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Foundation analysis and design

01 Jan 1968-
TL;DR: In this paper, Fondation de soutenagement et al. presented a reference record for Dimensionnement Reference Record created on 2004-09-07, modified on 2016-08-08.
Abstract: Keywords: Fondation ; Mur de soutenement ; Pieux ; Capacite portante ; Ancrage ; Dimensionnement Reference Record created on 2004-09-07, modified on 2016-08-08
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Dissertation
01 Jan 2015
TL;DR: In this article, the authors evaluate the performance of a carretera in terms of the capacity of the capas of the pavimento and the degree of the humedad of the carreteras.
Abstract: La conservacion del patrimonio vial no debe ser una opcion sino mas bien una obligacion de las administraciones publicas que deben preservar las inversiones como un valor cuya amortizacion acelerada puede producir un impacto grave en la economia. La inversion en conservacion suele estar por debajo de las cifras recomendadas por el Banco Mundial (2 % del valor patrimonial) y, en este sentido, cualquier avance tecnico que permita optimizar las inversiones de manera preventiva puede constituir una ventaja en los costes de mantenimiento. Uno de los factores clave a la hora de dimensionar una rehabilitacion de tipo estructural es conocer la capacidad portante de las capas del pavimento. Las capas de rodadura que estan formadas por mezclas bituminosas o bien por hormigones hidraulicos y las capas inferiores hasta llegar a la explanada suelen estar formadas por materiales granulares cuyas caracteristicas mecanicas se ven influenciadas, en gran medida, por la humedad que poseen. En algunos metodos y normativas de rehabilitacion estructural se aplican factores de correccion sobre la medida de la deformacion que se produce bajo la aplicacion de una determinada carga y que responde a la totalidad de la estructura del pavimento sin discernir que parte de la misma corresponde a cada capa. La presente tesis pretende establecer una relacion entre las precipitaciones y los valores de humedad de las capas granulares asi como el valor de los modulos de elasticidad de dichas capas en funcion de la humedad. El conocimiento de estos valores y su variabilidad permitira dimensionar cualquier rehabilitacion estructural de un modo mas homogeneo y racional. De manera secuencial, a lo largo del desarrollo de la presente tesis, se han generado en laboratorio una serie de suelos que responden a una tipologia utilizada en los firmes de carreteras, posteriormente se ha evaluado en laboratorio su capacidad portante en funcion del grado de humedad de dichas capas. De manera paralela se han estudiado diferentes modelos conocidos para prever la infiltracion del agua de lluvia, definiendo el mas adecuado que, por capas, permite conocer el grado de humedad de los materiales granulares a diferentes profundidades en funcion de las precipitaciones y del tiempo. Finalmente se ha tratado de contrastar las hipotesis que se extraen de laboratorio y de los modelos de calculo instalando en un tramo de carretera una serie de sensores de humedad a diferentes profundidades, colocando unas estaciones meteorologicas que han registrado las lluvias entre otros parametros y, al mismo tiempo, se han tomado medidas de deflexiones durante un ano en la zona de ensayo. El analisis de los resultados obtenidos ha permitido avanzar en el conocimiento del comportamiento mecanico de los pavimentos con el objetivo de precisar los calculos a la hora de dimensionar una rehabilitacion y, por lo tanto, optimizar las inversiones en el mantenimiento de los mismos. ----------ABSTRACT---------- The conservation of road assets should not be an option but a requirement for governments, that must preserve investments as a value which accelerated depreciation may cause serious impact on the economy. Investment in conservation is often below the recommendations given by the World Bank (2% in value). In this sense, any technical advance to optimize investments proactively can be an advantage in maintenance costs . One of the key factors when designing structural rehabilitation is the determination of the bearing capacity of the pavement layers. Road layers are formed by bituminous mixtures or hydraulic concrete as well as a set of lower layers usually made of unbound granular materials whose mechanical characteristics are largely influenced by the contained moisture. In some methods and regulations for structural rehabilitation, correction factors are applied to the measurement of the deformation occurring under application of a given load. Such deformations reflect all of the pavement structure without discerning which portion corresponds to each layer. This doctoral thesis aims to establish a relationship between rainfall and humidity values of the granular layers and the value of the modulus of elasticity of such layers depending on the humidity. The knowledge of these values and their variability allow dimensioning any structural rehabilitation in a more homogeneous and rational way. Sequentially throughout the development of this thesis, several series of soils that respond to a typology used in road pavements, were generated in the laboratory, subsequently evaluated their bearing capacity depending on the humidity contained in the layers. In parallel, we have studied different reported models to predict the infiltration of rainwater, determining the most appropriate for granular layers, which has allowed to know the moisture content of granular materials at different depths depending on rainfall and time. Finally, we have tried to test the hypotheses that are extracted from laboratory and computational models by installing some series of humidity sensors at different depths on a stretch of road, along with placing weather stations that have recorded rainfall among other parameters. At the same time, deflection measurements have been taken for a year in the test area. The analysis of the results has provided useful knowledge on the mechanical behavior of pavements in order to clarify the calculations when designing rehabilitation and, therefore, optimizing investments for road assets maintaining.

