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Piles
Kinds of Piles Terms modified by Piles Selected AbstractsAlternative Spaces of the "Argentinazo"ANTIPODE, Issue 5 2004Peter North The ongoing instability in Argentina that emerged from the December 2001 uprising in Buenos Aires (the "Argentinazo") has been one of the highest profile examples in recent years of reaction to the economic "disciplining" of a country. For enthusiasts, this reaction has been resistance, an upsurge against neoliberalisation by people conscious of what was happening and with alternative conceptions of how things should be (Aufheben 2003; Carrera and Cotarelo 2003; Dinerstein 2002; Galeano 2002; Harman 2002; "IM" 2002; Klein 2003a, 2003b; MAS 2002; Ollier 2003). Subaltern resistances such as those developed by Argentines have been the subject of much geographical writing on resistance in recent years (Castells 1997; Leyshon, Lee and Williams 2003; Pile and Keith 1997; Sharp et al 2000). This paper addresses the range of actions, or "action repertoire"(Tarrow 1998:20,21), of the Argentinazo to examine the extent to which alternative material and discursive "convergence spaces"(Routledge 2003) of political engagement emerged both as resistance to, and articulating a coherent alternative to, neoliberalism. [source] Three-dimensional finite element analyses of passive pile behaviourINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2006L. F. Miao Abstract Piles may be subjected to lateral soil pressures as a result of lateral soil movements from nearby construction-related activities such as embankment construction or excavation operations. Three-dimensional finite element analyses have been carried out to investigate the response of a single pile when subjected to lateral soil movements. The pile and the soil were modelled using 20-node quadrilateral brick elements with reduced integration. For compatibility between the soil,pile interface elements, 27-node quadrilateral brick elements with reduced integration were used to model the soil around the pile adjacent to the soil,pile interface. A Mohr,Coulomb elastic,plastic constitutive model with large-strain mode was assumed for the soil. The analyses indicate that the behaviour of the pile was significantly influenced by the pile flexibility, the magnitude of soil movement, the pile head boundary conditions, the shape of the soil movement profile and the thickness of the moving soil mass. Reasonable agreement is found between some existing published solutions and those developed herein. Copyright © 2005 John Wiley & Sons, Ltd. [source] Spontaneous Vegetation on Overburden Piles in the Coal Basin of Santa Catarina, BrazilRESTORATION ECOLOGY, Issue 3 2008Robson Dos Santos Abstract The objective of this work was to select indigenous vegetal species for restoration programs aiming at the regeneration of ombrophilous dense forest. Thirty-five spoil piles located in the county of Sideropolis, Santa Catarina, that received overburden disposal for 39 years (1950,1989) were selected for study because they exhibited remarkable spontaneous regrowth of trees compared to surrounding spoil piles. Floristic inventory covered the whole area of the 35 piles, whereas survey on phytosociology and natural regeneration studies were conducted in 70 plots distributed along the 35 piles. Floristic inventory recorded 83 species from 28 botanical families. Herbaceous terricolous plants constituted the predominant species (47.0%), followed by shrubs (26.5%), trees (19.3%), and vines (7.2%). Results from surveys on phytosociology and natural regeneration, focused on shrubs and trees, recorded incipient ecological succession. In addition, the most adapted species recorded on the overburden piles, as ranked by index of natural regeneration (RNT) plus importance value index (IVI), were as follows: Clethra scabra (RNT = 23.93%; IVI = 17.28%), Myrsine coriacea (RNT = 20.93%, IVI = 11.26%), Eupatorium intermedium (RNT = 7.56%, IVI = 0.40%), Miconia ligustroides (RNT = 5.84%, IVI = 2.37%), Ossaea amygdaloides (RNT = 3.84%, IVI = 1.30%), Tibouchina sellowiana (RNT = 3.29%, IVI = 1.94%), Eup. inulaefolium (RNT = 2.65%, IVI = 0.80%), and Baccharis dracunculifolia (RNT = 2.28%; IVI = 0.56%). High values of IVI and RNT exhibited by the exotic species Eucalyptus saligna (IVI = 21.73%, RNT = 51.41%) indicated strong competition between exotic and indigenous species. Severe chemical (acidic pH and lack of nutrients) and physical (coarse substrate and slope angle of 40,50°) characteristics displayed by the overburden piles constituted limitations to floristic diversity and size of indigenous trees, indicating the need for substrate reclamation prior to forest restoration. [source] Tubular Piles , Buckling Design in a Complex SituationBAUTECHNIK, Issue 8 2008Anton Hübner Dr.