scholarly journals Study on the bending moment diagram of straight and inclined pile groups in saturated sands with different thicknesses

2020 ◽  
Vol 8 (7) ◽  
pp. 235-238
Author(s):  
Yurun Li ◽  
Haotian Yang ◽  
Dongfeng Qiang ◽  
Yan Liang
Keyword(s):  
Bending Moment ◽  
Pile Groups ◽  
Saturated Sands ◽  
Inclined Pile

Seismic Response of Pile Groups Improved with Deep Cement mixing Columns in Liquefiable Sand: Shaking Table Tests

2021 ◽  
Author(s):  
Dingwen Zhang ◽  
Anhui Wang ◽  
Xuanming Ding
Keyword(s):  
Seismic Behavior ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Pile Group ◽  
Shaking Table ◽  
Excess Pore Pressure ◽  
Shaking Table Tests ◽  
Pile Groups ◽  
Acceleration Response ◽  
Table Model

A series of shaking table model tests were performed to examine the effects of deep cement mixing (DCM) columns with different reinforcement depths on the seismic behavior of a pile group in liquefiable sand. Due to the DCM column reinforcement, the fundamental natural frequency of the model ground increases noticeably. The excess pore pressure of soils reduces with the increase of reinforcement depths of the DCM columns. Before liquefaction, the acceleration response of soils in the improved cases is obviously lower than that in the unimproved case, but the acceleration attenuation is greater after liquefaction in the unimproved case. Moreover, the lateral displacement of the superstructure, the settlement of the raft, and the bending moment of the piles in the improved cases are significantly reduced compared to those in the unimproved case, and the reduction ratios rise with the increase of reinforcement depth of the DCM columns. However, reinforcement by the DCM columns may result in the variation of the location of the maximum moment that occurs in the pile.

scholarly journals Comparison of Induced Deflection and Forces in Piles Adjacent to Tunnelling and Deep Excavation in 2D and 3D Problems

2018 ◽  
Vol 203 ◽  
pp. 04011
Author(s):  
Ong Yin Hoe ◽  
Hisham Mohamad
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
3D Models ◽  
Deep Excavation ◽  
Pile Groups ◽  
Out Of Plane ◽  
National University ◽  
Plane Direction ◽  
2D And 3D ◽  
2D Model

There is a trend in Malaysia and Singapore, engineers tend to model the effect of TBM tunneling or deep excavation to the adjacent piles in 2D model. In the 2D model, the pile is modelled using embedded row pile element which is a 1-D element. The user is allowed to input the pile spacing in out-of-plane direction. This gives an impression to engineers the embedded pile row element is able to model the pile which virtually is a 3D problem. It is reported by Sluis (2014) that the application of embedded pile row element is limited to 8D of pile length. It is also reported that the 2D model overestimates the axial load in pile and the shear force and bending moment at pile top and it is not realistic in comparison to 3D model. In this paper, the centrifuge results of single pile and 6-pile group - tunneling problem carried out in NUS (National University of Singapore) are back-analysed with Midas GTS 3D and a 2D program. In a separate case study, pile groups adjacent to a deep excavation is modelled by 3D and 2D program. This paper compares the deflection and forces in piles in 2D and 3D models.

scholarly journals Numerical Study of Laterally Loaded Piles in Soft Clay Overlying Dense Sand

2021 ◽  
Vol 7 (4) ◽  
pp. 730-746
Author(s):  
Amanpreet Kaur ◽  
Harvinder Singh ◽  
J. N. Jha
Keyword(s):  
Layer Thickness ◽  
Soft Clay ◽  
Bending Moment ◽  
Layered Soil ◽  
Clay Layer ◽  
Pile Groups ◽  
Dense Sand ◽  
Lateral Capacity ◽  
Laterally Loaded ◽  
Pile Length

This paper presents the results of three dimensional finite element analysis of laterally loaded pile groups of configuration 1×1, 2×1 and 3×1, embedded in two-layered soil consisting of soft clay at liquid limit overlying dense sand using Plaxis 3D. Effects of variation in pile length (L) and clay layer thickness (h) on lateral capacity and bending moment profile of pile foundations were evaluated by employing different values of pile length to diameter ratio (L/D) and ratio of clay layer thickness to pile length (h/L) in the analysis. Obtained results indicated that the lateral capacity reduces non-linearly with increase in clay layer thickness. Larger decrease was observed in group piles. A non-dimensional parameter Fx ratio was defined to compare lateral capacity in layered soil to that in dense sand, for which a generalized expression was derived in terms of h/L ratio and number of piles in a group. Group effect on lateral resistance and maximum bending moment was observed to become insignificant for clay layer thickness exceeding 40% of pile length. For a fixed value of clay layer thickness, lateral capacity and bending moment in a single pile increased significantly with increase in pile length only up to an optimum embedment depth in sand layer which was found to be equal to three times pile diameter and 0.21 times pile length for pile with L/D 15. Scale effect on lateral capacity has also been studied and discussed. Doi: 10.28991/cej-2021-03091686 Full Text: PDF

Soil-structure interaction effects in single bridge piers founded on inclined pile groups

2017 ◽  
Vol 92 ◽  
pp. 52-67 ◽  
Author(s):  
Sandro Carbonari ◽  
Michele Morici ◽  
Francesca Dezi ◽  
Fabrizio Gara ◽  
Graziano Leoni
Keyword(s):  
Soil Structure ◽  
Interaction Effects ◽  
Bridge Piers ◽  
Soil Structure Interaction ◽  
Pile Groups ◽  
Structure Interaction ◽  
Inclined Pile