2 citations


Cites background from "Foundation analysis and design"

  • ...Inicialmente, se intentó acometer el problema de obtención de las tensiones basándose en las teoŕıas de Boussinesq para un macizo homogéneo elástico seminfinito e isótropo sometido a una carga vertical uniformemente repartida según un área circular [4] [6], obteniéndose resultados muy conservadores para pavimentos, ya que sobrevaloraba el estado de tensiones en el interior del macizo, con lo que se obtienen espesores mayores de los necesarios....

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Journal ArticleDOI
TL;DR: In this article, a simplified design approach for estimation of wall deflection where diaphragm wall is assumed as continuous beam is presented, where Earth pressure in the backfill side is taken as load, exerted on the beam and strut load along with earth pressure in cut side represents support of the beam.
Abstract: The construction of braced excavations in urban areas requires control of surrounding ground movements since excessive ground movements damage adjacent properties. Reasonably good amount of work on numerical analysis and field studies on the estimation of ground surface settlement adjacent to excavation have been reported in the literature. However, theoretical studies or mathematical modeling have not been well addressed in the literature. This paper presents a simplified design approach for estimation of wall deflection where diaphragm wall is assumed as continuous beam. Earth pressure in the backfill side is taken as load, exerted on the beam and strut load along with earth pressure in cut side represents support of the beam. Peck’s earth pressure diagram for braced wall is used for load calculation while Terzaghi’s equation is considered to derive coefficient of modulus of subgrade reaction. Applicability of the proposed approach has been verified by comparing the estimated values of wall deflection with the measured values of three different case studies.

2 citations

Journal ArticleDOI
TL;DR: A steel cofferdam is built by assembling many pieces of flat or circular web sheet piles to interlock with each other as discussed by the authors, which causes an increase in the construction costs and time as compared to an onshore foundation of a bridge pier.
Abstract: It is complicated and difficult to construct the offshore foundation of a bridge pier because of the cofferdam installation, which causes an increase in the construction costs and time as compared to an onshore foundation of a pier. A conventional steel cofferdam has common configurations such as circular, diaphragm, and cloverleaf to exclude water during excavation and ensure construction in dry conditions [1]. A steel cofferdam is built by assembling many pieces of flat or circular web sheet piles to interlock with each other. Frequent pauses and accidents during this process are expected due to

2 citations

Journal ArticleDOI
TL;DR: Technology applied for the global optimization of grillage-type pile foundations (further grillages) is presented and the article describes technology enabling the integration of MatLab and Fortran environments.
Abstract: The purpose of the paper is to present technology applied for the global optimization of grillage-type pile foundations (further grillages). The goal of optimization is to obtain the optimal layout of pile placement in the grillages. The problem can be categorized as a topology optimization problem. The objective function is comprised of maximum reactive force emerging in a pile. The reactive force is minimized during the procedure of optimization during which variables enclose the positions of piles beneath connecting beams. Reactive forces in all piles are computed utilizing an original algorithm implemented in the Fortran programming language. The algorithm is integrated into the MatLab environment where the optimization procedure is executed utilizing a genetic algorithm. The article also describes technology enabling the integration of MatLab and Fortran environments. The authors seek to evaluate the quality of a solution to the problem analyzing experimental results obtained applying the proposed technology.

2 citations

Journal ArticleDOI
TL;DR: In this article, the effect of relative density of sandy soils on the damper problems is examined. But the ground effects are not taken into account, and the added dampers placed according to the different objectives have improved the structural response and also reduced the harmful effects caused by poor ground conditions.
Abstract: Superstructure models used in optimal damper problem are usually connected rigidly to ground, and ground effects are not taken into account. This study reveals the effect of relative density of sandy soils on the damper problems. The optimal distribution of viscous dampers and the effect of relative density of sandy soils on the dynamic response of structure for an n-storey shear-building model are examined. The governing equation of soil–structure model is established and the equations in the frequency domain are derived using Fourier transformation. Steepest direction search algorithm is used as an optimization method. The four different objective functions, which are the top displacement, top absolute acceleration, base shear and base moment behaviour of the structure defined in the frequency domain, are minimized. The fundamental mode response of structural model is taken into account, and the time history analyses are conducted by using El Centro (NS) earthquake acceleration record. The effect of relative density of sandy soils on the responses of structure with optimal design and the effect of the variation of total damper capacity used in the optimization stage are investigated. It is observed that the variation of the objective functions, total damping capacity and ground conditions can change the optimal design. The low displacement in damped systems has occurred in comparison with no damper. The structural response in the rigid case is less than those in the different relative density of sandy soils. The added dampers placed according to the different objectives have improved the structural response and also reduced the harmful effects caused by poor ground conditions.

2 citations