-Ing. No abstract is available for this article. [source] Pigment cell distributions in different tissues of the zebrafish, with special reference to the striped pigment patternDEVELOPMENTAL DYNAMICS, Issue 2 2005Masashi Hirata Abstract The orderly pigment pattern of zebrafish (Danio rerio) is a good model system for studying how spatial patterns form in animals. Recent molecular genetic studies have shown that interactions between the pigment cells play major roles in pattern formation. In the present study, we performed comparative transmission electron microscopy of pigment cells, in order to clarify the structural interactions of pigment cells in tissues with and without a striped pattern. In patterned tissues, pigment cells were distributed as a one-cell-thick sheet. The layer order of the sheets is always kept strictly. In tissues without a striped pattern, the layer order was often disturbed or the cells were distributed in a scattered, double-sheeted, or an accumulated pile. Our observations suggest that the underlying mechanism that controls the vertical order of the pigment cells is related to that controlling the stripe pattern. Developmental Dynamics 234:293,300, 2005. © 2005 Wiley-Liss, Inc. [source] Origin and palaeo-environments of calcareous sediments in the Moshaweng dry valley, southeast BotswanaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2002S. Ringrose Abstract Quaternary sedimentation in the Moshaweng dry valley of southeastern Botswana is evaluated on the basis of geomorphological evolution and sedimentological analyses. Stratigraphic evidence reveals an upper surface (1095 m) containing abundant sil-calcrete, an intermediate surface (1085 m) in which sil-calcrete underlies nodular calcrete and lower (1075 m) surface in which sil-calcrete and nodular calcrete are interbedded. This subdivision is reflected in the geochemical composition of the sediments which show an overall trend of decreasing SiO2 content (and increasing CaCO3 content) with depth from the highest to the lowest surface levels. The calcretes and sil-calcretes represent modifications of pre-existing detrital Kalahari Group sand and basal Kalahari pebbles which thinned over a Karoo bedrock high. Modification took place during wet periods when abundant Ca++ -rich groundwater flowed along the structurally aligned valley system. With the onset of drier conditions, water table fluctuations led to the precipitation of nodular calcretes in the phreatic layer to a depth of about 20 m. A major geochemical change resulted in the preferential silicification of the nodular calcrete deposits. Conditions for silica mobilization may be related to drying-induced salinity and in situ geochemical differentiation brought about by pebble dissociation towards the top of the sediment pile. As calcretization and valley formation progressed to lower levels, silica release took place on a diminishing scale. Thermoluminescence dating infers a mid-Pleistocene age for sil-calcrete formation suggesting that valley evolution and original calcrete precipitation are much older. Late stage dissolution of CaCO3 from pre-existing surface calcretes or sil-calcretes led to the formation of pedogenic case-hardened deposits during a time of reduced flow through the Moshaweng system possibly during the upper or late Pleistocene. Copyright © 2002 John Wiley & Sons, Ltd. [source] Dynamic stiffness of deep foundations with inclined pilesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2010L. A. Padrón Abstract The influence of inclined piles on the dynamic response of deep foundations and superstructures is still not well understood and needs further research. For this reason, impedance functions of deep foundations with inclined piles, obtained numerically from a boundary element,finite element coupling model, are provided in this paper. More precisely, vertical, horizontal, rocking and horizontal,rocking crossed dynamic stiffness and damping functions of single inclined piles and 2 × 2 and 3 × 3 pile groups with battered elements are presented in a set of plots. The soil is assumed to be a homogeneous viscoelastic isotropic half-space and the piles are modeled as elastic compressible Euler,Bernoulli beams. The results for different pile group configurations, pile,soil stiffness ratios and rake angles are presented. Copyright © 2010 John Wiley & Sons, Ltd. [source] A model for the 3D kinematic interaction analysis of pile groups in layered soilsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2009Francesca Dezi Abstract The paper presents a numerical model for the analysis of the soil,structure kinematic interaction of single piles and pile groups embedded in layered soil deposits during seismic actions. A finite element model is considered for the pile group and the soil is assumed to be a Winkler-type medium. The pile,soil,pile interaction and the radiation problem are accounted for by means of elastodynamic Green's functions. Condensation of the problem permits a consistent and straightforward derivation of both the impedance functions and the foundation input motion, which are necessary to perform the inertial soil,structure interaction analyses. The model proposed allows calculating the internal forces induced by soil,pile and pile-to-pile interactions. Comparisons with data available in literature are made to study the convergence and validate the model. An application to a realistic pile foundation is given to demonstrate the potential of the model to catch the dynamic behaviour of the soil,foundation system and the stress resultants in each pile. Copyright © 2009 John Wiley & Sons, Ltd. [source] Three-dimensional behavior of a spherical self-centering precast prestressed pile isolatorEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2009Rosita Jünemann Abstract A 3D analytical formulation of a precast prestressed pile (PPP) seismic isolator with top and bottom spherical rolling kinematic constraints is proposed. The PPP isolator was initially conceived as a low-cost seismic isolation (and foundation) system for housing units of low-income people. Since these structures are usually located at sites with poor soil conditions, the PPP isolator also works as a foundation pile by connecting the superstructure with more competent soil layers. The non-holonomic nature of the rolling constraint is dealt with by a structural formulation. The proposed 3D formulation is validated by numerical results obtained from a previously proposed formulation for the 2D problem, and a contact finite element model in ANSYS (www.ansys.com). Other issues associated with the dynamic response of isolated structures with the PPP are also examined, such as expected response reductions, variation in the axial force of the central prestressed cable, and torsional response amplifications. Finally, guidelines to estimate the actual 3D response using 2D analysis results are investigated. Copyright © 2009 John Wiley & Sons, Ltd. [source] Cyclic behavior of laterally loaded concrete piles embedded into cohesive soilEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 1 2008Rabin Tuladhar Abstract Modern seismic design codes stipulate that the response analysis should be conducted by considering the complete structural system including superstructure, foundation, and ground. However, for the development of seismic response analysis method for a complete structural system, it is first imperative to clarify the behavior of the soil and piles during earthquakes. In this study, full-scale monotonic and reversed cyclic lateral loading tests were carried out on concrete piles embedded into the ground. The test piles were hollow, precast, prestressed concrete piles with an outer diameter of 300,mm and a thickness of 60,mm. The test piles were 26,m long. Three-dimensional (3D) finite element analysis was then performed to study the behavior of the experimental specimens analytically. The study revealed that the lateral load-carrying capacity of the piles degrades when subjected to cyclic loading compared with monotonic loading. The effect of the use of an interface element between the soil and pile surface in the analysis was also investigated. With proper consideration of the constitutive models of soil and pile, an interface element between the pile surface and the soil, and the degradation of soil stiffness under cyclic loading, a 3D analysis was found to simulate well the actual behavior of pile and soil. Copyright © 2007 John Wiley & Sons, Ltd. [source] Soil,pile,structure interaction under SH wave excitationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 3 2003K. K. Koo Abstract A continuum model for the interaction analysis of a fully coupled soil,pile,structure system under seismic excitation is presented in this paper. Only horizontal shaking induced by harmonic SH waves is considered so that the soil,pile,structure system is under anti-plane deformation. The soil mass, pile and superstructure were all considered as elastic with hysteretic damping, while geometrically both pile and structures were simplified as a beam model. Buildings of various heights in Hong Kong designed to resist wind load were analysed using the present model. It was discovered that the acceleration of the piled-structures at ground level can, in general, be larger than that of a free-field shaking of the soil site, depending on the excitation frequency. For typical piled-structures in Hong Kong, the amplification factor of shaking at the ground level does not show simple trends with the number of storeys of the superstructure, the thickness and the stiffness of soil, and the stiffness of the superstructure if number of storeys is fixed. The effect of pile stiffness on the amplification factor of shaking is, however, insignificant. Thus, simply increasing the pile size or the superstructure stiffness does not necessarily improve the seismic resistance of the soil,pile,structure system; on the contrary, it may lead to excessive amplification of shaking for the whole system. Copyright © 2003 John Wiley & Sons, Ltd. [source] Ignition studies of cerium nitrate treated towelsFIRE AND MATERIALS, Issue 3 2006C. L. Beyler Abstract This study evaluated the ignitability of cotton towel material saturated with an oxidizer solution of 0.5 N cerium nitrate in 2 N nitric acid. Four types of ignition testing were performed in this work: self-heating oven tests, hot object ignition tests, radiative smoldering ignition tests, and piloted flaming ignition/burning rate tests. Results indicate that cerium nitrate significantly enhances the ignitability of the towels. Self-heating properties of cerium nitrate treated towels were measured using the standard constant temperature oven method described by Bowes. Based upon these self-heating properties, self-heating is not