CONE PENETRATION TESTING AND SITE EXPLORATION IN EVALUATING THE LIQUEFACTION RESISTANCE OF SANDS AND SILTY SANDS E. J. Newman 1 , T. D. Stark 2 , and S. M. Olson 3 ABSTRACT Refined relationships between cone penetration tip resistance and liquefaction resistance of sandy soils are presented to facilitate use of the cone penetration test (CPT) in liquefaction studies. The proposed relationships are based on a database of field case histories where CPTs were performed and adjacent borings were drilled and sampled to confirm soil type and fines content. The newly-developed database employs stringent selection criteria to minimize inconsistencies in CPT sounding selection and interpretation that are present in other level-ground liquefaction databases, as well as to aid in the addition of data by others. Applying these proposed stringent criteria results in a reduced, but more defensible, database. Additionally, the effect of fines content on liquefaction resistance is quantified by a fines content adjustment in a form that facilitates use in practice. Introduction Both the cone penetration test (CPT) and the standard penetration test (SPT) offer advantages and disadvantages in estimating soil properties. The cone penetration test is more economical, allowing practitioners to perform more tests and to gain a better understanding of soil property variability at a site. The continuous profile measured by the CPT reduces uncertainty associated with potential thin layers that may or may not be discovered and sampled when using a conventional sampling interval for the SPT. A disadvantage of the CPT is that commonly used equipment does not retrieve a soil sample for examination or laboratory testing, although considerable empirical data exist to correlate CPT measurements to various soil properties (e.g., Meigh 1987, Kulhawy and Mayne 1990, Lunne et al. 1997). The standard penetration test retrieves a soil sample during the test and, if coordinated with a CPT program, can greatly enhance the CPT data interpretation. To facilitate use of the CPT in level-ground liquefaction analyses, numerous investigators have proposed relationships between liquefaction resistance and CPT measurements (e.g. Stark 1 Graduate research assistant, Dept. of Civil and Environmental Engineering, University of Illinois at Urbana- Champaign, Urbana, IL 61801 2 Professor, Dept. of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 3 Assistant Professor, Dept. of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801