This paper describes collaborative research efforts conducted between the U.S. Army Corps of Engineers (USACE) and the U.S. Department of Homeland Security (DHS). The USACE, through its U.S. Army Engineer Research and Development Center (ERDC), has focused efforts on the development of a collaborative research program to address technical gaps related to risk and blast mitigation for dams. These research efforts involve experimental and analytical tasks designed to improve blast damage prediction capabilities for dams, navigation locks, and levee systems resulting from vehicle and waterborne delivery scenarios. The outcomes from these efforts can inform USACE's priorities, which include refining the current understanding of the effects of potential attacks, the vulnerabilities and weaknesses of its critical assets to various threat conditions, and the local and regional consequences of those attacks in order to develop appropriate protective measures and recovery technologies.

It is widely recognized that full-scale dynamic testing produces a wealth of useful information in the context of seismic performance evaluation studies of concrete dams.These types of tests can be used not only to determine the main characteristics of the dynamic response of the structure, but can also provide information to assess the relative importance of interaction mechanisms involving the dam, the impounded reservoir, and the underlying foundation region.The information gathered by dynamic full-scale tests can also be used to assess the limitations of the different numerical models that could be employed to quantify the response of the system under severe seismic excitations.This report describes a research study conducted by the U.S. Army Engineer Research and Development Center consisting of a series of field tests and numerical analyses performed on Folsom Dam, California, at the request of the U.S. Army Engineer District, Sacramento.Ambient tests and forced vibration were conducted to determine the main dynamic characteristics of the dam-foundation-reservoir system.Numerical studies of the observed response behavior were performed using 2D and 3D models of the system.This report describes these experimental and modeling efforts and discusses the comparison between the critical response features derived from observed and computed results.The results from this study complement and validate the results from other previous and current technical studies conducted on Folsom Dam, and they will effectively contribute toward a more accurate assessment of the seismic performance of this critical structure.

This report presents a series of geophysical studies performed to determine the material characteristics of the foundation rock beneath the concrete gravity sections of Folsom Dam, California.The geophysical investigations were conducted to measure the values of compression-and shear-wave (P-and S-wave) propagation velocities as well as density of the foundation materials.The U.S. Army Engineer District, Sacramento, and the U.S. Army Engineer Research and Development Center agreed upon a finalized test program consisting of seismic crosshole testing and sonic

A new 10 meter diameter telescope is being constructed for deployment at the NSF South Pole research station. The telescope is designed for conducting large-area millimeter and sub-millimeter wave surveys of faint, low contrast emission, as required to map primary and secondary anisotropies in the cosmic microwave background. To achieve the required sensitivity and resolution, the telescope design employs an off-axis primary with a 10m diameter clear aperture. The full aperture and the associated optics will have a combined surface accuracy of better than 20 microns rms to allow precision operation in the submillimeter atmospheric windows. The telescope will be surrounded with a large reflecting ground screen to reduce sensitivity to thermal emission from the ground and local interference. The optics of the telescope will support a square degree field of view at 2mm wavelength and will feed a new 1000-element micro-lithographed planar bolometric array with superconducting transition-edge sensors and frequency-multiplexed readouts. The first key project will be to conduct a survey over approximately 4000 degrees for galaxy clusters using the Sunyaev-Zel'dovich Effect. This survey should find many thousands of clusters with a mass selection criteria that is remarkably uniform with redshift. Armed with redshifts obtained from optical and infrared follow-up observations, it is expected that the survey will enable significant constraints to be placed on the equation of state of the dark energy.

