期刊名称：IOP Conference Series: Earth and Environmental Science
印刷版ISSN：1755-1307
电子版ISSN：1755-1315
出版年度：2019
卷号：304
期号：5
页码：1-11
DOI：10.1088/1755-1315/304/5/052022
出版社：IOP Publishing
摘要：Undrained shear strength (Su) of foundation soils were estimated from the results of pressuremeter tests conducted on slightly overconsolidated and overconsolidated clays in two test sites. To investigate the effects of overconsolidation ratio (OCR) and pressuremeter of limited length on the undrained shear strength of clays, three kinds of evaluation methods based on the cavity expansion theory were used in this study.Where the direct traditional method suggested by Gibson and Anderson ignores the effect of pressuremeter of limited length and OCR, the analytic method based on modified Cambridge model proposed by Cao only considers the effect of OCR, the finite element method (FEM) in view of the modified Cambridge model take the effects both of pressuremeter of limited length and OCR into account. The results show that the undrained shear strength obtained from the direct traditional method is significantly smaller than that obtained from the analytic method due to the effect of OCR, and with the increase of OCR, the difference between the two increases. The undrained shear strength estimated from the analytical method is larger than that estimated from the FEM in virtue of the effect of pressuremeter of umlimited length, and with the increase in OCR, the effect of pressuremeter of limited length rapidly decreased.When performing a PMT in clay with pressuremeter of limited length, there is a critical value of OCR, where the length effect is higher than the OCR effect when the OCR is below this critical value, while the effect of OCR and the length cancel each other out when the OCR is above this critical value. The threshold value is predicted to be 23 for the OC silty clay in case 1,and the actual value of the threshold is 34 for the OC silty clay in case 2.
