Coupled Hydrological-Geotechnical Model for Determinine Bearing Capacity and Elastic Settlement of Foundations

This dissertation presents a coupled hydrological-geotechnical framework to investigate the performance of shallow and deep foundations under hydrological events such as heavy rainfall and drought. The variation in performance of foundation, interface between the structure and ground surface, is caused by the uncertainties associated with not only the geotechnical parameters but also the hydrological parameters that include intensity and duration of hydrological events and water table depth. The impact of such hydrological events significantly alters the performance of foundations by changing the soil strength and stiffness parameters of subsurface soil which may lead to foundation failures. Such failures can cause damage to the supporting structure. Therefore, to better understand the performance of geotechnical systems under different hydrological events and also to build sustainable and resilient infrastructure systems, the design of geotechnical systems should be carried out in a coupled hydrological-geotechnical manner considering the site-specific geotechnical and hydrological parameters. To this end, a numerical framework is developed based on the partially saturated soil mechanics principles and applied to a number of sites in the United States to show the impacts of hydrological events in the performance of shallow and deep foundations. In this framework, the one-dimensional Richards’ equation is numerically solved to compute the spatial and temporal variation of the degree of saturation and matric suction in subsurface soil due to the site-specific rainfall, evapotranspiration, and water table depth as model boundary conditions. Then, the critical settlement and bearing capacity of foundations (as critical design values) are calculated using the average degree of saturation and matric suction within the foundation influence zone. It is worth mentioning that two different design methodologies based on the probabilistic analysis and single extreme hydrological cycle are considered in the proposed framework to have a better assessment of foundation performance. The results show that the hydrological parameters have a significant impact on the performance of shallow and deep foundations, and in general, they improve the predicted foundation design values obtained from conventional methods in terms of the settlement and bearing capacity. The proposed method can be used as a decision-making tool for selecting the suitable design values of foundations in engineering practice

Visualizing and Analyzing Fluid Flow through Porous Medium

This CI project aims to understand and visualize how fluid flows through various porous materials and how the mesoscopic material properties influence flow process. Porous material is ubiquitous in nature and engineering and appears in many forms including sands, foams, and shredded tires. Understanding how fluid flows through various porous materials has important engineering implications. One example application that motivates this project is contaminant transport problem in porous materials: if there is an oil leakage from underground pipe line or if there is polluted underground water, how and where will the contaminate moves within the soil mass and what measures could be taken to guide and/or stop the flow contaminates. In this project, student will design and construct simple experimental devices to visualize and analyze flow process through various porous materials (geological materials such as soil, and man-made materials such as glass beads). Students will also have opportunities to learn basic theory behind the physical phenomenon and use computer tools (such as Matlab) to model and assist in understanding such process