In India, more than 20% land contains soils with high plasticity. They are used in their compacted states for the construction of earthen dams, levees, artificial canals, etc. In many instances their use are also seen as the subgrade material in roadways and as a backfill material in retaining walls. The understanding of shear behaviour of this high plasticity soil in its compacted state is utmost importance for the design and analysis of these geotechnical structures. Hence, the aim of this research is to evaluate the shear behaviour of compacted CH soil at small and large strain under cyclic and static loading conditions. The loading in true field condition is not always isotropic in nature and many times it became anisotropic with stress ratio different than one. Hence to encounter this phenomena in static loading, a study was conducted to evaluate the effect of stress paths on undrained shear response of CH soil. Small strain shear modulus variation was also measured in this series of testing and an attempt was made to relate that with large strain deformation behaviour. Usually, clayey soils behaves better than granular soils under cyclic loading conditions. However, the strength loss sometimes became significant to damage the entire structure on it. Therefore, a study was performed in the current research to incorporate the effect of initial static shear under cyclic simple shear loading conditions. The results displayed significant effect of pre-shear condition on cyclic response of CH soil. Many regions of India are arid to semi-arid in nature and due to this, the soils of these regions remained unsaturated most time of a year. To incorporate this moisture variation, a series of experiments were performed on unsaturated CH soil. It was found that the soil-water characteristics curve (SWCC) governs all these responses and they can be explained through a fundamental parameter of matric suction.

I think many of you ‘enjoyed’ the ride of a roller coaster in theme parks. My experience at IIT Gandhinagar also similar to the ride of a rollercoaster: sometimes ups and sometimes down. However, I also eventually enjoyed and right now also enjoying this ride of IITGN. It all started in July of 2016, when I joined this institute as a Start-early PhD student. First few weeks of IITGN gave me a high magnitude of cultural shock. Some of you might be thinking that I am overreacting, but the education system and culture from my B.E. college were entirely different. But within few weeks, I made new friends and slowly I was enjoying the late-night classes, completion of weekly assignments of four to five subjects (that too without plagiarism!!!), hostel life, birthday bashes, late night tea, last-minute completion of course project and many more things. The busiest first year of course work was completed, and now the thesis work began. I joined my research group and met my wonderful and extremely helpful seniors. They made me feel like family and also inspired me to do the same with my juniors. Then another year went with thesis work, course work, the great ‘qualifying exam’, and proposal defence. Now the worst time came as my fellow batchmates (mostly in MTech program) graduated and left the college. But, this hard time also flew away, and the new junior students joined the lab research group. Within no time, I found new friends in them, and everything was again running smooth. Though sometimes the research work gave trouble but eventually it was getting resolved, and today I am thankfully doing my PhD at IITGN. TA work at IITGN sometimes become hectic, but I learn a lot from the experience of TA work and also get a chance to know the fantastic and curious B.Tech guys. In the end, I would like to thank my supervisor Dr Ajanta Sachan for her great support and understanding in every situation. IITGN changed me a lot and gave me high confidence in myself and also triggered the new way of thinking.
Thank you IIT Gandhinagar.