• 제목/요약/키워드: Soil for foundation

검색결과 946건 처리시간 0.023초

Building frame - pile foundation - soil interaction analysis: a parametric study

  • Chore, H.S.;Ingle, R.K.;Sawant, V.A.
    • Interaction and multiscale mechanics
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    • 제3권1호
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    • pp.55-79
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    • 2010
  • The effect of soil-structure interaction on a single-storey, two-bay space frame resting on a pile group embedded in the cohesive soil (clay) with flexible cap is examined in this paper. For this purpose, a more rational approach is resorted to using the finite element analysis with realistic assumptions. Initially, a 3-D FEA is carried out independently for the frame on the premise of fixed column bases in which members of the superstructure are discretized using the 20-node isoparametric continuum elements. Later, a model is worked out separately for the pile foundation, by using the beam elements, plate elements and spring elements to model the pile, pile cap and soil, respectively. The stiffness obtained for the foundation is used in the interaction analysis of the frame to quantify the effect of soil-structure interaction on the response of the superstructure. In the parametric study using the substructure approach (uncoupled analysis), the effects of pile spacing, pile configuration, and pile diameter of the pile group on the response of superstructure are evaluated. The responses of the superstructure considered include the displacement at top of the frame and moments in the columns. The effect of soil-structure interaction is found to be quite significant for the type of foundation considered in the study. Fair agreement is observed between the results obtained herein using the simplified models for the pile foundation and those existing in the literature based on a complete three dimensional analysis of the building frame - pile foundation - soil system.

Evaluation of the influence of interface elements for structure - isolated footing - soil interaction analysis

  • Rajashekhar Swamy, H.M.;Krishnamoorthy, A.;Prabakhara, D.L.;Bhavikatti, S.S.
    • Interaction and multiscale mechanics
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    • 제4권1호
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    • pp.65-83
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    • 2011
  • In this study, two extreme cases of compatibility of the horizontal displacements between the foundation and soil are considered, for which the pressure and settlements of the isolated footings and member end actions in structural elements are obtained using the three dimensional models and numerical experiments. The first case considered is complete slip between foundation and soil, termed as the un-coupled analysis. In the second case of analysis, termed as the coupled analysis, complete welding is assumed of joints between the foundation and soil elements. The model and the corresponding computer program developed simulate these two extreme states of compatibility giving insight into the variation of horizontal displacements and horizontal stresses and their intricacies, for evaluation of the influence of using the interface elements in soil-structure interaction analysis of three dimensional multiscale structures supported by isolated footings.

Nonlinear analysis of finite beam resting on Winkler foundation with consideration of beam-soil interface resistance effect

  • Zhang, L.;Zhao, M.H.;Xiao, Y.;Ma, B.H.
    • Structural Engineering and Mechanics
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    • 제38권5호
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    • pp.573-592
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    • 2011
  • Comprehensive and accurate analysis of a finite foundation beam is a challenging engineering problem and an important subject in foundation design. One of the limitation of the traditional Winkler elastic foundation model is that the model neglects the effect of the interface resistance between the beam and the underneath foundation soil. By taking the beam-soil interface resistance into account, a deformation governing differential equation for a finite beam resting on the Winkler elastic foundation is developed. The coupling effect between vertical and horizontal displacements is also considered in the presented method. Using Galerkin method, semi-analytical solutions for vertical and horizontal displacements, axial force, shear force and bending moment of the beam under symmetric loads are presented. The influences of the interface resistance on the behavior of foundation beam are also investigated.

