribution. Based on experience at this site, reasonable SPT results can be achieved using either the mud rotary drilling method or the hollow stem auger method; however, if the hollow stem auger method is used, the insides of the augers need to be filled with bentonite mud during the test, and the mud should be added each time the augers are advanced.