Daniel W. Wilson

Bio: Daniel W. Wilson is an academic researcher from University of California, Davis. The author has contributed to research in topics: Centrifuge & Liquefaction. The author has an hindex of 18, co-authored 83 publications receiving 1906 citations. Previous affiliations of Daniel W. Wilson include California Department of Transportation & University of California, Berkeley.

Seismic Soil-Pile-Structure Interaction Experiments and Analyses

Abstract: A dynamic beam on a nonlinear Winkler foundation (or “dynamic p-y”) analysis method for analyzing seismic soil-pile-structure interaction was evaluated against the results of a series of dynamic centrifuge model tests The centrifuge tests included two different single-pile-supported structures subjected to nine different earthquake events with peak accelerations ranging from 002 to 07g The soil profile consisted of soft clay overlying dense sand Site response and dynamic p-y analyses are described Input parameters were selected based on existing engineering practices Reasonably good agreement was obtained between calculated and recorded responses for both structural models in all earthquake events Sensitivity of the results to dynamic p-y model parameters and site response calculations are evaluated These results provide experimental support for the use of dynamic p-y analysis methods in seismic soil-pile-structure interaction problems

Mechanisms of Seismically Induced Settlement of Buildings with Shallow Foundations on Liquefiable Soil

Abstract: Seismically induced settlement of buildings with shallow foundations on liquefiable soils has resulted in significant damage in recent earthquakes. Engineers still largely estimate seismic building settlement using procedures developed to calculate postliquefaction reconsolidation settlement in the free-field. A series of centrifuge experiments involving buildings situated atop a layered soil deposit have been performed to identify the mechanisms involved in liquefaction-induced building settlement. Previous studies of this problem have identified important factors including shaking intensity, the liquefiable soil's relative density and thickness, and the building's weight and width. Centrifuge test results indicate that building settlement is not proportional to the thickness of the liquefiable layer and that most of this settlement occurs during earthquake strong shaking. Building-induced shear deformations combined with localized volumetric strains during partially drained cyclic loading are the dominant mechanisms. The development of high excess pore pressures, localized drainage in response to the high transient hydraulic gradients, and earthquake-induced ratcheting of the buildings into the softened soil are important effects that should be captured in design procedures that estimate liquefaction-induced building settlement.

Observed Seismic Lateral Resistance of Liquefying Sand

Abstract: This paper presents results from a study of the dynamic response of pile foundations in liquefying sand during seismic loading. The study included a series of dynamic centrifuge tests of pile-supported structures and the back-calculation of time histories for the lateral resistance p and relative displacement y between a pile and the free-field soil. Details of the centrifuge experiments and the procedures used to back-calculate p and y time histories are described. The back-calculated p-y time histories provide a concise representation of the experimental results and can be compared to the equivalent p-y behavior predicted by soil-pile interaction analysis methods. The observed p-y behavior provides insight into the mechanisms of soil-pile interaction in liquefying sand, showing characteristics that are consistent with the undrained cyclic loading behavior of saturated sand, including the effects of relative density, cyclic degradation, pore-pressure generation, prior displacement (strain) history, and p...

Centrifuge Testing to Evaluate and Mitigate Liquefaction-Induced Building Settlement Mechanisms

Abstract: The effective application of liquefaction mitigation techniques requires an improved understanding of the development and consequences of liquefaction. Centrifuge experiments were performed to study the dominant mechanisms of seismically induced settle- ment of buildings with rigid mat foundations on thin deposits of liquefiable sand. The relative importance of key settlement mechanisms was evaluated by using mitigation techniques to minimize some of their respective contributions. The relative importance of settlement mechanisms was shown to depend on the characteristics of the earthquake motion, liquefiable soil, and building. The initiation, rate, and amount of liquefaction-induced building settlement depended greatly on the rate of ground shaking. Engineering design procedures should incorporate this important feature of earthquake shaking, which may be represented by the time rate of Arias intensity i.e., the shaking intensity rate. In these experiments, installation of an independent, in-ground, perimetrical, stiff structural wall minimized deviatoric soil deformations under the building and reduced total building settlements by approximately 50%. Use of a flexible impermeable barrier that inhibited horizontal water flow without preventing shear deformation also reduced permanent building settlements but less significantly.