입력지반운동의 공간적 변화를 고려한 교량의 지진응답해석 (Seismic Response Analysis of Bridges Considering Spatial Variation of Input Ground Motion)

  • 최광규;강승우;국승규
    • 한국해양공학회지
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    • 제24권1호
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    • pp.76-82
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    • 2010
  • This paper presents a seismic response analysis of bridge structures considering the spatial variation of input ground motion. In earthquake analyses of structures, it is usually assumed that the input ground motion is the same at every support. However, this assumption is not justified for long structures like bridges, because observations have shown that the earthquake ground motion can vary considerably within relatively small distances. When the soil under the foundation is relatively soft and deep, an analysis of the foundation-soil interaction must always be performed. To consider the foundation-soil interaction, a soil response analysis is performed first, and after determining the material characteristics of the foundation element obtained by this foundation-soil interaction analysis, the seismic response analysis of a bridge superstructure with equivalent springs and dampers is performed. Finally, the influences of the spatial variation in the input motion, which are affected by different soil characteristics, are considered.

Analysis of the piled raft for three load patterns: A parametric study

  • Chore, H.S.;Siddiqui, M.J.
    • Coupled systems mechanics
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    • 제2권3호
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    • pp.289-302
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    • 2013
  • The piled raft is a geotechnical construction, consisting of the three elements-piles, raft and the soil, that is applied for the foundation of a tall buildings in an increasing number. The piled rafts nowadays are preferred as the foundation to reduce the overall and differential settlements; and also, provides an economical foundation option for circumstances where the performance of the raft alone does not satisfy the design requirements. The finite element analysis of the piled raft foundation is presented in this paper. The numerical procedure is programmed into finite element based software SAFE in order to conduct the parametric study wherein soil modulus and raft thickness is varied for constant pile diameter. The problems of piled raft for three different load patterns as considered in the available literature (Sawant et al. 2012) are analyzed here using SAFE. The results obtained for load pattern-I using SAFE are compared with those obtained by Sawant et al. (2012). The fair agreement is observed in the results which demonstrate the accuracy of the procedure employed in the present investigation. Further, substantial reduction in maximum deflections and moments are found in piled raft as compared to that in raft. The reduction in deflections is observed with increase in raft thickness and soil modulus. The decrease in maximum moments with increase in soil modulus is seen in raft whereas increase in maximum moments is seen in piled raft. The raft thickness and soil modulus affects the response of the type of the foundation considered in the present investigation.

Physico-chemical characteristics of mangrove soil in Gulf of Kachchh, Gujarat, India

  • Rajal, Patel;Lamb, Christian;Roshan, Bhagat;Kamboj, R.D.;Harshad, Salvi
    • Advances in environmental research
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    • 제8권1호
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    • pp.39-54
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    • 2019
  • This paper presents comprehensive scientific details about mangrove soil in Gulf of Kachchh, Gujarat. A total of ten sites were studied during November, 2011 to December, 2014 in order to know the physico-chemical characteristics of mangrove soil. The results indicated that the soil in GoK had silty loam texture. Other physico-chemical parameters ranged as; pH: 7.39-7.61, Bulk Density: 0.30 g/㎤-0.54 g/㎤, Particle Density: 1.26 g/㎤-1.76 g/㎤, Organic Carbon: 0.70%-1.13%, Organic Matter: 1.01%-1.74% and Moisture Content: 33.45%-56.38%. The paper would be useful to the stakeholders, coastal managers and scientific communities to know the mangrove soil conditions of Gulf of Kachchh for management and planning for conservation of mangrove ecosystem.

Numerical Analysis for High-rise Building Foundation and Further Investigations on Piled Raft Design

  • Won, Jinoh;Lee, Jin Hyung;Cho, Chunwhan
    • 국제초고층학회논문집
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    • 제4권4호
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    • pp.271-281
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    • 2015
  • This paper introduces detailed three-dimensional numerical analyses on a bored pile foundation for a high-rise building. A static load test was performed on a test pile and a numerical model of a single pile, which was calibrated by comparing it with the test result. The detailed numerical analysis was then conducted on the entire high-rise building foundation. Further study focused on soil pressures under the base slab of a piled raft foundation. Total seven cases with different pile numbers and raft-soil contact conditions were investigated. The design criteria of a foundation, especially settlement requirement were satisfied even for the cases with fewer piles under considerable soil pressure beneath the base slab. The bending moment for the structural design of the base slab was reduced by incorporating soil pressures beneath the base slab along with bored piles. Through the comparative studies, it was found that a more efficient design can be achieved by considering the soil pressure beneath the slab.

