The Influence of Test Procedure on Correlation of Atterberg Limits with Liquefaction in Fine-Grained Soils
Liquefaction potential of fine-grained soil deposits is today judged, in part, based on an observed correlation of Atterberg limits to field performance of soils shaken by the 1976 Tangshan earthquake in the People´s Republic of China (PRC). Criteria were subsequently developed and adopted into current liquefaction potential evaluation practice without regard to the test procedures used to measure liquid and plastic limits in the PRC. Liquid and plastic limits tests are, in fact, performed in the PRC using a special laboratory fall cone penetrometer apparatus. An experimental study was made to compare Atterberg limits determined for low plasticity artificial soil mixtures and a limited number of split spoon samples using U.S. and PRC standard procedures. Study results, corroborated by earlier published comparisons of Casagrande-type percussion tests and various fall cone devices, indicate that liquid limits produced by the Casagrande test consistently exceed those produced using the PRC fall cone by about 4% (water content). The lineal extent of foundation soils at Sardis Dam, Mississippi judged to require remedial action against liquefaction varied significantly with fines content, liquid limit, and natural water content; the impact of this study on preliminary estimates of the extent of the dam requiring remedial action is briefly discussed.