Proposals to establish a manned base on the moon have necessitated the in-depth study of the engineering properties of the lunar regolith. In this investigation, the density and stress-strain-strength behavior of a lunar soil simulant in low vacuum were studied. A lunar soil simulant was produced from crushed terrestrial basalt rock and a vacuum triaxial stress device was designed, fabricated, and operated. The simulant was compacted to ultimate density, subjected to one-dimensional stress while constrained, and then subjected to triaxial states of stress. Vacuum levels ranged from 760 torr to 0.004 torr. Confining stresses considered were 0.10 MPa, 0.14 MPa, and 0.17 MPa. Low vacuum was found not to have any significant effect on the density or the stress-strain-strength behavior of the simulant as compared to results of tests at atmospheric pressure.

This thesis discusses the suitability of the box-counting method as a tool describing complex geometrical phenomena in nature by estimating their fractal dimensions, D. The study evaluated the influence of the parameters of the box counting method on the estimated fractal dimension using Koch curves of known fractal properties. It became clear that the employed size range of the applied box networks has the strongest influence on the obtained fractal dimension. A successful application of the box-counting method to generated 2-D joint patterns proved the ability of the fractal dimension to capture the influence of joint size and density on the statistical homogeneity of rock masses. Joint data from a tunnel of the Three Gorges Dam site in China was examined for potential statistical homogeneity. It was possible to find five different statistically homogeneous regions by combining the estimated fractal dimension and a visual geological evaluation of the joint maps.

This thesis describes in-situ flow tests on bentonite borehole plugs installed in granite, as well as laboratory experiments on similar plugs. Prior to sealing, the hydraulic conductivity of the boreholes is tested. These measurements, together with core logs and borehole videologs, permit the selection of suitable seal test intervals. Standard waterwell sealing bentonite products and emplacement procedures are used for borehole sealing. Transient (short-term) and steady-state (long-term) testing determines the sealing performance of the plugs (although the premature termination of the "steady state" testing precluded full data collection). Laboratory and field experiments confirm the great difficulty of obtaining accurate performance values for bentonite plugs as installed, due to the simultaneous saturation, swelling, and consolidation effects. Conventional installation of readily available seals can provide adequate borehole seals. Bentonite plugs of this type are heterogeneous and weak. Improved testing procedures and analyses are needed if actual conductivity values are to be obtained in a reasonable testing time.

<p> As the final line of defense against flood, it is important to protect the levees against erosion. The erodibility potential of levee material has an influence on scour generation in levees. In this investigation, the effect of various soil parameters including compaction ratio, plasticity index and saturation ratio on levee erosion due to overtopping is considered. For this purpose, physical models of a typical levee on the banks of Mississippi river with a scale of 1:20 were constructed in the laboratory using a variety of soil types including Non-Plastic Silt, Low-Plastic Clay, and the combination of these two to achieve various soil characteristics for levee material. A sharp wooden plate, which was embedded vertically in the crest of the levee, represented the floodwall. </p><p> During the lab tests different geometric and hydraulic parameters of the levee were monitored to identify scour development. In addition, the erodibility of the levee materials was determined using an Erosion Function Apparatus (EFA). The results of EFA tests were compared to physical model test results to explore and discuss the vulnerability of levee systems to erosion with change in levee material characteristics. The results were also compared to levees without floodwalls. The effect of wall inclination was also considered and analyzed. The effect of each soil parameter is discussed in detail on erosion characteristics measured by EFA and levee tests. </p><p> These tests and comparisons resulted in the observation that EFA yields lower erosion rates comparing to the simulated levee tests. Increasing the compaction rate and plasticity index improves the erodibility of levee material while increasing in saturation ratio, causes the erodibility of soil to increase. Wall Inclination does not have a significant effect on scour generation while levees without floodwalls show comparatively lower erosion rates.</p>

This thesis develops a new computation of the objective function and gradient for normal moveout-based differential semblance (DS). The DS principle underlies a class of algorithms for seismic velocity analysis. The simplest variant of DS is based on a drastic approximation to the scattering of waves, called "normal moveout" (NMO) in the seismic literature. This simple NMO-driven DS algorithm is very fast relative to other variants based on more faithful approximations to wave physics, but nonetheless accurate enough to be used to process field data. A recent implementation of NMO-based DS demonstrated these capabilities, but it also exhibited numerical irregularity which may have affected the stability of its velocity estimates. My alternative approach avoids interpolation noise that existed in previous work and so results in more stable numerical optimization.

Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3671. Adviser: Scott Olson. Includes bibliographical references (leaves 266-306) Available on microfilm from Pro Quest Information and Learning.

