Civil and Environmental Engineering Commons^™

Hybrid: The Future Of Construction Meetings In The Digital Age, Nicholas G. Orozco

Construction Management

Over the last few years, many construction companies have had to upheave traditional methods of construction meetings to adapt to rapidly changing COVID-19 safety and regulation protocols. For many, this has meant taking common in-person meetings (OAC, pre-construction, and design) and shifting them virtual. As companies continue to move forward in a post-pandemic climate, the question of whether they will continue with virtual meetings or revert to in-person meetings still lingers in the air. To get a better read on the future of construction meetings post-pandemic, a survey was sent to determine what most people prefer. A total of 21 …

Spatiotemporal Variations Of Precipitation And Climate-Resilient Structure Design In Virginia, Xiaomin Yang

Civil & Environmental Engineering Theses & Dissertations

How to consider effects of climate change on the design and management of hydrology related infrastructure is crucial but remains a challenge for sustaining resilient society. To address this challenge, existing hydrologic design procedures may need to be revised and/or redeveloped to take into account the precipitation non-stationarity resulting from climate change. Using the state of Virginia as a testbed and advanced statistical techniques such as nonparametric test, spatial autocorrelation, linear regression, distribution fitting, and spatial interpolation, this dissertation developed an innovative framework to detect the historical spatiotemporal variations of various precipitation characteristics, namely maximum precipitation intensity, precipitation amount, simple …

Data-Driven Operational And Safety Analysis Of Emerging Shared Electric Scooter Systems, Qingyu Ma

Computational Modeling & Simulation Engineering Theses & Dissertations

The rapid rise of shared electric scooter (E-Scooter) systems offers many urban areas a new micro-mobility solution. The portable and flexible characteristics have made E-Scooters a competitive mode for short-distance trips. Compared to other modes such as bikes, E-Scooters allow riders to freely ride on different facilities such as streets, sidewalks, and bike lanes. However, sharing lanes with vehicles and other users tends to cause safety issues for riding E-Scooters. Conventional methods are often not applicable for analyzing such safety issues because well-archived historical crash records are not commonly available for emerging E-Scooters.

Perceiving the growth of such a micro-mobility …

To A More Sustainable Construction Method For Electrically Conductive Heated Pavement Systems, Mohammad Anis

Theses and Dissertations

Snow and ice damage to the pavement in the United States, particularly in colder regions, costs the US economy millions of dollars each year. Conventional methods for keeping snow off roads after heavy snowfall are judged prohibitively expensive. As a result, an alternative solution is required to reduce costs while also improving pavement resiliency. An electrically heated pavement system (EHPS) has been regarded as a viable alternative to older approaches in recent years. The majority of earlier research concentrated on improving the conductivity characteristics of paving materials. On the other hand, this study takes a different approach by focusing on …

The Skeletal Structure Of Hot Mix Asphalt And The Effects Of Fiber Additives, Samantha A. Avila

Theses and Dissertations

Hot mix asphalt (HMA) has proven to be successful in providing a proper paving surface for transportation services throughout the world. Asphalt pavement could be altered as the gradation of the mixture is adjusted. For instance, mixtures could vary from Dense Graded (DG) that contain a fairly even percentage of all aggregate size allowing for a more compact fit to Stone Matrix Asphalt (SMA) where the coarse aggregate compromise the main skeleton while fine aggregate fills the voids. This study investigates the effects of fibers and skeletal structures on mechanical properties of HMA. Two types of fiber additives are tested …

Life-Cycle Cost Analysis Of The Efficient Water Fixtures And Electric Appliances Used To Minimize Water And Energy Consumption In Homes In The U.S, Miranda N. Garcia

Theses and Dissertations

Consumer interest in incorporating sustainability and efficient appliances into daily life has been growing in the past several years. While reducing their environmental impact may be a draw to some, by making the switch to water- and energy-efficient appliances many homeowners are enticed by the promise of long-term savings on utility bills. Programs such as WaterSense and Energy Star not only offer certified efficient appliances and fixtures, but they may also certify water- and energy-efficient homes. Additionally, the United States Green Building Council (USGBC) offers the LEED program (Leadership in Energy and Environmental Design) which certifies homes in a similar …

Integrated Processing Of Municipal Solid Waste For Maximizing Waste Reduction, Carbon Recovery And Fuel Production, Kameron J. King

Civil & Environmental Engineering Theses & Dissertations

Nationally and internationally, waste generation is increasing and along with it negative environmental impacts. Many people think waste ends at disposal; however, environmental impacts have already begun. Unfortunately, 50% of waste ends up in a landfill which is the third largest source of human related methane emissions and a leading cause of global climate change. This study investigated a novel waste management strategy in hopes of mitigating negative environmental effects caused by conventional waste management practices. The novelty of the study lies in the development of an integrated method of hydrothermal carbonization and an anaerobic digestion (HTC + AD) process …