Nonlinear Seismic Soil-Pile Structure Interaction:

Abstract: Analytical design tools for evaluation of soil‐pile‐structure interaction during seismic events are evaluated and modified. Several implementations of the “Beam on Nonlinear Winkler Foundation” (BNWF) method were used to predict results of centrifuge model tests of single piles in a soft clay soil profile. This paper shows that calculations from these computer codes can be sensitive to the details of the arrangement of nonlinear springs and linear viscous dashpots. Placing the linear viscous dashpots (representing radiation damping in the far field) in series with the hysteretic component of the p‐y elements (representing the nonlinear soil‐pile response in the near field) is shown to be technically preferable to a parallel arrangement of the viscous and hysteretic damping components. Preliminary centrifuge data is reasonably modeled by the numerical calculations using this implementation of damping, but additional field or physical model data are needed to fully evaluate the reliability of BNWF ...

Handbook of Chemistry and Physics

Abstract: There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Seismic Soil-Pile-Structure Interaction Experiments and Analyses

Abstract: A dynamic beam on a nonlinear Winkler foundation (or “dynamic p-y”) analysis method for analyzing seismic soil-pile-structure interaction was evaluated against the results of a series of dynamic centrifuge model tests The centrifuge tests included two different single-pile-supported structures subjected to nine different earthquake events with peak accelerations ranging from 002 to 07g The soil profile consisted of soft clay overlying dense sand Site response and dynamic p-y analyses are described Input parameters were selected based on existing engineering practices Reasonably good agreement was obtained between calculated and recorded responses for both structural models in all earthquake events Sensitivity of the results to dynamic p-y model parameters and site response calculations are evaluated These results provide experimental support for the use of dynamic p-y analysis methods in seismic soil-pile-structure interaction problems

Biogeochemical processes and geotechnical applications: progress, opportunities and challenges

Abstract: Consideration of soil as a living ecosystem offers the potential for innovative and sustainable solutions to geotechnical problems. This is a new paradigm for many in geotechnical engineering. Realising the potential of this paradigm requires a multidisciplinary approach that embraces biology and geochemistry to develop techniques for beneficial ground modification. This paper assesses the progress, opportunities, and challenges in this emerging field. Biomediated geochemical processes, which consist of a geochemical reaction regulated by subsurface microbiology, currently being explored include mineral precipitation, gas generation, biofilm formation and biopolymer generation. For each of these processes, subsurface microbial processes are employed to create an environment conducive to the desired geochemical reactions among the minerals, organic matter, pore fluids, and gases that constitute soil. Geotechnical applications currently being explored include cementation of sands to enhance bearing capacity and liquefaction resistance, sequestration of carbon, soil erosion control, groundwater flow control, and remediation of soil and groundwater impacted by metals and radionuclides. Challenges in biomediated ground modification include upscaling processes from the laboratory to the field, in situ monitoring of reactions, reaction products and properties, developing integrated biogeochemical and geotechnical models, management of treatment by-products, establishing the durability and longevity/reversibility of the process, and education of engineers and researchers.

Role of domain walls in the abnormal photovoltaic effect in BiFeO 3

Abstract: Recently, the anomalous photovoltaic (PV) effect in BiFeO3 (BFO) thin films, which resulted in open circuit voltages (Voc) considerably larger than the band gap of the material, has generated a revival of the entire field of photoferroelectrics. Here, via temperature-dependent PV studies, we prove that the bulk photovoltaic (BPV) effect, which has been studied in the past for many non-centrosymmetric materials, is at the origin of the anomalous PV effect in BFO films. Moreover, we show that irrespective of the measurement geometry, Voc as high as 50 V can be achieved by controlling the conductivity of domain walls (DW). We also show that photoconductivity of the DW is markedly higher than in the bulk of BFO.