<p> Since its completion in 1910, the Chicago Sanitary and Ship Canal (CSSC) has become a pathway for invasive species (and potentially Asian carp) to reach the Great Lakes. Currently, an electric barrier is used to prevent Asian carp migration through the canal, but the need for a secondary method is necessary, especially when the electric barrier undergoes maintenance. The underwater Asian carp &ldquo;cannon&rdquo; (water gun) provides such a method. Analysis of the ground movement produced by an 80 in³ water gun in the CSSC was performed in order to establish any potential for damage to the either the canal or structures built along the canal. Ground movement was collected using 3-component geophones on both the land surface and in boreholes. The peak particle velocities (PPVs) were analyzed to determine if damage would be caused to structures located along the canal. Vector sum velocity ground movement along the canal wall was as high as 0.28 in/s (7.11 mm/s), which is much lower than the United States Bureau of Mines (USBM) ground vibration damage threshold of 0.75 in/s (19.1 mm/s), causing no potential for damage to structures along the canal wall. The dominant frequency of ground motion produced by the water gun is primarily above 40 Hz, so the wave energy should attenuate fairly quickly away from the canal wall, with little disturbance to structures further from the wall.</p>

In this study, a two dimensional finite element model is developed to analyze the effects of seepage and traction on slope stability. The finite element model was used to determine the failure mechanisms associated with tractive and seepage induced failures. Limit equilibrium models were then developed to model both seepage and tractive erosion based on the failure mechanisms indicated by the finite element model. A conceptual model to qualitatively predict the effects of changes in flow regime on the stability of sandbars within recirculating zones was also developed. The finite element model uses Biot's coupled stress-pore water pressure theory to simulate the effects of transient loading conditions on the stresses, phreatic surface variations and displacements within a soil mass. The finite element model's simulations of various events recorded on Grand Canyon sandbars compared favorably with field data. A limit equilibrium model to simulate seepage effects on homogeneous slopes was developed. It is shown that at the seepage surface, the magnitude and direction of the seepage vector are uniquely related and are not independent variables as was previously assumed in the literature. Seepage parallel to the slope is shown to result in the minimum stable seepage slope. Static liquefaction is shown to be possible for a range of seepage directions, depending on the unit weight of the soil. The conceptual model relates the qualitative effects of changes in the flow regime to the geometry of sandbars within recirculating zones. The effects of changes in discharge on the characteristics of the recirculating zones are related to sandbar stability. The predictions of the conceptual model compared favorably with the observed behavior of Grand Canyon sandbars.

Coupling effects between thermal, hydraulic, chemical and mechanical (THCM) processes for rock materials are one of major issues in Geological engineering, Civil engineering, Hydrology, Petroleum engineering, and Environmental engineering. In all of these fields, at least two mechanisms of THCM coupling are considered. For an example, thermal, hydraulic, and mechanical coupling effects are important in Geological engineering and Civil engineering. The THM coupling produces effects on underground structures, since the underground structures are under influences of geothermal gradient, groundwater, gravitational stresses, and tectonic forces. In particular, underground repository of high-level nuclear waste involves all four of the THCM coupling processes. Thermo-hydro-mechanical coupling model for fractured rock media has been developed based on micromechanical fracture model [Kemeny 1991, Kemeny & Cook 1987]. The THM coupling model is able to simulate time- and rate-dependent fracture propagation on rock materials, and quantify characteristics of damage by extensile and shear fracture growth. The THM coupling model can also simulate coupled thermal effects on underground structures such as high-level nuclear waste repository. The results of thermo-mechanical coupling model are used in conducting a risk analysis on the structures. In addition, the THM coupling model is able to investigate variations of fluid flow and hydraulic characteristics on rock materials by measuring coupled anisotropic permeability. Later, effects of chemical coupling on rock materials are investigated and modified in the THM coupling model in order to develop a thermo-hydro-chemo-mechanical coupling model on fractured rocks. The THCM coupling model is compared with thermal, hydraulic, chemical, and mechanical coupling tests conducted at the University of Arizona. The comparison provides a reasonable prediction for the THCM coupling tests on various rock materials. Finally, the THCM coupling model for fractured rocks simulates the underground nuclear waste storage in Yucca Mountain, Nevada, and conducted performance and risk analysis on the repository.

Fluid flow modeling in fractured rocks is a complicated and important research and application topic in many fields such as geological, hydrogeological, environmental and petroleum engineering. Commonly used methods based on equivalent continuum assumption for fluid flow modeling can generally be applied directly to the porous geological media, but have limited applicability when the geological medium is dominated by fractures. It often happens that only limited time, cost, hydrogeological data and computer resources are available in solving a practical problem of the fluid flow modeling in fractured rocks. Therefore, it is a challenge, but necessary, to investigate the hydraulic behaviors and propose new approaches, procedures, and methodologies to build a reliable fluid flow model for fractured rocks with limited available related data. The general concepts on fluid flow modeling in fractured rocks are introduced firstly and the different ways to treat major and minor fractures in 2-D and 3-D discrete fracture fluid flow modeling are propounded. The author has investigated the relations between the hydraulic behaviors and fracture geometry parameters and found out the effect of fracture parameters on the Representative Elementary Volume (REV) for the fracture systems with statistically distributed fracture geometry parameters including the size, orientation and location. Further, a systemic procedure for fluid flow modeling in fractured rocks in two-dimensional domain is suggested and demonstrated through a 2-D case study for groundwater resources evaluation. Six 3-D conceptual linear pipe discrete fracture fluid flow models which focus on the utilization of fracture information are proposed to simulate packer or pumping tests conducted in fractured rock masses. These models can reflect channel flow in fractures, simplify and minimize the complexity of fluid flow in fractures, save computer resources and increase the possibility to solve a field problem at large scales, and implement a discrete fracture fluid flow model easily. Finally, the author has developed a practicable systemic approach to determine the REV for hydraulic properties and then the hydraulic conductivity tensor for the REV in fractured rocks using single well packer test results. These procedures are illustrated through a 3-D case study by implementing the proposed fluid flow models.