a hazard for storage scenarios other than bulk storage (depths of several meters) of cerium nitrate treated towels at room temperature. Surface ignition of hot objects was observed for object temperatures as low as 250°C placed upon room temperature cerium nitrate treated towels. Ignition for hot objects buried within a pile of towels occurred for object temperatures as low as 230°C. Radiant heating tests of cerium nitrate treated towels showed initiation of smolder at heat fluxes as low as 3 kW/m2 at surface temperatures as low as 175°C. This compares with ordinary cellulosic materials that require 7,8 kW/m2 heat fluxes and temperatures of 250°C. All four scenarios demonstrate enhanced ignitability and burning rates of cerium nitrate treated towels. Copyright © 2005 John Wiley & Sons, Ltd. [source] Biogeochemical changes induced in uranium mining waste pile samples by uranyl nitrate treatments under anaerobic conditionsGEOBIOLOGY, Issue 3 2009A. GEISSLER Response of the subsurface soil bacterial community of a uranium mining waste pile to treatments with uranyl nitrate over different periods of time was studied under anaerobic conditions. The fate of the added U(VI) without supplementation with electron donors was investigated as well. By using 16S rRNA gene retrieval, we demonstrated that incubation with uranyl nitrate for 4 weeks resulted in a strong reduction in and even disappearance of some of the most predominant bacterial groups of the original sample. Instead, a strong proliferation of denitrifying and uranium-resistant populations of Rahnella spp. from Gammaproteobacteria and of Firmicutes occurred. After longer incubations for 14 weeks with uranyl nitrate, bacterial diversity increased and populations intrinsic to the untreated samples such as Bacteroidetes and Deltaproteobacteria propagated and replaced the above-mentioned uranium-resistant groups. This indicated that U(VI) was immobilized. Mössbauer spectroscopic analysis revealed an increased Fe(III) reduction by increasing the incubation time from four to 14 weeks. This result signified that Fe(III) was used as an electron acceptor by the bacterial community established at the later stages of the treatment. X-ray absorption spectroscopic analysis demonstrated that no detectable amounts of U(VI) were reduced to U(IV) in the time frames of the performed experiments. The reason for this observation is possibly due to the low level of electron donors in the studied oligotrophic environment. Time-resolved laser-induced fluorescence spectroscopic analysis demonstrated that most of the added U(VI) was bound by organic or inorganic phosphate phases both of biotic origin. [source] Tectonics and quaternary evolution of the Northern Apennines watershed area (upper course of Arno and Tiber rivers, Italy)GEOLOGICAL JOURNAL, Issue 1 2009Marco Bonini Abstract This work examines the connection between Quaternary tectonics and erosion/incision processes in the primary Tuscan-Romagna watershed of the Northern Apennines, which essentially coincides with the topographic culmination of the Nero Unit structural ridge. Tectonic and geomorphic information were collected in the area where this ridge is crossed by the upper Tiber River course forming a deep gorge. Structural analysis and field mapping have revealed that the region experienced polyphase tectonics with superposed thrust folding events identifiable both at the map and mesoscopic scales. Hinterland-SSW-verging thrusts and thrust-related folds deformed the whole thrust pile during the latest deformation phase. Backthrusts/backfolds controlled the development of intermountain basins nearby the main watershed during the Early Pleistocene and seemingly deformed, in the Tiber gorge, a low-relief landscape developed in the Early Pleistocene (ca. 1.1,Ma). Successively, the upper Tiber River course area and Apennines axial zone underwent a generalized uplift, which is manifested by the deep incision of palaeo-morphologies. This proposed sequence of events correlates well with the major geodynamic change of the Apennines revealed by an acceleration of uplift rates in the Middle,Late Pleistocene. This latter event may also correlate with increased rates of river incision recorded in Europe as a consequence of uplift and/or climate change. Copyright © 2008 John Wiley & Sons, Ltd. [source] A constrained 2D gravity model of the Sebastián Vizcaíno Basin, Baja California Sur, MexicoGEOPHYSICAL PROSPECTING, Issue 6 2005J. García-Abdeslem ABSTRACT The subsurface geometry of the Sebastián Vizcaíno Basin is obtained from the 2D inversion of gravity data, constrained by a density-versus-depth relationship derived from an oil exploration deep hole. The basin accumulated a thick pile of marine sediments that evolved in the fore-arc region of the compressive margin prevalent along western North America during Mesozoic and Tertiary times. Our interpretation indicates that the sedimentary infill in the Sebastián Vizcaíno Basin reaches a maximum thickness of about 4 km at the centre of a relatively symmetric basin. At the location of the Suaro-1 hole, the depth to the basement derived from this work agrees with the drilled interface between calcareous and volcaniclastic