An experimental study on the secondary deformation of Boom clay

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• 作者：Y.F. Deng^a ; ^b ; ^{noden@seu.edu.cn} ; Y.J. Cui^b ; ^{yujun.cui@enpc.fr} ; A.M. Tang^b ; X.L. Li^c ; ^{xli@sckcen.be} ; X. Sillen^d ; ^{x.sillen@nirond.be}
• 关键词：Boom clay ; oedometer test ; Secondary deformation behavior ; Mechanically dominated rebounding ; Physico-chemically dominated swelling
• 刊名：Applied Clay Science
• 出版年：2012
• 期刊代码：5_01691317
• 类别：ms
• 出版时间：May, 2012
• 卷：59-60
• 期：Complete
• 页码：19-25
• 文件大小：1156 K

摘要

Boom clay formation, a deposit of slightly over-consolidated marine clay that belongs to the Oligocene series in the north east of Belgium, has been studied as a possible host material of nuclear waste disposal. In this context, the long-term deformation behavior of Boom clay is of crucial importance in the performance assessment of the whole storage system. In this study, low and high pressure oedometer tests are carried out; the e-log 蟽鈥?sub>v (void ratio-logarithm of vertical effective stress) and e-log t (void ratio-logarithm of time) curves obtained are used to determine the compression index C_c*, swelling index C_s* and secondary deformation coefficient C_伪 during both loading and unloading. The relationship between C_伪 and the effective stress ratio (蟽鈥?sub>v/蟽鈥?sub>c, vertical effective stress to pre-consolidation stress) is analyzed, and it is observed that C_伪 increases linearly with log 蟽鈥?sub>v/蟽鈥?sub>c. Examination of the ratio of C_伪/C_c* for various soils shows that the secondary deformation behavior of Boom clay is similar to that of shale and mudstone. The relation between C_伪 and C_c* is linear; but the relation between C_伪 and C_s* is bi-linear. The bi-linearity observed is related to two different mechanisms: the mechanically dominated rebounding and the physico-chemically dominated swelling.