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1 – 10 of over 3000The dynamic response of the nuclear power plants (NPPs) with pile foundation reinforcement have not yet been systemically investigated in detail. Thus, there is an urgent need to…
Abstract
Purpose
The dynamic response of the nuclear power plants (NPPs) with pile foundation reinforcement have not yet been systemically investigated in detail. Thus, there is an urgent need to improve evaluation methods for nonlithological foundation reinforcements, as this issue is bound to become an unavoidable task.
Design/methodology/approach
A nonlinear seismic wave input method is adopted to consider both a nonlinear viscoelastic artificial boundary and the nonlinear properties of the overburden layer soil. Subsequently, the effects of certain vital parameters on the structural response are analyzed.
Findings
A suitable range for the size of the overburden foundation is suggested. Then, when piles are used to reinforce the overburden foundation, the peak frequencies in the floor response spectra (FRS) in the horizontal direction becomes higher (38%). Finally, the Poisson ratio of the foundation soil has a significant influence on the FRS peak frequency in the vertical direction (reduce 35%–48%).
Originality/value
The quantifiable results are performed to demonstrate the seismic responses with respect to key design parameters, including foundational dimensions, the Poisson Ratio of the soil and the depth of the foundation. The results can help guide the development of seismic safety requirements for NPPs.
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Mohamed Nabil Houhou, Tamir Amari and Abderahim Belounar
This paper aims to investigate the responses of single piles and pile groups due to tunneling-induced ground movements in a two-layered soil system. The analyses mainly focus on…
Abstract
Purpose
This paper aims to investigate the responses of single piles and pile groups due to tunneling-induced ground movements in a two-layered soil system. The analyses mainly focus on the additional single pile responses in terms of bending moment, lateral deflection, axial force, shaft resistance and pile settlement. Subsequently, a series of parametric studies were carried out to better understand the responses of single piles induced by tunneling. To give further understanding regarding the pile groups, a 2 × 2 pile group with two different pile head conditions, namely, free and capped, was considered.
Design/methodology/approach
Using the PLAXIS three-dimensional (3D) software, a full 3D numerical modeling is performed to investigate the effects of ground movements caused by tunneling on adjacent pile foundations. The numerical model was validated using centrifuge test data found in the literature. The relevance of the 3D model is also judged by comparison with the 2D plane strain model using the PLAXIS 2D code.
Findings
The numerical test results reveal that tunneling induces significant displacements and internal forces in nearby piles. The magnitude and distribution of internal forces depend mainly on the position of the pile toe relative to the tunnel depth and the distance between the pile and the vertical axis of the tunnel. As the volume loss increases from 1% to 3%, the apparent loss of pile capacity increases from 11% to 20%. By increasing the pile length from 0.5 to 1.5 times, the tunnel depth, the maximum pile settlement and lateral deflection decrease by about 63% and 18%, respectively. On the other hand, the maximum bending moment and axial load increase by about 7 and 13 times, respectively. When the pile is located at a distance of 2.5 times the tunnel diameter (Dt), the additional pile responses become insignificant. It was found that an increase in tunnel depth from 1.5Dt to 2.5Dt (with a pile length of 3Dt) increases the maximum lateral deflection by about 420%. Regarding the interaction between tunneling and group of piles, a positive group effect was observed with a significant reduction of the internal forces in rear piles. The maximum bending moment of the front piles was found to be higher than that of the rear piles by about 47%.
Originality/value
Soil is a complex material that shows differently in primary loading, unloading and reloading with stress-dependent stiffness. This general behavior was not possibly being accounted for in simple elastic perfectly plastic Mohr–Coulomb model which is often used to predict the behavior of soils. Thus, in the present study, the more advanced hardening soil model with small-strain stiffness (HSsmall) is used to model the non-linear stress–strain soil behavior. Moreover, unlike previous studies THAT are usually based on the assumption that the soil is homogeneous and using numerical methods by decoupled loadings under plane strain conditions; in this study, the pile responses have been exhaustively investigated in a two-layered soil system using a fully coupled 3D numerical analysis that takes into account the real interactions between tunneling and pile foundations. The paper presents a distinctive set of findings and insights that provide valuable guidance for the design and construction of shield tunnels passing through pile foundations.
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Tamir Amari and Mohamed Nabil Houhou
This paper aims to investigate single pile and pile group responses due to deep braced excavation-induced soil movement in soft clay overlying dense sand. The analysis focuses…
Abstract
Purpose
This paper aims to investigate single pile and pile group responses due to deep braced excavation-induced soil movement in soft clay overlying dense sand. The analysis focuses first on the response of vertical single pile in terms of induced bending moment, lateral deflection, induced axial force, skin resistance distribution and pile settlement. To better understand the single pile behaviour, a parametric study was carried out. To provide further insights about the response of pile group system, different pile group configurations were considered.