members of the Alisitos Formation. A sensitivity analysis strongly suggests that the assumed density function leads to a nearly unique solution of the inverse problem. [source] Response evaluation of axially loaded fixed-head pile groups in clayey soilsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 17 2009Emilios M. Comodromos Abstract The aim of this paper is to investigate the interaction between the piles in a group with a rigid head and correlate the response of a group of piles to that of a single pile. For this purpose, a computationally intensive study using 3-D nonlinear numerical analysis was carried out for different pile group arrangements in clayey soils. The responses of the groups of piles were compared with that of a single pile and the variation of the settlement amplification factor Ra was then quantified. The influence of the number of piles, the spacing, and the settlement level on the group response is discussed. A previously proposed relationship for predicting the response of a pile group, based on its configuration and the response of a single pile, has been modified to extend its applicability for any pile spacing. The modified relationship provides a reasonable prediction for various group configurations in clayey soils. Copyright © 2009 John Wiley & Sons, Ltd. [source] Numerical analysis of the response of battered piles to inclined pullout loadsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 10 2009Hussein Mroueh Abstract This paper presents a three-dimensional finite element analysis of the response of battered piles to the combined lateral and vertical pullout loads. Analyses are carried out using an elastoplastic constitutive law based on the non-associated Mohr,Coulomb criterion. The influence of the contact condition at the pile,soil interface is also investigated. Analyses show that the load's inclination with regard to the pile's axis affects both the lateral and axial response of the battered piles. Analyses also show that the pullout capacity of battered piles is affected by the pile's inclination regarding the vertical axis as well as the load's inclination regarding the pile's axis. The investigation of the influence of the contact condition at the soil,pile interface shows that the possibility of sliding at the soil,pile interface affects the response of battered piles subjected to loads with low inclination regarding the pile's axis. Copyright © 2008 John Wiley & Sons, Ltd. [source] Vertical stress distributions around batter piles driven in cross-anisotropic mediaINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2009Cheng-Der Wang Abstract This work presents analytical solutions to compute the vertical stresses for a cross-anisotropic half-space due to various loading types by batter piles. The loading types are an embedded point load for an end-bearing pile, uniform skin friction, and linear variation of skin friction for a friction pile. The cross-anisotropic planes are parallel to the horizontal ground surface. The proposed solutions can be obtained by utilizing Wang and Liao's solutions for a horizontal and vertical point load acting in the interior of a cross-anisotropic medium. The derived cross-anisotropic solutions using a limiting approach are in perfect agreement with the isotropic solutions of Ramiah and Chickanagappa with the consideration of pile inclination. Additionally, the present solutions are identical to the cross-anisotropic solutions by Wang for the batter angle equals to 0. The influential factors in yielded solutions include the type and degree of geomaterial anisotropy, pile inclination, and distinct loading types. An example is illustrated to clarify the effect of aforementioned factors on the vertical stresses. The parametric results reveal that the stresses considering the geomaterial anisotropy and pile batter differ from those of previous isotropic and cross-anisotropic solutions. Hence, it is imperative to take the pile inclination into account when piles are required to transmit both the axial and lateral loads in the cross-anisotropic media. Copyright © 2008 John Wiley & Sons, Ltd. [source] Vertical dynamic response of pile in a radially heterogeneous soil layerINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2009D. Y. Yang Abstract An analysis of a pile vertical response considering soil inhomogeneity in the radial direction under dynamic loads is presented. The solution technique is based on a three-dimensional axisymmetric model, which includes the consideration of the vertical displacement of the soil. The soil domain is subdivided into a number of annular vertical zones, and the continuity of the displacements and stresses are imposed at both the interface of pile,soil and the interfaces of adjacent soil zones to establish the dynamic equilibrium equations of the pile,soil interaction. Then, the equations of each soil zone and of the pile are solved one by one to obtain the analytical and semi-analytical dynamic responses at the top of the pile in the frequency domain and time domain. Parametric studies have been performed to examine the influence of soil parameters' variations in the radial direction caused by the construction effect on the