Expanded superposition method for impedance functions of inclined-pile groups

2015 ◽  
Vol 40 (2) ◽  
pp. 185-206 ◽  
Author(s):  
M. Saitoh ◽  
L. A. Padrón ◽  
J. J. Aznárez ◽  
O. Maeso ◽  
C. S. Goit
Keyword(s):  
Superposition Method ◽  
Pile Groups ◽  
Inclined Pile ◽  
Impedance Functions

A numerical model for the dynamic analysis of inclined pile groups

2015 ◽  
Vol 45 (1) ◽  
pp. 45-68 ◽  
Author(s):  
Francesca Dezi ◽  
Sandro Carbonari ◽  
Michele Morici
Keyword(s):  
Numerical Model ◽  
Dynamic Analysis ◽  
Pile Groups ◽  
Inclined Pile

scholarly journals Numerical analysis of reducing tunneling effect on viaduct piles foundation by jet grouted wall

2021 ◽  
Vol 15 (1) ◽  
pp. 75-86
Author(s):  
Kamel Asker ◽  
Mohmed Tarek Fouad ◽  
Mohamed Bahr ◽  
Ahmed El-Attar
Keyword(s):  
Numerical Model ◽  
Interaction Mechanism ◽  
Back Analysis ◽  
Bending Moment ◽  
Pile Group ◽  
Tunneling Effect ◽  
Shield Tunnel ◽  
Pile Groups ◽  
Perfectly Plastic ◽  
Jet Grouting

Purpose. The target of this study is divided into two parts. The first part is concerned with capability of numerical model to simulate the tunneling process. The second part is related to studying the interaction mechanism between the tunnel, protection technique, and soil. This study themes are investigated by analyzing different protection technique configuration, considering different stiffness of the grouted wall, and applying different interface coefficient between the wall and the soil. Methods. The method used in this study to check the accuracy of the proposed numerical model is 4-D ABAQUS program. The typical excavation of a tunnel is simulated step by step with an assumed rate of tunnel advancement (0.5 to 1.5 m/hr). The soil material utilized in this model is elastic perfectly plastic (the Mohr-Сoulomb criterion), while elastic material is modeled as solid element (S4R) adopted for lining, grouting, filling gaps, shielding, constructing piles, and jet grouted wall. Findings. Results showed that the closer jet grouting to the tunnel with embedded length of 1.5 times tunnel diameter, the better effect on reducing the lateral deformation and bending moment generated on piles. Otherwise, increasing wall thickness more than double grouted column diameter would not affect its shielding efficiency. Furthermore, either increasing or decreasing friction coefficient even if rough between the grouted wall and soil had no effect on the pile behavior. Additionally, applying Mohr-Coulomb criteria for grouted wall with high stiffness allowed realistic response of the pile group. Originality.Capability of the proposed model is verified by back analysis of Changsha Subway Line 1 project, where the shield tunnel would be constructed near existing pile groups of L off-ramp of the Xinzhong Road viaduct. Practical implications. Increasing grouted wall configuration is more effective than mechanical properties or its interface coefficient with surrounded soil in mitigating tunneling effect on nearby piles. Keywords: tunneling, jet grouting, gield measurements, ABAQUS, Changsha Subway Line 1

scholarly journals Seismic Behaviour of Piles in Non-Liquefiable and Liquefiable Soil

2021 ◽  
Author(s):  
Fouad Hussein ◽  
Hesham El Naggar
Keyword(s):  
Finite Element ◽  
Ground Motion ◽  
Numerical Models ◽  
Bending Moment ◽  
Soil Liquefaction ◽  
Shaking Table ◽  
Pile Groups ◽  
Kinematic Interaction ◽  
Inertial Interaction ◽  
Liquefiable Soil

Abstract This paper investigates the nonlinear soil-pile-structure interaction (SPSI) employing three-dimensional (3D) nonlinear finite element models (FEM) verified with the results of large-scale shaking table tests of model pile groups-superstructure systems. The responses of piles in both liquefiable and non-liquefiable soil sites to ground motion with varying intensities were evaluated considering both kinematic and inertial interaction. The calculated piles and soil responses agreed well with the responses measured during the shaking events. The numerical models correctly predicted the different pile deformation modes that were exhibited in the experiments. The finite element analysis (FEA) was then employed to perform a parametric study to evaluate the kinematic and inertial effects on the piles' response, considering different ground motion levels and piles characteristics. It was found that the bending moment of piles in the liquefiable site increases significantly, compared to the non-liquefiable site, due to the loss of lateral support of the liquified soil, and the maximum bending moment occurs at the interface between the liquified and liquefied sand layers. The inertial interaction contributes the most to the bending moments at the pile top and the interface between the top clay and liquefied loose sand layers. For piles with a larger diameter, the bending moment due to kinematic interaction increases significantly, and the bending moment distribution corresponds to short (rigid) pile behaviour. In addition, the piles at the saturated site displace laterally as a rigid body during strong ground motions because the pile base loses the lateral support due to the soil liquefaction. Finally, the kinematic interaction effect becomes more significant for piles with higher elastic modulus.

scholarly journals Interaction between inclined pile groups subjected to harmonic vibrations

2013 ◽  
Vol 53 (6) ◽  
pp. 789-803 ◽  
Author(s):  
Mahmoud Ghazavi ◽  
Pedram Ravanshenas ◽  
M. Hesham El Naggar
Keyword(s):  
Pile Groups ◽  
Harmonic Vibrations ◽  
Inclined Pile
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