Design/methodology/approach
Using the explicit finite element code PLAXIS 3 D, a full three-dimensional numerical analysis is carried out to investigate pile responses when performing an adjacent deep braced excavation. The numerical model was validated based on the results of a centrifuge test. The relevance of the 3 D model is also judged by comparison with the 2 D plane strain model using the PLAXIS 2 D code.
Findings
The results obtained allowed a thorough understanding of the pile response and the soil–pile–structure interactions phenomenon. The findings reveal that the deep excavation may cause appreciable bending moments, lateral deflections and axial forces in nearby piles. The parametric study showed that the pile responses are strongly influenced by the excavation depth, relative pile location, sand density, excavation support system and pile length. It also showed that the response of a pile within a group depends on its location in relation to the other piles of the pile group, its distance from the retaining wall and the number of piles in the group.
Originality/value
Unlike previous studies which investigated the problem in homogeneous geological context (sand or clay), in this paper, the pile response was thoroughly studied in a multi-layered soil using 3 D numerical simulation. To take into account the small-strain nonlinear behaviour of the soil, the Hardening soil model with small-strain stiffness was used in this analysis. For a preliminary design, this numerical study can serve as a practical basis for similar projects.
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Yogendra Tandel and Gaurang Vesmawala
Piles often carry combination of axial and lateral. Currently, piles are designed separately for axial and lateral load. In the literature, few information is available on the…
Abstract
Purpose
Piles often carry combination of axial and lateral. Currently, piles are designed separately for axial and lateral load. In the literature, few information is available on the influence of axial load on lateral behaviour of the pile. This paper aims to present the results of load deformation of a pile under pure lateral load and combined axial and lateral load.
Design/methodology/approach
The field load tests were carried out on four different pile diameters at two different bridge sites. Moreover, the paper addresses the numerical simulation of filed load test carried out on the pile under the combination of axial and horizontal load.
Findings
After field load tests and numerical simulation, it was found that the vertical load had a remarkable effect on the lateral load response of a pile. The lateral deflection of the pile was decreased about 25% under the effect of vertical load. In addition to this, the results from field and numerical simulation are quite comparable.
Originality/value
Typical field load tests were simulated numerically. This research adds a value in the areas of pile foundation subjected to vertical and lateral load particularly for structure such as transmission line tower and jetty.
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Abdelkrim Ferchat, Mohamed Nabil Houhou and Sadok Benmebarek
This paper aims to investigate the pile group efficiency based on the load-settlement response in soft clay conditions, considering several pile configurations using a variable…
Abstract
Purpose
This paper aims to investigate the pile group efficiency based on the load-settlement response in soft clay conditions, considering several pile configurations using a variable number of piles and pile spacing. The overall objective of the present paper is to provide further insight into the mechanical response of the pile group and aim at helping the engineers in taking a logical path in an iterative design process for pile group efficiency.
Design/methodology/approach
To investigate the pile group efficiency, three-dimensional (3D) numerical simulations were performed using the finite-difference code FLAC3D.
Findings
The obtained numerical results are validated by comparing them to those of similar subgrade structure and in comparable geological conditions provided within the literature. The results indicated that although the bearing capacity of the pile group increases with increasing number of piles, the efficiency of the pile group is very important for a small number of piles. However, increasing of pile spacing has a positive effect on pile group efficiency depending on piles number and settlement level. The pertinence of the 3D numerical results of efficiency coefficient is judged by comparison with those obtained from the most popular formulas available in the literature.
Originality/value
A predicted model is also proposed which is validated with the obtained numerical results to a better goodness of fit.
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Analysis of designing and controlling the failure of marine structures attached to the bottom of the sea under dynamic load obtained from the sea waves is one of the main…
Abstract
Purpose
Analysis of designing and controlling the failure of marine structures attached to the bottom of the sea under dynamic load obtained from the sea waves is one of the main engineering challenges in recent years. The circumstances of the onshore marine structures have their own complexity and the difficulty due to the effect of hydrodynamic factors and dynamic responses which are dominant in the marine environment. The paper aims to discuss these issues.
Design/methodology/approach
The structure elements are composed of the metal pipe with a length of 5 m, outside diameter of 20 cm and thickness of 1.5 mm. the failure control with a safety factor of 2 indicates the absence of the above marine structure failure. It has been diagnosed to be trustworthy and reliable.
