Effects of Borehole Fluid on Standard Penetration Test Results
The standard penetration test (SPT) represents the most widely used in-situ test method for evaluating the liquefaction resistance of saturated soils. Significant progress has been made in recent years in developing correlations between SPT results obtained using different test procedures and equipment in order to develop a higher degree of standardization for SPT testing. One of the heretofore unresolved factors affecting SPT results is the effect of borehole fluid type (for example, water or drilling mud). This paper presents a study in which field data were obtained from SPT performed in adjacent boreholes, some filled with water and others filled with drilling mud, at four different sites in order to investigate this effect. A total of 213 SPT were considered: 147 SPT in mud-filled boreholes and 66 SPT in water-filled boreholes. Borehole fluid type (drilling mud versus water) was found to have no significant effect on STP resistances measured so long as careful and appropriate drilling and sampling procedures are employed.