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摘要
The swelling behaviour of expansive soils is significant in geotechnical engineering since it causes severe damage to civil structures. The swelling characteristics need to be well known for satisfactorily safe and economic engineering designs. A direct determination of the swelling characteristics requires considerable time and money, involving serious experimental effort. Alternatively, several indirect estimation techniques developed using empirical regression models available in literature are widely used in practice. These empirical estimation techniques have generally been assessed as a function of the soil properties, i.e., consistency limits, density, moisture content, clay fraction and type, and cation-exchange capacity.
This paper describes the dependence of the percentage swell (S%) and the swell pressure (asp) obtained from a free-swell (FS) test and a constant-volume swell (CVS) test, and the primary swell time (PST), in which almost 90% of the swelling occurs as strain, which is considered as a new swelling characteristic in this study, on the hydraulic conductivity (k) controlled by a change in the gradation of compacted expansive soils. In addition, the rate of primary swelling (C-ps), which is the primary swelling phase's slope of the curve of percentage swell vs. log time, and the ratio of (C-ps/k) were used to analyse their relationships with the swelling characteristics.
This study provides the empirical methods that can be utilized to obtain indirect estimations of the percentage swell (S%), swell pressure (asp) and primary swell time (PST) depending on k, Cps and C-ps/k, in addition to, or with, the conventional parameters. The correlation coefficients of the regression analysis, having high performance, and indicating strong relationships between the swelling characteristics and the indices proposed in this study, state that these empirical prediction equations can be used safely in engineering practice.
- 出版日期2017