dynamic responses of pile. The results of the studies have been summarized and presented in figures to illustrate the influences of the soil parameters as they change radially. The effect of the radius of the disturbed soil zone caused by construction is also studied in this paper. Copyright © 2008 John Wiley & Sons, Ltd. [source] Nonlinear response of laterally loaded piles and pile groupsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2009Wei Dong Guo Abstract In spite of extensive studies on laterally loaded piles carried out over years, none of them offers an expedite approach as to gaining the nonlinear response and its associated depth of mobilization of limiting force along each pile in a group. To serve such a need, elastic,plastic solutions for free-head, laterally loaded piles were developed recently by the author. They allow the response to be readily computed from elastic state right up to failure, by assigning a series of slip depths, and a limiting force profile. In this paper, equivalent solutions for fixed-head (FixH) single piles were developed. They are subsequently extended to cater for response of pile groups by incorporating p -multipliers. The newly established solutions were substantiated by existing numerical solutions for piles and pile groups. They offer satisfactory prediction of the nonlinear response of all the 6 single piles and 24 pile groups investigated so far after properly considering the impact of semi-FixH restraints. They also offer the extent to ultimate state of pile groups via the evaluated slip depths. The study allows ad hoc guidelines to be established for determining input parameters for the solutions. The solutions are tailored for routine prediction of the nonlinear interaction of laterally loaded FixH piles and capped pile groups. Copyright © 2008 John Wiley & Sons, Ltd. [source] Lateral load distributions on grouped piles from dynamic pile-to-pile interaction factorsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 2 2009Der-Wen Chang Abstract The load distributions of the grouped piles under lateral loads acting from one side of the pile cap could be approximately modeled using the elasticity equations with the assumptions that the underground structure is rigid enough to sustain the loads, and only small deformations of the soils are yielded. Variations of the soil,pile interactions along the depths are therefore negligible for simplicity. This paper presents the analytical modeling using the dynamic pile-to-pile interaction factors for 2,×,2 and 2,×,3 grouped piles. The results were found comparative with the experimental and numerical results of other studies. Similar to others' findings, it was shown that the leading pile could carry more static loads than the trailing pile does. For the piles in the perpendicular direction with the static load, the loads would distribute symmetrically with the centerline whereas the middle pile always sustains the smallest load. For steady-state loads with operating frequencies up to 30 Hz, the pile load distributions would vary significantly with the frequencies. It is interesting to know that designing the pile foundation needs to be cautioned for steady-state vibrations as they are a problem of machine foundation. However, for transient loads or any harmonic loads acting upon relatively higher frequencies, the pile loads could be regarded as uniformly distributed. It is hoped that the numerical results of this paper will be helpful in the design practice of pile foundation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Analysis of soil,pile,structure interaction in a two-layer ground during earthquakes considering liquefactionINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2008C. W. Lu Abstract This study is conducted with a numerical method to investigate the seismic behaviour among certain soils, single piles, and a structure. A series of numerical simulations of the seismic behaviour of a single-pile foundation constructed in a two-layer ground is carried out. Various sandy soils, namely, dense sand, medium dense sand, reclaimed soil, and loose sand, are employed for the upper layer, while one type of clayey soil is used for the lower layer. The results reveal that when a structure is built in a non-liquefiable ground, an amplification of the seismic waves is seen on the ground surface and in the upper structure, and large bending moments are generated at the pile heads. When a structure is built in a liquefiable ground, a de-amplification of the seismic waves is seen on the ground surface and in the upper structure, and large bending moments are generated firstly at the pile heads and then in the lower segment at the boundary between the soil layers when liquefaction takes place. Copyright © 2007 John Wiley & Sons, Ltd. [source] Analysis of laterally loaded piles with rectangular cross sections embedded in layered soilINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2008D. Basu Abstract An analysis is developed to determine the response of laterally loaded rectangular piles in layered elastic media. The differential equations governing the displacements of the pile,soil system are derived using variational principles. Closed-form