Strength variability in lime-cement columns and its effect on the reliability of embankments

  • Mohammed Salim Al-Naqshabandy, Håkan Stille, Mohammed Al-Naqshabandy
  • Published 2012


Iraq. I would like to take this opportunity to express my acknowledgement to the people who made the work of this thesis to be possible. I must express my appreciation to my supervisor Professor Stefan Larsson, without whom this work would not have been possible, and I look forward to continuing and completing this work with him. Special thanks are due to Professor Håkan Stille for giving me an opportunity to do the present work at the Division of Soil and Rock Mechanics, and for his valuable comments on the work. I would also like to thank my colleagues from the Division of Soil and Rock Mechanics, in particular Lena Wennerlund and Zein-Eddine Merouani. Finally, I would like to express my special gratitude to my family and my parents for their support. Abstract Ground improvement by deep mixing (DM) is a generic term used for a number of methods in which a binding agent, often lime and/or cement, is mechanically mixed with the soil to increase its engineering properties. The inherent variability with respect to the engineering properties of the improved soil is high due to the variations in geology and the complex mixing process. High variability introduces uncertainty in estimating improved soil properties and the performance of the structure. Current design methodology deals with soil properties deterministically and the uncertainties involved are incorporated in a single value represented by a total factor of safety (FS). The chosen FS is highly dependent on the engineer's judgment and past experience, in which both of these factors vary between different geotechnical designers. Therefore, current design methodology used in practice for DM does not deal with uncertainties in a rational way. In order to design a geotechnical system with the desired level of confidence, the uncertainties involved must be integrated in the DM design. This can be achieved by using reliability-based design (RBD) methods. The research work in this thesis is presented as a collection of three papers. In the first paper, a comprehensive statistical analysis of cone penetration test (CPT) data is described. The objective was to make a contribution to empirical knowledge by evaluating the strength variability of lime-cement columns within the group of tested columns. In the second paper, the effect of the spatial variability and statistical uncertainty with regard to the embankment's reliability was investigated within the framework of RBD. The study in the third paper investigated the strength …

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@inproceedings{AlNaqshabandy2012StrengthVI, title={Strength variability in lime-cement columns and its effect on the reliability of embankments}, author={Mohammed Salim Al-Naqshabandy and H{\aa}kan Stille and Mohammed Al-Naqshabandy}, year={2012} }