In recent years, it has been discovered that some structural elements of the I-10 and I-35 corridor passing through San Antonio, Texas (San Antonio Y) are suffering from premature concrete deterioration related to alkali-silica reaction (ASR) and/or delayed ettringite formation (DEF). While there is considerable evidence of materials related distress, the degree of damage to structural capacity has not been quantified. In a comprehensive search of literature, very little research has been identified that quantifies the amount of structural damage caused by ASR and/or DEF on the load carrying capacity of structural piers. Due to the fact that this integral stretch of interstate highway sees a large volume of traffic, it is desirable to determine a method of assessing the degree of structural damage, and the necessity of taking remedial actions. The purpose of this thesis is to develop an assessment methodology which can be used by The Texas Department of Transportation (TxDOT) to evaluate the current and future integrity of structural elements in the San Antonio Y. The key steps included in the methodology are conducting a literature review on the effects of ASR and/or DEF on the structural properties of reinforced concrete, evaluating in-situ engineering properties of existing concrete, investigating the basis for the original design, and performing an experimental investigation to determine the effect of cracking on the load carrying capacity of typical SAY piers. This thesis presents the findings from this research. / text

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In-situ copper leaching at BHP Copper's San Manuel open pit mine was established in 1986. Currently, over a thousand wells on the benches of the open pit mine are simultaneously injecting and pumping sulfuric acid solutions. A large-scale reconfiguration of the well field in 1996 led to a dramatic, yet temporary, increase in copper pounds, apparently due to changes in flowpaths. While the first reconfiguration was accomplished by means of hydrologic intuition, a question arose regarding the issue of whether subsequent reconfigurations supplemented with additional smaller scale characterization could ultimately lead to increased copper production. To study this question, two fifty-well sites were selected within the in-situ leach well field. Because in-situ leaching involves the movement of fluid within the subsurface, hydrology is a natural context in which to study the process. The desire to optimize well-to-well in-situ leaching for enhanced copper recovery through the fundamental understanding of important hydrologic mechanisms is the primary motivation for this dissertation. Hydrologic testing in San Manuel is inherently challenging due to the hydraulically dynamic environment. A hydraulic cross-hole testing procedure termed "Cyclic Pulse Testing" (CPT) was used to overcome this issue. Over 100 pressure responses obtained via CPT at the two test sites were examined by means of type curve analysis. The spatially distributed hydraulic parameters were analyzed within the framework of geostatistics. The kriged heterogeneous hydraulic conductivity fields were inputted into a numerical flow and transport model to study, along with other issues, the impact heterogeneity has upon the in-situ leaching process. A number of conclusions were reached based upon the investigation of the two test sites. Comparison between single-hole and cross-hole hydraulic tests revealed the probable presence of a low permeable skin surrounding the wells. By far, the most important hydrologic mechanism controlling the in-situ leaching process in San Manuel was the massively induced hydraulic background gradient, in places, on the order of 35°. Modeling revealed insignificant differences on the sweeping efficiency of the formation between heterogeneous and homogeneous simulations. However, due to the twodimensional nature of the collected data, additional three-dimensional information may lead to a different conclusion.

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