solutions of pile deflection, the slope of the deflected curve, the bending moment and the shear force profiles can be obtained by this method for the entire pile length. The input parameters needed for the analysis are the pile geometry and the elastic constants of the soil and pile. The new analysis allows insights into the lateral load response of square, rectangular and circular piles and how they compare. Copyright © 2007 John Wiley & Sons, Ltd. [source] Skin friction features of drilled CIP piles in sand from pile segment analysisINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2008Sungjune Lee Abstract Numerical pile segment analysis is conducted in this study with an advanced soil model to investigate the skin friction behaviour of a drilled Cast-In-Place (CIP) pile installed in sand. Although the interface between the sand and pile is considered rough, thin elements adjacent to the pile are used to include effects of localized shear. Unit weights of fluid concrete and accompanied changes in stress are considered as the effects of pile installation. Changes in effective stresses are the most prominent effect due to pile installation with a change in direction of the major principal stress from the vertical to the radial direction. Shear behaviour of the sand at the interface during the early shear stage is related to the contractive tendency of the sand at small strain levels. Changes in the stress field around the pile with little changes in volumetric strain take place during the early shear stage. Stress redistributions during the early shear stage depend on the direction of the major principal stress before shear. Results of the pile segment analyses for drilled CIP piles show good agreement with design methods. Parametric studies are used to characterize the effects of sand density and pile diameter on the skin friction behaviour of drilled CIP piles. Copyright © 2007 John Wiley & Sons, Ltd. [source] Surface displacements due to batter piles driven in cross-anisotropic mediaINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 2 2008Cheng-Der Wang Abstract This article derives the closed-form solutions for estimating the vertical surface displacements of cross-anisotropic media due to various loading types of batter piles. The loading types include an embedded point load for an end-bearing pile, uniform skin friction, and linear variation of skin friction for a friction pile. The planes of cross-anisotropy are assumed to be parallel to the horizontal ground surface. The proposed solutions are never mentioned in literature and can be developed from Wang and Liao's solutions for a horizontal and vertical point load embedded in the cross-anisotropic half-space. The present solutions are identical with Wang's solutions when batter angle equals to 0°. In addition, the solutions indicate that the surface displacements in cross-anisotropic media are influenced by the type and degree of material anisotropy, angle of inclination, and loading types. An illustrative example is given at the end of this article to investigate the effect of the type and degree of soil anisotropy (E/E,, G,/E,, and ,/,,), pile inclination (,), and different loading types (a point load, a uniform skin friction, and a linear variation of skin friction) on vertical surface displacements. Results show that the displacements accounted for pile batter are quite different from those estimated from plumb piles, both driven in cross-anisotropic media. Copyright © 2007 John Wiley & Sons, Ltd. [source] Poroelastic model for pile,soil interaction in a half-space porous medium due to seismic wavesINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 1 2008Jian-Fei Lu Abstract In this paper, frequency domain dynamic response of a pile embedded in a half-space porous medium and subjected to P, SV seismic waves is investigated. According to the fictitious pile methodology, the problem is decomposed into an extended poroelastic half-space and a fictitious pile. The extended porous half-space is described by Biot's theory, while the fictitious pile is treated as a bar and a beam and described by the conventional 1-D structure vibration theory. Using the Hankel transformation method, the fundamental solutions for a half-space porous medium subjected to a vertical or a horizontal circular patch load are established. Based on the obtained fundamental solutions and free wave fields, the second kind of Fredholm integral equations describing the vertical and the horizontal interaction between the pile and the poroelastic half-space are established. Solution of the integral equations yields the dynamic response of the pile to plane P, SV waves. Numerical results show the parameters of the porous medium, the pile and incident waves have direct influences on the dynamic response of the pile,half-space system. Significant differences between conventional single-phase elastic model and the poroelastic model for the surrounding medium of the pile are found. Copyright © 2007 John Wiley & Sons, Ltd. [source] A modulus-multiplier approach for non-linear analysis of laterally loaded pile groupsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 9 2007Chia-Cheng Fan Abstract A