关键词: 球形贯入仪, 离心模型试验, 大变形有限元, 抗剪强度, 土体流动机制

Abstract: Full-flow ball penetrometers have been used widely in centrifuge testing for characterizing the undrained shear strength of soil sample. However, the soil flow mechanism and bearing capacity factor of ball penetrometers in centrifuge is significantly different from that of in the field tests, which induced by that the ball-soil frictional coefficient and the ratio of larger shaft diameter and cross-area of centrifuge test is different from that of in field tests. Large deformation finite element analyses are carried out to investigate the behaviour of ball penetrating into uniform clay to quantify the bearing capacity. Prior to conduct parametrical study, the plasticity solutions present good agreement with other previously published finite element results and experimental data. The roughness of ball has little effect on the critical depth of the cavity and the critical deep failure depth. The area ratio is shown to have significant influence on the shallow and deep bearing factors, the critical cavity depth, and the critical deep failure depth. Numerous formulas are proposed to quantify those effects to interpret the undrained shear strength profile, and to provide guidance for its application of ball penetrometers in centrifuge testing.

Key words: ball penetromter, centrifuge model test, large deformation finite element (LDFE), shear strength, soil flow mechanism