Engineering Commons^™

Strength, Fracture Evolution, And Permeability Changes From Confined Brazilian Tests On Sandstone, Tyler Louis Hagengruber

Civil Engineering ETDs

This research reports on confined Brazilian strength tests and concurrent permeability testing on sandstone. The majority of the tests measured permeability during loading to failure in the confined extension region. Additional testing includes unloading and reloading cycles to detect the development of microcracks and the dependence of permeability on mixed stress conditions. Further testing characterizes fracture networks by observing porosity changes due to microcrack interactions before peak load. All tests involve 5 cm diameter disk-shaped, jacketed samples that are subjected to confining stresses while they are diametrically loaded. Specially designed end caps allow for gas flow measurements. The test configuration …

Investigation Of Subsurface Stratigraphy And Groundwater Dynamics In The Mississippi River Delta, An Li

LSU Doctoral Dissertations

The Mississippi River Delta (MRD) is socioeconomically important to the state of Louisiana and the United States. Various types of land-water system data have been collected in the MRD. However, very few efforts have been made to utilize these datasets in modeling regional stratigraphy and groundwater dynamics in the MRD, especially for the upper 50 m of the depth. In this interval of depth, the Mississippi River and surrounding interdistributary bays intensively interact with the groundwater system. The lack of knowledge in regional stratigraphy and groundwater dynamics hinder an understanding of how hydrogeological setting affects processes such as surface-groundwater interaction, …

Modeling And Simulation Of Damage In The Brazilian Indirect Tension Test Using The Finite-Discrete Element Method, Jeremiah C. Leyba

Civil Engineering ETDs

The Brazilian indirect tension test is used to investigate possible correlations between progressive damage and associated permeability changes. The test offers ease of replicability with a damage behavior known to lead to fracture openings as a tool for interpreting the indirect tensile strength of concrete and rocks. This behavior can lend insight into the nature of tensile damage and fracture progression in association with changes in permeability. The nature of these brittle materials is known to exhibit rapid failures in the Brazilian indirect tension test and require a method to retard the progression of damage for the possibility of acquiring …

Characterization And Modeling Of Asphalt Concrete For Dynamic Properties And Performances, A S M A. Rahman

Civil Engineering ETDs

The recently developed mechanistic-empirical pavement design guide (MEPDG, also known as Pavement M-E design method) uses the nationally calibrated, binder viscosity-based dynamic modulus predictive model for the design and analysis of asphalt pavements. In this study, this model is assessed for its appropriateness for asphalt-aggregate mixtures typically used in New Mexico. In essence, this study investigates the predictability issue of complex modulus of New Mexico mixes. A total of 54 Superpave mixes with different aggregate gradations, air voids, and binder grades were collected from the mixing plants and from the pavement construction sites. The loose asphalt mixtures were then compacted, …

Assessment Of Rockfall Rollout Risk Along Varying Slope Geometries Using The Rocfall And Crsp Software, Mariam S. Al E'Bayat

Masters Theses

"Most routes in mountainous areas suffer from rock falling, rolling and bouncing risk. There are many computer programs concerned with simulating the rockfall problem, and whereas they have the same purpose, they however differ in the input data that's needed to simulate the problem, and they also differ in the way of processing and kind of output.

This study used Rocfall® and the Colorado Rockfall Simulation Program (CRSP®) to simulate sixty-three models of varying slope geometry, where only the slope geometry is changed with the same material properties for both the slope and the rocks.

Both programs were fast and …

Ncma Groundwater Model Using Usgs Modflow-2005/Pest, Brian Matthew Wallace

Master's Theses

A numerical model for the NCMA aquifer complex is presented. The objective of the study is to develop a numerical groundwater model for the NCMA aquifer system to enhance the understanding of subsurface groundwater flow. Infiltration, streamflow, pumping, and return flows are implemented to characterize the aquifer complex over time. The numerical model is calibrated to municipal and monitoring well data, average monthly water balances, and hydraulic contours. Transient aquifer inflows and outflows are assessed in the results of the study and are compared to balance terms from previous studies. The 2007 Todd Engineers Study subsurface inflows and outflows generate …