modulus-multiplier approach, which applies a reduction factor to the modulus of single pile p,y curves to account for the group effect, is presented for analysing the response of each individual pile in a laterally loaded pile group with any geometric arrangement based on non-linear pile,soil,pile interaction. The pile,soil,pile interaction is conducted using a 3D non-linear finite element approach. The interaction effect between piles under various loading directions is investigated in this paper. Group effects can be neglected at a pile spacing of 9 times the pile diameter for piles along the direction of the lateral load and at a pile spacing of 6 times the pile diameter for piles normal to the direction of loading. The modulus multipliers for a pair of piles are developed as a function of pile spacing for departure angle of 0, 90, and 180sup>/sup> with respect to the loading direction. The procedure proposed for computing the response of any individual pile within a pile group is verified using two well-documented full-scale pile load tests. Copyright © 2006 John Wiley & Sons, Ltd. [source] Experimental and numerical investigations of the behaviour of a heat exchanger pileINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 8 2006Lyesse Laloui Abstract The geothermal use of concrete geostructures (piles, walls and slabs) is an environmentally friendly way of cooling and heating buildings. With such geothermal structures, it is possible to transfer energy from the ground to fluid-filled pipes cast in concrete and then to building environments. To improve the knowledge in the field of geothermal structures, the behaviour of a pile subjected to thermo-mechanical loads is studied in situ. The aim is to study the increased loads on pile due to thermal effects. The maximum thermal increment applied to the pile is on the order of 21°C and the mechanical load reached 1300 kN. Coupled multi-physical finite element modelling is carried out to simulate the observed experimental results. It is shown that the numerical model is able to reproduce the most significant thermo-mechanical effects. Copyright © 2006 John Wiley & Sons, Ltd. [source] Three-dimensional finite element analyses of passive pile behaviourINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2006L. F. Miao Abstract Piles may be subjected to lateral soil pressures as a result of lateral soil movements from nearby construction-related activities such as embankment construction or excavation operations. Three-dimensional finite element analyses have been carried out to investigate the response of a single pile when subjected to lateral soil movements. The pile and the soil were modelled using 20-node quadrilateral brick elements with reduced integration. For compatibility between the soil,pile interface elements, 27-node quadrilateral brick elements with reduced integration were used to model the soil around the pile adjacent to the soil,pile interface. A Mohr,Coulomb elastic,plastic constitutive model with large-strain mode was assumed for the soil. The analyses indicate that the behaviour of the pile was significantly influenced by the pile flexibility, the magnitude of soil movement, the pile head boundary conditions, the shape of the soil movement profile and the thickness of the moving soil mass. Reasonable agreement is found between some existing published solutions and those developed herein. Copyright © 2005 John Wiley & Sons, Ltd. [source] Stresses due to vertical subsurface loading for an inhomogeneous cross-anisotropic half-spaceINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 12 2004Cheng-Der Wang Abstract In this article, we present the solutions for the stresses induced by four different loads associated with an axially loaded pile in a continuously inhomogeneous cross-anisotropic half-space. The planes of cross-anisotropy are parallel to the horizontal surface of the half-space, and the Young's and shear moduli are assumed to vary exponentially with depth. The four loading types are: an embedded point load for an end-bearing pile, uniform skin friction, linear variation of skin friction, and non-linear parabolic variation of skin friction for a friction pile. The solutions for the stresses due to the pile load are expressed in terms of the Hankel integral and are obtained from the point load solutions of the same inhomogeneous cross-anisotropic half-space which were derived recently by the authors (Int. J. Rock Mech. Min. Sci. 2003; 40(5):667,685). A numerical procedure is proposed to carry out the integral. For the special case of homogeneous isotropic and cross-anisotropic half-space, the stresses predicted by the numerical procedure agree well with the solutions of Geddes and Wang (Geotechnique 1966; 16(3):231,255; Soils Found. 2003; 43(5):41,52). An illustrative example is also given to investigate the effect of soil inhomogeneity, the type and degree of soil anisotropy, and the four different loading types on the vertical normal stress. The presented solutions are more realistic in simulating the actual stratum of loading problem in many areas of engineering practice. Copyright © 2004 John Wiley & Sons, Ltd. 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