A basis for developing a general approach to solve geotechnical engineering problems through dynamic finite element analysis of nonlinear porous media is presented. A new series of constitutive models named here as δ* series are developed under the general hierarchical single surface (HISS) modeling approach, to include the behavior of, saturated normally consolidated and overconsolidated clay, under drained or undrained, static and cyclic loading conditions. Algorithms for determination of material parameters for these models from laboratory models are also developed. Constitutive parameters for Sabine Clay are obtained using triaxial test results from undisturbed samples and the model is verified by back predicting the laboratory behavior of this clay. Sensitivity analyses for all the material parameters have been also carried out. Efficient and reliable algorithms for calculating strain increments for given stress increments and vice versa are developed. All the models in the δ* series are implemented in the finite element program POROUS which is based on the theory of dynamics of nonlinear porous media. Here a modular approach is used to facilitate easy modification of all the functions associated with these models (yield function, potential function, hardening function and interpolation functions). Complete test procedure for field load tests on two pile segments (3 inch and 1.72 inch) are numerically simulated and compared with field measurements. Initial stresses before pile driving are estimated using results of s self boring pressuremeter test on the site. Strain distributions just after pile driving are evaluated using the strain path method. The effective stress distribution is obtained by integrating constitutive equations for given strain paths. Corresponding total stresses and pore pressure distributions are obtained using the computer program POROUS. Consolidation after pile driving and all the static and cyclic tests followed are also simulated using the program POROUS. The predicted normalized pore pressure dissipation curve matches the field behavior. This analysis provides good predictions of shear transfer from which the pile capacity can be evaluated. Even though the variation of pore pressure during a cycle is not matched exactly, the accumulation of pore pressures are predicted well. The demonstrated ability of dynamic finite element analysis of nonlinear porous media, to simulate slow consolidation and cyclic load tests provides a basis for developing a general approach for solving geotechnical engineering problems.

Soil nail walls are a form of mechanical earth stabilization for cut situations. They consist of the introduction of passive inclusions (nails) into soil cut lifts. These nailed lifts are then tied together with a structural facing (usually shotcrete) . The wall lifts are constructed incrementally from the top of cut down. Soil nail walls are being recognized as having potential for large cost savings over other alternatives. The increasing need to provide high capacity roadways in restricted rights of way under structures such as bridges will require increasing use of techniques such as combined soil nail and piling walls. The Swift Delta Soil Nail wall required installing nails between some of the existing pipe piling on the Oregon Slough Bridge. This raised questions of whether the piling would undergo internal stress changes due to the nail wall construction. Thus, it was considered necessary to understand the soil nail wall structure interaction in relation to the existing pile supported abutment. The purpose of this study was to investigate the Swift Delta Wall using finite element (FE) modeling techniques. Valuable data were available from the instrumentation of the swift Delta Wall. These data were compared with the results of the FE modeling. This study attempts to answer the following two questions: 1. Is there potential for the introduction of new bending stresses to the existing piling? 2. Is the soil nail wall system influenced by the presence of the piling? A general purpose FE code called ABAQUS was used to perform both linear and non-linear analyses. The analyses showed that the piling definitely underwent some stress changes. In addition they also indicated that piling influence resulted in lower nail stresses. Comparison of measured data to predicted behavior showed good agreement in wall face deflection but inconsistent agreement in nail stresses. This demonstrated the difficulty of modeling a soil nail due to the many variables resulting from nail installation.