Distribution of elastoplastic modulus of subgrade reaction for analysis of raft foundations

  • Rahgooy, Kamran;Bahmanpour, Amin;Derakhshandi, Mehdi;Bagherzadeh-Khalkhali, Ahad
    • Geomechanics and Engineering
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    • 제28권1호
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    • pp.89-105
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    • 2022
  • The behavior of the soil subgrade is complex and irregular against loads. When modeling, the soil is often replaced by a more straightforward system called a subgrade model. The Winkler method of linear elastic springs is a popular method of soil modeling in which the spring constant shows the modulus of subgrade reaction. In this research, the factors affecting the distribution of the modulus of subgrade reaction of elastoplastic subgrades are examined. For this purpose, critical theories about the modulus of subgrade reaction were examined. A square raft foundation on a sandy soil subgrade with was analyzed at different internal friction angles and Young's modulus values using ABAQUS software. To accurately model the actual soil behavior, the elastic, perfectly plastic constitutive model was applied to investigate a foundation on discrete springs. In order to increase the accuracy of soil modeling, equations have been proposed for the distribution of the subgrade reaction modulus. The constitutive model of the springs is elastic, perfectly plastic. It was observed that the modulus of subgrade reaction under an elastic load decreased when moving from the corner to the center of the foundation. For the ultimate load, the modulus of subgrade reaction increased as it moved from the corner to the center of the foundation.

Soil interaction effects on sloshing response of the elevated tanks

  • Livaoglu, Ramazan
    • Geomechanics and Engineering
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    • 제5권4호
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    • pp.283-297
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    • 2013
  • The aim of this paper is to investigate how the soil-structure interaction affects sloshing response of the elevated tanks. For this purpose, the elevated tanks with two different types of supporting systems which are built on six different soil profiles are analyzed for both embedded and surface foundation cases. Thus, considering these six different profiles described in well-known earthquake codes as supporting medium, a series of transient analysis have been performed to assess the effect of both fluid sloshing and soil-structure interaction (SSI). Fluid-Elevated Tank-Soil/Foundation systems are modeled with the finite element (FE) technique. In these models fluid-structure interaction is taken into account by implementing Lagrangian fluid FE approximation into the general purpose structural analysis computer code ANSYS. A 3-D FE model with viscous boundary is used in the analyses of elevated tanks-soil/foundation interaction. Formed models are analyzed for embedment and no embedment cases. Finally results from analyses showed that the soil-structure interaction and the structural properties of supporting system for the elevated tanks affected the sloshing response of the fluid inside the vessel.

Seismic response of bridge pier supported on rocking shallow foundation

  • Deviprasad, B.S.;Dodagoudar, G.R.
    • Geomechanics and Engineering
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    • 제21권1호
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    • pp.73-84
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    • 2020
  • In the seismic design of bridges, formation of plastic hinges plays an important role in the dissipation of seismic energy. In the case of conventional fixed-base bridges, the plastic hinges are allowed to form in the superstructure alone. During seismic event, such bridges may be safe from collapse but the superstructure undergoes significant plastic deformations. As an alternative design approach, the plastic hinges are guided to form in the soil thereby utilizing the inevitable yielding of the soil. Rocking foundations work on this concept. The formation of plastic hinges in the soil reduces the load and displacement demands on the superstructure. This study aims at evaluating the seismic response of bridge pier supported on rocking shallow foundation. For this purpose, a BNWF model is implemented in OpenSees platform. The capability of the BNWF model to capture the SSI effects, nonlinear behavior and dynamic loading response are validated using the centrifuge and shake table test results. A comparative study is performed between the seismic response of the bridge pier supported on the rocking shallow foundation and conventional fixed-base foundation. Results of the study have established the beneficial effects of using the rocking shallow foundation for the seismic response analysis of the bridge piers.