Behavior of Model Piles in a Liquefiable Soil in Shaking Table Tests

The responses of model piles in a liquefiable ground under one- and two-dimensional shakings were studied in a physical model test using a large biaxial laminar shear box on the shaking table at the National Center for Research on Earthquake Engineering (NCREE), Taiwan. The model piles were made of stainless steel pipe and aluminum alloy pipe with an outer diameter of 101.6 mm and a wall thickness of 3.0 mm for the study of the soil-pile interactions with two kinds of stiffness of pile. Each model pile was placed in the shear box containing saturated clean fine sand. The pile tip was fixed at the bottom of the shear box to simulate the condition of a pile foundation embedded in a firm stratum. In addition, various amounts of masses were placed on the top of the piles for different conditions of superstructures. The input shakings included sinusoidal and recorded earthquake accelerations. Strain gauges and accelerometers were placed on the pile surface to obtain the behavior of the pile under shaking. The near- and far-field soil responses, including pore water pressure changes, accelerations, and settlements were also measured. The responses of the model pile and the soil-pile interactions, including the inertial and kinematic actions on the model pile, under shakings for liquefied and non-liquefied soil conditions were evaluated. The results showed that the stiffness of the soil vanished when soil liquefaction occurred. The performance of the pile foundation was affected by the relation among the dynamic characteristics of the pile and the surrounding soil, and the mass of the superstructure

Computational procedures for determining parameters in Ramberg-Osgood elastoplastic model based on modulus and damping versus strain

A computer code, RAMBO, is developed for obtaining the values of parameters in the Ramberg-Osgood elastoplastic model based on data of shear modulus and damping ratio at various shear strains. The basis and procedures for finding the parameters for the best fit of the data or relations defining modulus and damping ratios versus shear strain are given in this report. The Ramberg-Osgood relationship is rearranged so that the results can best fit data of both modulus and damping ratio. Constraints of data in the model are also discussed

Diffusion releases through one and two finite planar zones from a nuclear waste package

For a radioactive waste package emplacement in a potential repository, a partially saturated rock rubble zone may act more as a diffusive barrier than as a pathway to release. We approximate the diffusive transport from the waste packaging using one-dimensional one- and two-barrier geometries. When the effective diffusion coefficient in the first zone is several orders of magnitude lower than that in the host rock, then the two-zone geometry can be approximately by a one-zone problem, keeping only the narrow rubble zone. When the effective diffusion coefficients in the two zones are comparable, or there is an additional barrier, then a two-zone (both of finite extent) approach is adopted. We present solutions for the diffusion response in the two planar geometries for three input cases: a pulse transient input, a steady input rate, and a constant concentration at the source. The solutions have algebraic key elements allowing identification of sensitive factors. For the one-zone case, dimensionless parameters allow plotting of the family of transient response solutions on a single graph. Comparisons with several problems analyzed by others, and on problems where the one-zone and two-zone analyses should give comparable results, support verification of the method

Performance assessment model of a single waste package

PANDORA-1.1 is a system model for the mobilization and release of radionuclides from a spent nuclear fuel disposal package. Earlier processes affecting release are represented by input tables. Several groundwater contact alternatives and spent fuel constituents lead to different release-rate behaviors and controlling parameters. Rate control is provided by a product of parameters from hydrology, design, and/or geochemistry/waste form interaction parameters. The program is designed to accommodate evolving requirements such as a wider range of hydrological input values. A computerized configuration management system automates much of the change control process

A New Seismic-Geotechnical Strong Motion Approach

We have developed a new approach to estimate site-specific strong motion due to earthquakes on specific faults or source zones. It combines seismologic and geotechnical studies. It entails obtaining records of small earthquakes at the site, both at the surface and downhole in bedrock, as well as performing geotechnical dynamic site characterization. This new approach has the dual result of providing an optimized definition of the dynamic geotechnical site properties and providing calculated free-field, strong motion estimates. The procedure is demonstrated at the Painter Street Bridge site in Rio Dell, CA, for which we provide a range of surface motions corresponding to an earthquake of magnitude 7 on the subducting plate underlying this region. These calculated motions bracket the records of the Petrolia event (M = 7) measured near the site

Air-injection field tests to determine the effect of a heat cycle on the permeability of welded tuff

As part of a series of prototype tests conducted in preparation for site characterization of the potential nuclear-waste repository site at Yucca Mountain, Nevada, air-injection tests were conducted in the welded tuffs in G-Tunnel at the Nevada Test Site. The objectives were to characterize the permeability of the highly fractured tuff around a horizontal heater emplacement borehole, and to determine the effect of a heating and cooling cycle on the rock-mass permeability. Air was injected into packed-off intervals along the heater borehole. The bulk permeability of the rock adjacent to the test interval and the aperture of fractures intersecting the interval were computed from the air-flow rate, temperature, and pressure at steady state. The bulk permeability of intervals along with borehole varied from a minimum of 0.08 D to a maximum of over 144 D and the equivalent parallel-plate apertures of fractures intersecting the borehole varied from 70 to 589 {mu}m. Higher permeabilities seemed to correlate spatially with the mapped fractures. The rock was then heated for a period of 6.5 months with an electrical-resistive heater installed in the borehole. After heating, the rock was allowed to cool down to the ambient temperature. The highest borehole wall temperature measured was 242{degree}C. Air injection tests were repeated following the heating and cooling cycle, and the results showed significant increases in bulk permeability ranging from 10 to 1830% along the borehole. 8 ref., 6 figs., 3 tabs

Field air injection tests to determine the effect of a heat cycle on the permeability of welded tuff

As part of a series of prototype tests conducted in preparation for site characterization at Yucca Mountain, air-injection tests were conducted in the welded tuffs in G-Tunnel at the Nevada Test Site. The objectives were to characterize the permeability of the highly fractured tuff around a horizontal heater emplacement borehole, and to determine the effect of a heating and cooling cycle on the rock-mass permeability. Air was injected into packed-off intervals along the heater borehole. The bulk permeability of the rock adjacent to the test interval was computed from the air-flow rate, temperature, and pressure at steady state. The permeability varied from a minimum of 0.08 D to a maximum of over 144 D. Higher permeabilities seemed to correlate spatially with the mapped fractures. The rock was then heated for a period of 6.5 months with an electrical-resistive heater installed in the borehole. After heating, the rock was allowed to cool down to the ambient temperature. the highest borehole wall temperature measured was 242{degrees}C. Air injection tests were repeated following the heating and cooling cycle, and the results showed significant increases in bulk permeability ranging from 10 to 1830% along the borehole

Site characterization criteria (DOE-STD-1022-94) for natural phenomena hazards at DOE sites. Revision 1

This paper briefly summarizes requirements of site characterization for Natural Phenomena Hazards (NPH) at DOE sites. In order to comply with DOE Order 5480.28, site characterization criteria has been developed to provide site-specific information needed for development of NPH assessment criteria. Appropriate approaches are outlined to ensure that the current state-of-the-art methodologies and procedures are used in the site characterization. General and detailed site characterization requirements are provided in the areas of meteorology, hydrology, geology, seismology and geotechnical studies