Detailed subsurface geological information is not available for many areas in which critical engineering decisions are required. Remedial investigations at sites with possible subsurface contamination require detailed geological information for planning monitoring well placement, depth, and installation details, and for modeling ground water flow and possible contaminant transport. The detailed geological information is also needed for subsequent remediation alternative feasibility studies. Among the information required are surficial soil thickness and variation, depths to the water table, depths to major stratigraphic interfaces, vertical and lateral heterogeneity within units or formations, and depths to the “basement.” A geophysical investigation performed at an Aberdeen Proving Ground (APG), Maryland, site demonstrates the capability of geophysical methods for contributing to a detailed subsurface geological mapping program. Seismic refraction, electrical resistivity, transient electromagnetic surface surveys and borehole geophysical logging, integrated with existing shallow borehole information, achieve the mapping objectives. Seismic refraction cross sections map the near surface stratigraphy and the water table. Electrical resistivity cross sections reveal a very complicated distribution of sandy and clayey facies in the upper 10–15 m of the subsurface; a continuous surficial (topsoil) layer correlates with the surficial layer of the seismic section and nearby boring logs. Below the surficial layer, the complicated facies distribution has resistivities ranging from 25 ohm‐m (likely clay) to several thousand ohm‐m (dry sands and/or gravels). The complexity and details of the electrical resistivity cross section correlate with boring and geophysical logs from nearby wells. The transient electromagnetic survey maps the Pleistocene‐Cretaceous boundary, the saprolite overlying the crystalline basement, and the top of the Precambrian crystalline rocks. Conducting the transient electromagnetic soundings on a grid pattern allows the construction of a 3‐D representation of subsurface geology (as represented by variations of electrical resistivity). Depths to the interpreted Pleistocene‐Cretaceous boundary are consistent with the depths from existing shallow borings at the site and other areas of the APG. Thickness and depth of the saprolitic layer and depth to top of the Precambrian rocks are consistent with generalized geologic cross sections for the APG. Average depth to top of the Precambrian rocks beneath the site is 100 m. The geologic interpretation of the geophysical models contributes not only to the site‐specific understanding of the site but to a conceptual understanding of the larger‐scale APG geology. The geologic model then contributes to site‐specific and regional hydrogeologic modeling.

A microgravity investigation was conducted in the upstream and downstream switchyards of the Wilson Dam powerplant, Florence, Alabama. The objective of the survey was the detection in the switchyard foundations of subsurface cavities or other anomalous conditions that could threaten the stability of the switchyard structures. The survey consisted of 288 gravity stations in the downstream switchyard and 347 stations in the upstream switchyard. Significant anomalous areas in the switchyards were selected on the basis of residual gravity anomaly maps. These results were prioritized and used to guide an exploratory drilling program to investigate the cause of the anomalies. Highest‐priority boring location recommendations were in negative gravity anomaly areas, since negative anomalies could be caused by actual cavities or low‐density zones that might represent incipient cavity formation. Remaining boring locations were in positive anomaly areas for verification purposes. The results of the borings confirm the presence of cavities and soft zones indicative of cavity formation.

A seismic attenuation and air overpressure study was conducted to determine the attenuation of explosion induced ground motions and air overpressures as a function of distance from shallow subsurface detonated charges, and to derive parameters to predict blast effects at distances beyond the ordinance disposal facility boundary. A total of 210 explosive shots were monitored producing 2048 time histories of ground motions recorded in the vertical, radial, and transverse directions, in addition to recording air overpressures. The data were analyzed for peak particle velocities and peak air overpressures, then plotted versus scaled range. A best fit line was determined for the data to give average, 95% non-exceedance, and upper bound predictive equations which can be used in the disposal operations to avoid damage to adjacent structures.

Abstract : The objective of the investigation was to detect and delineate anomalies indicating the locations of buried objects or disturbed zones associated with past hazardous waste burial at the DBG. The locations of these wastes are needed so they can be excavated for removal to a permanent treatment or disposal site. Electromagnetic (EM), magnetic, and ground penetrating radar (GPR) surveys were conducted at the DBG to meet this objective. Anomalies from each survey method were mapped an interpretations of their cause were tabulated.

Mill Creek Dam, near Walla Walla, Washington has experienced anomalous seepage since its first filling in 1941. Various attempts to abate and control the seepage, including construction of a concrete wall, have not been completely successful. Construction of the cutoff wall reduced the seepage by about 30 percent, from 33 cubic feet per second to 22 cubic feet per second, and downstream saturated farmland was reduced by 56 percent. However, there are indications of increased seepage pressures in a conglomerate formation in the right abutment. A comprehensive, integrated geophysics investigation of the right abutment area of the dam was conducted to detect and map anomalous conditions and assist in the evaluation of remedial measures. The geophysics program consisted of microgravity, ground penetrating radar, seismic reflection, electromagnetic conductivity, and electrical resistivity surveying. Results of the program indicate anomalous conditions extending from the reservoir area through the right abutment. The aspects of the program planning leading to technique selection and field procedures are emphasized, as well as the role of different geophysical techniques in defining the nature of anomalous condition.