a b s t r a c tThe objective of the study is to investigate the influence of geochemical processes on the geomechanical response of overburden during and after CO 2 injection. In the current study, coupled multiphase fluid flow and geomechanical modeling with geochemical processes were performed to simulate large-scale injection of CO 2 (up to 10 million metric tonnes per year) into a deep saline aquifer over the long-term (up to 1000 years). The geochemical modeling results show that geochemical processes, such as mineral dissolution and precipitation, do not have a significant influence on reservoir rock porosity (about 2% reduction). Modeling results show that the inclusion of geochemical reactions in the coupled fluid flow and geomechanical models do not have any significant influence on the computed pressure and ground displacements due to CO 2 injection for the typical mineralogical composition considered in this study. In other words, a coupled single-phase fluid flow and geomechanical model would give similar results at a significantly lower computational effort.

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Underground conduits have been used to improve living standards of people since the development of civilization. Buried pipes are used in various applications such as highway drainage, sewerage and conveyance systems. Time dependent properties such as creep associated with thermoplastic (HDPE and PVC) and concrete materials may reduce the expected design life of pipes under field conditions. The objective of this research work was to examine the long term performance of buried pipes used in highway applications by using the finite element method. The variables investigated in this research include types of pipe material, pipe diameter, fill height, pipe backfill material, and trench width. Corrugated high density polyethylene (HDPE), solid wall polyvinyl chloride (PVC), reinforced concrete (RCP), and corrugated steel pipes (CSP) have been considered in this study. The influence of trench widths and time dependent material properties such as creep of pipe materials on the performance of buried pipes was investigated for a time period of 50 years under different loading conditions (dead and live loads).The performance of pipe under fill heights ranging from 10 feet (3 m) to 50 feet (15 m) and trench width ratios varying from 1.5 to 2.5 have been analyzed. Trench width ratio can be defined as the trench width divided by the mean diameter of the pipe. Results show that almost 60% to 80% of pipe deflections occur during the first year of installation for all the pipes. This percentage depends on the pipe material and the loads. For PVC pipes, the deflection in the first year is about 70% of the total deflection. For HDPE pipes, this percentage is 60 % to 80%. The results from the numerical analyses suggest that a trench width as low as 1.5 times the diameter of the pipe can be used to install pipes under fill heights up to 40 feet (12 m) without any failure. For PVC pipes, the fill height could be as high as 50 feet for a trench width ratio of 1.5. However, HDPE pipes exhibit the possibility of failure at 50 feet (15 m) burial depth under the combination of live and dead loads. Computed deflections in concrete and steel pipes are small and hence could be installed up to depths of 50 feet without meeting the pipe failure criterion. iii ACKNOWLEDGEMENT I would like to take this opportunity to thank several people who played a vital role in the successful completion of this thesis. First and foremost, I would like to thank my advisor and committee chairman, Dr. Hema Siriwardane, for providing his valuable guidance and continuous support throughout this project. I thank Dr. Udaya Halabe and Dr. John Quaranta for reviewing my thesis and participating on my examination committee. I gratefully acknowledge the financial support provided by West Virginia Department of Transportation, Division of Highways through a Graduate Research Assistantship through a research project funded through West Virginia University. I would like to thank my friends, Raj Kumar Gondle, Rupesh Gondle, Benjamin Bowes, Sumanth Gundagatti, Laura Sesack ...