Findings
In this study, the control of marine steel structure failure with the height of 60 m under the dynamic load of the sea water waves having sinusoidal shape in the Caspian Sea has been studied and analyzed.
Originality/value
In this paper, the minimum and maximum internal force and movement in six directions of freedom were obtained for each element. To analyze and control the failure, the combination of stresses caused by static and dynamic loads has been used. According to the regulation of 10-360-AISC, the control was conducted.
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Jonathan A. Rhoades and Josh A. Arnold
The purpose of the present studies was to derive an integrative taxonomy of responses to social conflict. In Study 1, we had college‐age participants sort 33 responses to…
Abstract
The purpose of the present studies was to derive an integrative taxonomy of responses to social conflict. In Study 1, we had college‐age participants sort 33 responses to conflict, taken from various research domains, according to their similarities. From this, we generated two different classification systems: a very simple low‐dimensional system, obtained through multi‐dimensional scaling; and a complex high‐dimensional system, obtained through cluster analysis. To aid in the interpretation of the structures, in Study 2 we collected a set of ratings on each of the conflict responses. The results from Study 2 indicated that many of the labels used to describe conflict responses in past research could be used to describe some aspects of these taxonomies. However, no dimension or set of dimensions was sufficient to describe all classes of conflict responses. The results are discussed in terms of their larger theoretical and practical implications.
Zhi Ding, Xinjiang Wei, Xiao Zhang and Xinsheng Yin
The shield tunnels closely constructed near the foundations have an inevitable influence on the structures, even results in the large settlement or uplift of the structures.
Abstract
Purpose
The shield tunnels closely constructed near the foundations have an inevitable influence on the structures, even results in the large settlement or uplift of the structures.
Design/methodology/approach
The comparison of structural deformation of three different foundations is presented based on the field monitoring data.
Findings
Shield tunnelling parameters vary for the different types of foundations. For the long pile foundations, the recommended speed is 3 to 4 cm/min, the grouting pressure is about 0.3 MPa and the grouting rate ranges from 150 to 180.
Originality/value
The study based on the field monitoring data is rarely reported, especially the topic about the structural deformation of different types of the foundations.
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Maher Taha El-Nimr, Ali Mohamed Basha, Mohamed Mohamed Abo-Raya and Mohamed Hamed Zakaria
To predict the real behavior of the full-scale model using a scale model, optimized simulation should be achieved. In reinforced concrete (RC) models, scaling can be substantially…
Abstract
Purpose
To predict the real behavior of the full-scale model using a scale model, optimized simulation should be achieved. In reinforced concrete (RC) models, scaling can be substantially more critical than in single-material models because of multiple reasons such as insufficient bonding strength between small-diameter steel bars and concrete, and excessive aggregate size. Overall, there is a shortfall of laboratory and field-testing studies on the behavior of secant pile walls under lateral and axial loads. Accordingly, the purpose of this study is to investigate the validity and the performance of the 1/10th scaled RC secant pile wall under the influence of different types of loading.
Design/methodology/approach
The structural performance of the examined models was evaluated using two types of tests: bending and axial compression. A self-compacting concrete mix was suggested, which provided the best concrete mix workability and appropriate compressive strength.
Findings
Under axial and bending loads, the failure modes were typical. Where the plain and reinforced concrete piles worked in tandem to support the load throughout the loading process, even when they failed. The experimental results were relatively consistent with some empirical equations for calculating the modulus of elasticity and critical buckling load. This confirmed the validity of the proposed model.
Originality/value
According to the analysis and verification of experimental tests, the proposed 1/10th scaled RC secant pile model can be used for future laboratory purposes, especially in the field of geotechnical engineering.
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Abhishek Sharma and Ravi Kumar Sharma
The purpose of this paper is to provide a cost-effective foundation technique for the design of foundations of transmission towers, heavily loaded structures, etc.
Abstract
Purpose
The purpose of this paper is to provide a cost-effective foundation technique for the design of foundations of transmission towers, heavily loaded structures, etc.
Design/methodology/approach
Experimental model tests are conducted in a model test tank to find out the effect of length and diameter of geogrid encased granular pile anchors, the relative density of sand and the angle of inclination of the pile from the vertical on uplift behavior of granular pile anchors.
Findings
The uplift capacity of the geogrid encased granular pile anchor increased with increasing length and diameter of granular pile anchor. Further, increasing the relative density of surrounding soil increased uplift capacity of geogrid encased granular pile anchor system. Moreover, increasing the angle of inclination of loading also increased uplift capacity of whole system. Thus, the proposed system can be effectively used in field for further applications.
Originality/value
The paper is helpful for the engineers looking for cost-effective foundation techniques for heavily loaded structures.
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