Influence of the initial water content and dry density on the soil–water retention curve and the shrinkage behavior of a compacted clay
- 1.1k Downloads
The paper presents the results of an experimental study on the effects of the initial water content and dry density on the soil–water retention curve and the shrinkage behavior of a compacted Lias-clay. The initial conditions after compaction (initial water content and initial dry density) have been chosen on the basis of three Proctor tests of different compaction efforts. According to the eight chosen initial conditions clay samples have been compacted statically. The relation between total suction and water content was determined for the drying path starting from the initial conditions without previous saturation of the specimens. A chilled-mirror dew-point hygrometer was used for the suction measurements. For the investigation of the shrinkage behavior cylindrical specimens were dried to desired water contents step-by-step without previous saturation. The volume of the specimens was measured by means of a caliper. Based on the test results the influence of different initial conditions on the soil suction and the shrinkage behavior is analyzed. The soil–water retention curves obtained in terms of the gravimetric water content are independent of the initial dry density. At water contents above approximately 11–12.5% a strong influence of the compaction water content is observed. At smaller water contents, the soil–water retention curve is independent of the compaction water content. The results of the shrinkage tests show that the influence of the compaction dry density on the shrinkage behavior is negligible. Similar to the drying behavior of saturated samples a primary and a residual drying process could be distinguished. The primary drying process is strongly influenced by the initial water content. In contrast, the rate of the volume change of the residual drying process is unaffected by the initial water content.
KeywordsClay Compaction Dew-point hygrometer Shrinkage Soil–water retention curve Suction Unsaturated soils
The authors are grateful to Dr. M. Boso for lively discussion and helpful suggestions. They also wish to thank the anonymous reviewers for their constructive comments.
- 1.Agus S, and Schanz T (2005) Comparison of four methods for measuring total suction. Vadose Zone J (4):1087–1095Google Scholar
- 2.Barden L, Sides GR (1970) Engineering behavior and structure of compacted clay. J Soil Mech Found Div (ASCE) (96(SM 4)):1171–1200Google Scholar
- 3.Boso M (2005) Shear strength behaviour of a reconstituted partially saturated clayey silt. PhD dissertation, Università degli Studi di TrentoGoogle Scholar
- 8.Fredlund DG, Rahardjo H (1993) Soil mechanics for unsaturated soils. Wiley, New YorkGoogle Scholar
- 9.Haines W (1923) The volume-change associated with variations of water content in soil. J Agric Sci 13:296–310Google Scholar
- 12.Mitchell JK, Soga K (2005) Fundamentals of soil behavior. Wiley, New YorkGoogle Scholar
- 13.Ng CWW, Pang YW (2000a) Influence of stress state on soil-water characteristics and slope stability. J Geotech Geoenviron Eng 2000:167–188Google Scholar
- 16.Romero E, Vaunat J (2000) Retention curves of deformable clays. In: Proceedings of an international workshop on unsaturated soils, experimental evidence and theoretical approaches in unsaturated soils. Trento, pp 91–106Google Scholar
- 18.Sun D, Sheng DC, Cui HB, Li J (2006) Effect of density on the soil–water-retention behaviour of compacted soil, proceedings of the fourth international conference on unsaturated soils. Ariz, 2006, Published by ASCE 1:1338–1347Google Scholar
- 23.van Genuchten MTh (1980) A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci Soc Am J 44:892–898Google Scholar