Assessment Of The Hydrograv® Adapt Variable Height Secondary Clarifier Inlet At Hrsd Nansemond Treatment Plant, Matthew Poe

Civil & Environmental Engineering Theses & Dissertations

The Hampton Roads Sanitation District (HRSD) recently completed the first North American and center driven installation of the Hydrograv® Adapt Variable Height Secondary Clarifier Inlet (Adapt) at HRSD’s Nansemond Treatment Plant. This is a variable height inlet structure designed to decrease clarifier effluent turbidity and maintain low turbidity during high flow events. Low turbidity is achieved by feeding the secondary clarifier influent within the solids blanket during dry weather conditions and lifting the inlet structure during wet weather conditions to avoid disrupting the blanket. The Adapt clarifier was monitored alongside an identical fixed inlet clarifier to assess performance. Both clarifiers …

The Impact Of Wastewater Chemistry And Flow Characteristics On Hydrogen Sulfide Concentration, Mohsina Muhammed Sherief

Theses

Hydrogen sulfide (H₂S) is a naturally occurring, highly toxic gas that is formed from the decomposition of sulfur compounds. At low concentrations, H₂S is an irritant for the eyes, respiratory and gastrointestinal tract. At higher H₂S concentrations, it produces neurological impairment with dizziness, headache, and loss of consciousness. Mortality was reported to reach 6 percent following exposure to elevated concentrations. H₂S is generated in different industrial processes. In wastewater collection and treatment plants, H₂S is a common source of concrete and metal corrosion that has resulted in huge economic loss. …

Microplastics Fouling And Interaction With Polymeric Membranes: A Review, Mitra Golgoli, Mehdi H. Khiadani, Abdellah Shafieian, Tushar K. Sen, Y. Hartanto, M. L. Johns, Masoumeh Zargar

Research outputs 2014 to 2021

The emergence and accumulation of microplastics (MPs) in various aquatic environments have recently raised significant concerns. Wastewater treatment plants (WWTPs) have been identified as one of the major sources of MPs discharge to the environment, implying a substantial need to improve advanced techniques for more efficient removal of MPs. Polymeric membranes have been proven effective in MPs removal. However, fouling is the main drawback of membrane processes and MPs can foul the membranes due to their small size and specific surface properties. Hence, it is important to investigate the impacts of MPs on membrane fouling to develop efficient membrane-based techniques …

Effects Of The Soil Spatial Variability On Pipelines, Jose Luis Espinosa Mendez

Electronic Thesis and Dissertation Repository

Pipelines are the safest and most efficient way to transport large volumes of oil and gas from extraction fields, to refineries, industry and home consumption. Extensively used to transport fluids over long distances, pipelines may pass through terrain features exposed to geohazards. The performance of buried pipelines in areas subjected to ground displacements constitute a criterion for design, assessment and management of gas pipelines, to ensure public, environment and property safety in a cost-effective manner. Modern surveying and sampling techniques allow for better geotechnical characterization of ground movements and the variability of the soil properties with confidence. The statistical data …

Guidelines For Designing The Overhead Transmission Tower Foundations Adjacent To Cohesionless Slopes, Meshel Q. Alkahtani

Electronic Thesis and Dissertation Repository

Foundations supporting electrical transmission line towers are subjected to oblique loading due to tower own weight along with wind loading. Due to land limitation and linear alignment of transmission lines, many power transmission towers are situated in sand near sloping grounds and proper evaluation of their foundation performance is essential for the safety and reliability of the critical power transmission lines. There is currently no guidance available on the behaviour of transmission towers foundations constructed near slopes. Thus, the primary objectives of this study are to evaluate the response of transmission tower foundations in cohesionless sloping grounds and investigate the …

Naturally Occurring Van Der Waals Heterostructure Lengenbachite With Strong In-Plane Structural And Optical Anisotropy, Arindam Dasgupta, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Lengenbachite is a naturally occurring layered mineral formed with alternating stacks of two constituent PbS-like and M₂S₃-like two-dimensional (2D) material layers due to the phase segregation process during the formation. Here, we demonstrate to achieve van der Waals (vdW) heterostructures of lengenbachite down to a few layer-pair thickness by mechanical exfoliation of bulk lengenbachite mineral. The incommensurability between the constituent isotropic 2D material layers makes the formed vdW heterostructure exhibit strong in-plane structural anisotropy, which leads to highly anisotropic optical responses in lengenbachite thin flakes, including anisotropic Raman scattering, linear dichroism, and anisotropic third-harmonic generation. Moreover, …

General Analytical Solution For Consolidation Of Sand-Drained Ground Considering The Vacuum Loading Process And The Time-Dependent Surcharge Loading, Wei-An Lin, Wen-Hao Jiang, Liang-Tong Zhan