Due to the similarity between the geometry and full displacement installation method of a cone penetrometer and displacement pile, the axial capacity of displacement piles is often assessed using data from a cone penetration test (CPT). As there are many more factors influencing pile axial capacity than affecting CPT cone resistance, there are a wide range of CPT-based empirical design methods in use. These methods have various levels of predictive success, which usually depends upon the soil conditions, pile geometry, pile installation method, and time between installations and loading. An improved understanding of the basis and reliability of respective design methods is essential to improve the quality of predictions in the absence of site specific load test data. This thesis explores the influence of soil state and drainage conditions on piezocone penetration test (CPTU) tip resistance (qc) and penetration pore pressures (u2). For cone penetration testing identified as 'drained', factors influencing the correlation between cone tip resistance and displacement pile shaft friction in sand are investigated through (i) a review of previous research and the performance of existing design methods; (ii) centrifuge studies of piles of differing widths with measurements of local lateral stress; (iii) field tension tests at different times between installation and loading for uninstrumented driven piles with different diameters and end conditions; and (iv) field tension tests at different times between installation and loading on closed ended strain gauged jacked segmented model piles with different installation sequences. CPTU qc and u2 are primarily controlled by soil state and drainage conditions, with effective stress strength parameters and soil stiffness also influencing the measurements. The primary mechanisms identified to control the correlation between cone tip resistance and shaft friction on displacement piles are identified as; (i) the initial increase in radial stress due to soil displaced during installation of a pile; (ii) different levels of soil displacement induced by open, closed, and partially plugged piles; (iii) reduction in radial stress behind the pile tip; (iv) additional reduction in radial stress with continued pile penetration (friction fatigue); (v) changes in radial stress during loading; (vi) constant volume interface friction angle between soil and steel; and (vii) changes in the effects of the above mentioned mechanisms with time between installation and loading. The relative effect of each of these factors is investigated in this thesis.

Deep foundations, including driven piles, are used to support vertical loads of structures and applied lateral forces. Many pile supported structures, including bridges, are subjected to large lateral loads in the form of wind, wave, seismic, and traffic impact loads. In many practical situations, structures subjected to lateral loading are located near or in excavated and fill slopes or embankments. Full-scale research to examine the effects of soil slope on lateral pile capacity is limited. The purpose of this study is to examine the effects on lateral capacity of piles located in or near cohesionless soil slopes. A full-scale lateral load testing program was undertaken on pipe piles in a cohesionless soil at Oregon State University. Five piles were tested near a 2H:1V test slope and located between 0D to 8D behind the slope crest, where D is the pile diameter. Two vertical baseline piles and three battered piles were also tested in level ground conditions. The cohesionless backfill soil was a well-graded material with a fines content of less than 10% and a relative compaction of 95%, meeting the Caltrans specification for structural backfill. Data collected from the instrumented piles was used to back calculate p-y curves, load-displacement curves, reduction factors, and load resistance ratios for each pile. The effects of slope on lateral pile capacity are insignificant at displacements of less than 2.0 inches for piles located 2D and further from the crest. For pile located at 4D or greater from the slope crest, the effect of slope is insignificant on p-y curves. A simplified p-multiplier design procedure derived from back-calculated p-y curves is proposed to account for the effects of soil slope. Comparisons of the full-scale results were made using proposed recommendations from the available literature. Lateral resistance ratios obtained by computer, centrifuge, and small scale-models tend to be conservative and overestimate the effects of slope on lateral capacities. Standard cohesionless p-y curve methods slightly over predict the soil resistance at very low displacements but significantly under predict the ultimate soil resistance. Available reduction factors from the literature, or p-multipliers, are slightly conservative and compare well with the back-calculated p-y curves from this study. / Graduation date: 2012

