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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Ph.D. Thesis Defense Announcement
Dr. David Frost (CEE), Dr. Sheng Dai (CEE), Dr. Polo Chau (CC), Dr. Cino Viggiani (Univ. Grenoble), Dr. Bernardo Caicedo (Univ. Andes)
Date & Time: Oct 29th - 9 am
Location: https://bluejeans.com/498975972
Complete announcement, with abstract, is attached
The exploration of the underground space is essential to the exploitation of energy resources, the foundation and design of structures and, more importantly, to the sustained development of cities both in terms of transportation and access to utilities. The urbanization and densification of the population around the globe has caused a reduction of the above-ground space, and an increased demand for urban transportation and utility systems. Such increased demand and low availability of above-ground space has highlighted the social and environmental benefits that underground construction offers, and the need for new and more efficient subsurface design methods.
Nature has created and perfected exceptional, sustainable and cost-efficient strategies to build underground cavities (e.g., worms and ants), and transportation networks (e.g., roots, leaves and fungal networks). Underground networks are global, interconnected systems, subjected to complex environmental constrains that vary in space and time. Taking inspiration from natural systems, we analyze the mechanical performance of underground structures at the scale of the cavity, and we optimize cost and resiliency of the scale of the entire network.
In the first part of the thesis, we take inspiration from biology to optimize networks that connect resources spread over a finite domain and we apply biological network models to the design of engineered systems. We first study the morphogenesis of slime mold, and we describe its behavior with transport indirect graphs. We apply slime mold underlying network deployment strategies to the optimization of fracture patterns in rock. Then, we use a leaf venation inspired algorithm to model roads and public transportation, benchmarking its performance against theoretical bounds and applying it to the design of transportation networks in the city of Atlanta.
In the second part of the thesis, we focus on the mechanical behavior of underground cavities embedded in granular soil at shallow depth, which is relevant to in-situ testing, tunneling, anchoring and arching. We focus on the mechanical behavior and failure patterns of such cavities, and we examine common assumptions used in practice to model cavity expansion. We first present the results of a comprehensive experimental study on pressurized vessels under geo-static stress. We analyze the influence of the length of the cavity, the density of the soil and the vertical surcharge load on failure mechanisms and strain patterns. We then use the finite element method (FEM) and machine learning (ML) algorithms to quantify the influence of various cavity and soil parameters and understand their influence on the behavior of the cavity. Lastly, we show an application to real design problems, using an ant colony optimization algorithm to automate and accelerate the design process of horizontal directional drills.