Rock and Soil Mechanics

Based on Barron’s equal strain consolidation theory, the consolidation governing equation of sand-drained ground under vacuum combined surcharge preloading is derived, and a general analytical solution is obtained, which considers the vacuum loading process, the time-dependent surcharge loading, the characteristics of the vacuum pressure decreasing along with the depth and radial direction, and the smear effect of vertical drains and the vertical flow. The correctness of the analytical solution proposed in this paper is verified by comparing the degenerate analytical solution with the existing analytical solution and the finite difference solution. Based on the analytical solution, the consolidation behaviors of …

Macro And Micro Coupling Analysis Of Cone Penetration Test: Methodology And Application, Chang-Hong Wang, Dao-Fei Tang, Kun Wang, Zhao-Xin Wu

Rock and Soil Mechanics

No abstract provided.

A Constitutive Model Considering Post-Liquefaction Deformation Based On The Logarithmic Skeleton Curve, Qing Dong, Zheng-Hua Zhou, Jie Su, Xiao-Jun Li, Bing Hao

Rock and Soil Mechanics

Most of the constitutive model for liquefaction analysis cannot simulate the large post-liquefaction deformation of saturated sand, and there is little research on the nonlinear time-domain large deformation constitutive relationships suitable for seismic response analysis of saturated sand sites. In this paper, a feasible, simple and applicable large deformation constitutive model for time domain analysis is proposed through experimental analysis and theoretical research. The post-liquefaction stress-strain relationships of liquefied sand are obtained based on the undrained cyclic triaxial test data, then loading-reloading rules of large post-liquefaction deformation are proposed. Combined with the effective stress constitutive model based on logarithmic skeleton …

Effects Of Cyclic Loading Directions On Liquefaction Characteristics Of Saturated Coral Sand, Kang Liu, Guo-Xing Chen, Qi Wu, Wei-Jia Ma, You Qin

Rock and Soil Mechanics

The large scale construction of both military and civil infrastructures located in Nansha reefs and offshore marine areas, South China Sea, has raised the seismic safety a challenging issue for the projects in the region. The influences of fines content (FC) on the liquefaction characteristics of saturated terrestrial quartz sands have been extensively studied, but the corresponding research on saturated coral sands in reclaimed coral islands is less involved. Using the GDS hollow cylinder torsion shear apparatus, a series of isotropically consolidated undrained cyclic tests have been performed on saturated coral sand sampled from the Nansha Islands, South China Sea. …

Study On Bearing Capacity Of Permeable Pipe Pile By Field Optical Fiber Monitoring, Jing Wang, Tao Xiao, Hong-Hu Zhu, Guo-Xiong Mei, Zheng-Yuan Liu, Guang-Qing Wei

Rock and Soil Mechanics

Permeable pipe piles are set in the soft soil foundation to accelerate the dissipation rate of excess pore water pressure induced by pile driving and then to accelerate the consolidation of soil around the pile. At present, there are many studies, including model tests and numerical simulation, on the bearing capacity and permeability performance of permeable pipe piles. However, few field tests have been conducted to deeply study the time effect of bearing capacity and load transfer law of permeable pipe piles. Based on the fiber Bragg grating (FBG) technology, the static load tests were carried out to study the …

Analysis Of Laterally-Loaded Piles Embedded In Multi-Layered Soils Using Efficient Finite-Element Method, Hai-Peng Zhao, Xue-You Li, Jian-Hong Wan, Xiang-Zhi Zheng, Si-Wei Liu

Rock and Soil Mechanics

Mechanical analysis of laterally-loaded piles embedded in multi-layered soils is a critical step in design. Traditional finite-element method may have deficiency in accuracy and efficiency when applied to analyze this problem. An efficient finite-element method is proposed in this paper. A “pile element” that adopts the distributed “soil springs” along the element length to reflect the nonlinear behaviors of the pile-soil interactions is developed in this method. The dominant feature of the pile element is the direct integration of soil properties into the element formulation, namely, a pile element comprises both the pile and soil properties. The pile element formulation …

Response Analysis Of Residual Soil Slope Considering Crack Development Under Drying−Wetting Cycles, Yue Liu, Dong-Xia Chen, Hui Wang, Jia-Jing Yu

Rock and Soil Mechanics

In order to study the response of granite residual soil slope with cracks under different number of drying-wetting cycles (D-W cycles), model test was carried out and the crack width expansion index was quantified by investigating the crack images. Based on the direct shear test, the calculation formulas of soil strength degradation and crack depth were developed. Then, the model test and the numerical simulation results were compared to analyze the response of the residual soil slope considering crack extension. The results showed that the fractures width expansion in residual soil under D-W cycles followed the Logistic model, and there …