This dissertation presents the results of a research effort conducted to better understand the seismic performance and analysis of pile-supported wharves. Given the limited number of well-documented field case histories, the seismic performance of pile-supported wharves has been poorly quantified, and the analysis methods commonly employed in engineering practice have generally not been validated. Field case histories documenting the seismic performance of pile-supported wharves commonly contain only limited information, such as approximations of wharf and embankment deformations and peak ground surface accelerations. In order to supplement the field data, five centrifuge models were dynamically tested, with each model containing close to 100 instruments monitoring pile bending moments, excess pore pressures, displacements, and accelerations. The combined field and model database was used to develop seismic performance relationships between permanent lateral deformations, maximum and residual bending moments and peak ground surface displacements. Key issues such as the seismic performance of batter piles, the development of large moments at depth, and the need to account for permanent lateral deformations for high levels of shaking, even for very stable geometries, are discussed. The field data and model studies were also used to validate two geotechnical seismic performance analysis methods: 1) the limit-equilibrium based rigid, sliding block (Newmark) method, and 2) an advanced finite-difference effective stress based numerical model (FLAC). Favorable predictions were generally obtained for both methods, yet there was a large variability in the results predicted using the rigid, sliding block method. The numerical model predicted the permanent deformations, pore pressure generation, and accelerations fairly well, however, pile bending moments were poorly predicted. The results of this research clearly highlighted the need for analysis validation studies, and note the uncertainty and variability inherent in the seismic performance of complex structures. The lack of adequate validation may lead to an over-confidence and false sense of security in the results of the seismic analysis methods. This dissertation specifically addresses pile-supported wharves, yet the results presented herein are applicable to other pile-supported structures located near, or on, slopes adjacent to the waterfront, such as: bridge abutments, railroad trestles, and pile-supported buildings near open slopes. Performance and analysis issues common to all of these structures are addressed, such as: liquefiable soils, lateral pile response in horizontal and sloping soils, the lateral behavior of piles in rock fill, and global slope stability, as well as the general observed seismic behavior. / Graduation date: 2004

University of Macau / Faculty of Science and Technology / Department of Civil and Environmental Engineering

A macroelement is developed for soil-structure interaction analyses of piles in liquefiable soils, which captures efficiently the fundamental mechanisms of saturated granular soil behavior. The mechanical model comprises a nonlinear Winkler-type model that accounts for soil resistance acting along the circumference of the pile, and a coupled viscous damper that simulates changes in radiation damping with increasing material non-linearity. Three-dimensional (3D) finite element (FE) simulations are conducted for a pile in radially homogeneous soil to identify the critical parameters governing the response. The identified parameters, i.e., hydraulic conductivity, loading rate of dynamic loading, dilation angle and liquefaction potential are then expressed in dimensionless form. Next, the macroelement parameters are calibrated as a function of the soil properties and the effective stress. A semi-empirical approach that accounts for the effects of soil-structure interaction on pore pressure generation in the vicinity of pile is used to detect the onset of liquefaction. The predictions are compared with field data obtained using blast induced liquefaction and centrifuge tests and found to be in good agreement. Finally, the macroelement formulation is extended to account for coupling in both lateral directions. FEM simulations indicate that response assuming no coupling between the two horizontal directions for biaxial loading tends to overestimate the soil resistance and fails to capture features like 'apparent negative stiffness', 'strain hardening' and 'rounded corners'.

published_or_final_version / Applied Geosciences / Master / Master of Science

The motivation for this study is to create a scaled laboratory model of a steel construction pile being driven by an impact hammer, which can provide controlled data to aid understanding and development of a structural acoustics numerical model simulating full-scale impact pile driving. The scaled model is approximately thirty times shorter than a typical 30-meter long Cast-in-Shell-Steel (CISS) pile. The relationship between the impact force, structural vibrations, and radiated sound field is analyzed. The time-domain acoustic intensity in the radial direction is found to be predominately negative immediately following excitation by the impact force. Analysis of the radial intensity shows that during the hammer strike, there is a net flow of energy from the structure into the water; however, because the structure and water are acoustically coupled a significant portion of the energy immediately flows back into the cylinder following hammer impact. This fluid-structure interaction results in a highly damped acoustic pulse in the water that propagates to the far field. In addition, the frequency spectra of the impact force, model pile wall acceleration in the radial direction in air and water, and underwater acoustic pressure are analyzed to find transfer functions between these variables. The transfer function between impact force and sound pressure is of particular interest because it can be used to calculate the system response for any other applied hammer force. This transfer function analysis has potential applications in mitigating noise generated by impact pile driving.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-06-29T15:20:33Z No. of bitstreams: 2 Dissertação - Sergio Giovanni Espinosa Villafuerte - 2016.pdf: 5665796 bytes, checksum: 265521cbc03e90b213938b3b6896dc46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-06-30T11:14:18Z (GMT) No. of bitstreams: 2 Dissertação - Sergio Giovanni Espinosa Villafuerte - 2016.pdf: 5665796 bytes, checksum: 265521cbc03e90b213938b3b6896dc46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-06-30T11:14:18Z (GMT). No. of bitstreams: 2 Dissertação - Sergio Giovanni Espinosa Villafuerte - 2016.pdf: 5665796 bytes, checksum: 265521cbc03e90b213938b3b6896dc46 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-08 / Pantaneiro genetic sheep group are native to the Pantanal Biome, in the Midwest region of Brazil, which is characterized by the production of meat. They are usually created under pasture, and the lambs usually finished in confinement. But should be considered sustainable and intensive finishing systems, adapted to the region. The aim of this study was to evaluate four finishing systems, including the productive performance and economic results as profitability indicators. Were used 54 lambs, 24 males and 30 females, wormed at weaning, with initial weight of 16.70 kg, with a mean age of 74 ± 9 days. Finishing systems were; Feedlot with corn silage (Zea mays) (CS) as roughage; Feedlot with mix corn silage and Pigeon pea (Cajanus cajan cv Mandarin) as roughage (CPS); Integration Crop-Livestock (ICL) grazing Brachiaria brizantha cv. BRS Piatã grass with Pigeon pea (Cajanus cajan cv Mandarin) in succession to mixed cultivation; stockpiled pasture (SP) with Brachiaria brizantha cv. BRS Piatã grass. All treatments the animals received energy-protein concentrate supplementation (16% CP and 82% TDN) equivalent to 2% of body weight. The experimental design was completely randomized in a factorial design, with four finishing systems and two sexes. The variables were final weight (FW) and average daily gain (ADG), and economic evaluation. Finishing systems under CS and ICL, obtained better productive performance not differing significantly from the CPS, which in turn did not differ statistically from SP. However, the economic evaluation demonstrated that the ICL and CPS systems were more profitable in finishing lambs. The pasture system formed in Integration Crop-Livestock with supplement of 2% of body weight, proved to be the most appropriate for the Midwest region in the finishing of Pantaneiro lambs in the dry season. / Ovinos Pantaneiros são nativos do Bioma Pantanal, na região Centro Oeste do Brasil, que tem como característica a produção de carne. Normalmente são criados em pastagens, sendo os cordeiros terminados geralmente no confinamento. Porém deve-se considerar sistemas de terminação sustentáveis e intensivos, adaptados a região. Neste sentido foram avaliados quatro sistemas de terminação, incluindo o desempenho produtivo e a eficiência econômica e indicadores de rentabilidade. Foram utilizados 54 cordeiros, 24 machos e 30 fêmeas, desverminados no desmame, com peso inicial de 16,70 kg, com idade média de 74±9 dias. Os sistemas de terminação avaliados foram o confinamento a base de volumoso de silagem de milho (Zea mays) (M); confinamento a base de volumoso de silagem de milho mais guandú (Cajanus cajan cv Mandarim) (MG); Integração Lavoura Pecuária (ILP) pastejo em Brachiaria brizantha cv. BRS Piatã mais guandú (Cajanus cajan cv Mandarim) em sucessão ao cultivo consorciado; pasto vedado (V) com Brachiaria brizantha cv. BRS Piatã. Em todos tratamentos os animais receberam suplementação de concentrado energético-proteico (16% PB e 82% NDT) equivalente a 2% do peso vivo. O delineamento experimental utilizado foi o inteiramente casualizado em esquema fatorial, sendo 4 sistemas de terminação e 2 sexos. As variáveis avaliadas foram, peso final (PVF) e ganho de peso médio diário (GMD), e a projeção econômica. Os sistemas de terminação sob M e ILP, obtiveram melhores desempenhos produtivos, não diferindo significativamente do MG, que por sua vez não diferiu estatisticamente do V. No entanto, na avaliação econômica ficou demonstrado que os sistemas ILP e MG foram mais rentáveis na terminação de cordeiros. O sistema a pasto formado em Integração Lavoura-Pecuária, com suplementação correspondente a 2% do peso corporal, mostrou-se o mais indicado para a região Centro-Oeste na terminação de cordeiros Pantaneiros no período seco.