scholarly journals Parametric Study of Pile Response to Side-by-Side Twin Tunneling in Stiff Clay

2020 ◽  
Vol 10 (2) ◽  
pp. 5361-5366
Author(s):  
N. Mangi ◽  
D. K. Bangwar ◽  
H. Karira ◽  
S. Kalhoro ◽  
G. R. Siddiqui
Keyword(s):  
Parametric Study ◽  
Three Dimensional ◽  
Bending Moment ◽  
Small Strain ◽  
Percentage Difference ◽  
Stiff Clay ◽  
The One ◽  
Numerical Parametric Study ◽  
Pile Response ◽  
Twin Tunnels

A three dimensional coupled-consolidation numerical parametric study was carried out in order to gain new insight of single pile response to side-by-side twin tunneling in saturated stiff clay. An advanced hypo plasticity (clay) constitutive model with small-strain stiffness was adopted. The effects of relative to the pile tunnel depths were investigated by simulating the twin tunnels near the pile at various depths of tunnels, namely near the pile shaft, adjacent to the pile toe, and below the pile toe. It was found that the second tunneling in each case resulted in a larger settlement than the one due to the first tunneling with a maximum percentage difference of 175% in the case of twin tunneling near the mid-depth of the shaft. This occurred due to the degradation of clay stiffness around the pile during the first tunneling. Conversely, the first tunneling-induced bending moment was reduced substantially during the second tunneling. The most critical location of twin tunnels relative to the pile was found to be below the pile toe.

scholarly journals The Effects of Multipropped Deep Excavation-Induced Ground Movements on Adjacent High-Rise Building Founded on Piled Raft in Sand

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Mukhtiar Ali Soomro ◽  
Naeem Mangi ◽  
Wen-Chieh Cheng ◽  
Dildar Ali Mangnejo
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
Small Strain ◽  
High Rise ◽  
Piled Raft ◽  
Interstorey Drift ◽  
Numerical Parametric Study ◽  
Soil Behaviour ◽  
Pile Length ◽  
Storey Building

In this paper, a three-dimensional numerical parametric study was conducted to predict the deformation mechanism of a 20-storey building sitting on a (4 × 4) piled raft to an adjacent 25 m deep basement excavation. The influences of different excavation depths were investigated. An advanced hypoplastic sand model (which is capable of taking small-strain stiffness into account) was adopted to capture soil behaviour. The computed results revealed that excavation adjacent to a building resting on the piled raft caused significant settlement, differential settlement, lateral deflection, and interstorey drift in the building. With settlement due to working load (i.e., 4.8dp%), the total settlements of the building (7.8dp%) exceed the maximum allowable foundation settlement (i.e., 50 mm). In addition, substantial bending moment, shear forces, and changes in axial load distribution along pile length were induced. The findings from this study revealed that the building and pile responses are significantly influenced by the excavation depth.

Three-Dimensional Numerical Analyses of Pile Response due to Braceded Excavation-Induced Lateral Soil Movement

2014 ◽  
Vol 580-583 ◽  
pp. 524-531 ◽  
Author(s):  
Lin Li ◽  
Xiao Xin Hu ◽  
Guang Hui Dong ◽  
Ju Liu
Keyword(s):  
Lateral Displacement ◽  
Three Dimensional ◽  
Bending Moment ◽  
Elastic Behavior ◽  
Pile Head ◽  
Soil Pressure ◽  
Soil Movement ◽  
Standard Problem ◽  
Modified Cam Clay ◽  
Pile Response

Using the explicit finite difference code FLAC3D, the behavior of pile adjacent to braced excavation is investigated. The Modified-cam clay constitutive model was employed to model the non-linear stress-strain soil behavior, and the pile was assumed to have linear elastic behavior. The interface model incorporated in FLAC3D code was used to simulate the soil/pile contact, The built-in 'fish' language was used to calculate the data demanded. The pile response such as pile deflection, bending moment and lateral soil pressure were studied, and it is shown that the pile response is different from that caused by the excavations which are unstructted. In "standard" problem, the effect of different pile head constraints on the pile response was investigated, the effect of lateral displacement of the wall, distance from the excavation face, pile stiffness, pile length and axial load on the pile response are also investigated when the pile head is constrained from deflection. The research finding was compared with other published case history and reasonably good agreement was found between them.

Analysis of the Dynamic Behaviour of Flexible Risers Considering Hysteretic Damping

2003 ◽  
Author(s):  
Marcos Q. de Siqueira ◽  
Jose´ Renato M. de Sousa ◽  
Ma´rcio M. Mourelle
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Dynamic Behaviour ◽  
Traditional Approach ◽  
Three Dimensional ◽  
Bending Moment ◽  
Finite Element Implementation ◽  
Hysteretic Damping ◽  
Flexible Risers ◽  
The One

This paper proposes a three-dimensional beam element that can predict the dynamic response of flexible risers considering their bending hysteretic behaviour. The finite element implementation relies on a previously presented co-rotated beam finite element and an analytical formulation for determining the bending moment vs. curvature relationship for flexible risers. A comparison between the dynamic response predicted with the proposed finite element and the one obtained with the traditional approach was performed.

scholarly journals The Responses of an End-Bearing Pile to Adjacent Multipropped Excavation: 3D Numerical Modelling

2019 ◽  
Vol 5 (3) ◽  
pp. 552 ◽  
Author(s):  
Dildar Ali Mangnejo ◽  
Naeem Mangi
Keyword(s):  
Soft Clay ◽  
High Stress ◽  
Three Dimensional ◽  
Bending Moment ◽  
Small Strain ◽  
Ground Movement ◽  
Stress Regime ◽  
Moment Capacity ◽  
Negative Skin Friction ◽  
End Bearing Pile

It is well recognised that superstructure load is transferred to surrounding soil through piled foundation. Consequently, the high stress regime (stress bulb) is generated surrounding of the pile. On the other hand, the excavation in the ground inevitably results in the ground movement due to induced-stress release. These excavations are sometimes inevitable to be constructed adjacent to existing piled foundations. This condition leads to a big challenge for engineers to assess and protect the integrity of piled foundation. This research presents three-dimensional coupled consolidation analyses (using clay hypoplastic constitutive model which takes account of small-strain stiffness) to investigate the responses of an end-bearing pile due to adjacent excavation at different depths in soft clay. The effects of excavation depths (i.e., formation level) relative to pile were investigated by simulating the excavation near the pile shaft (i.e., case S) and next to (case T). It was revealed that the maximum induced bending moment in the pile after completion of excavation in all the cases is much less than the pile bending moment capacity (i.e. 800 kNm). Comparing the induced deflection of the end-bearing pile in the case T, the pile deflection in case S is higher. Moreover the piles in cases of S and T were subjected to significant dragload due to negative skin friction.

3D numerical analysis of pile response due to soil movements induced by an adjacent deep excavation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tamir Amari ◽  
Mohamed Nabil Houhou
Keyword(s):  
Numerical Analysis ◽  
Parametric Study ◽  
Pile Group ◽  
Small Strain ◽  
Nonlinear Behaviour ◽  
Single Pile ◽  
Deep Excavation ◽  
Braced Excavation ◽  
Content Type ◽  
Pile Response

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.

scholarly journals Seismic analysis of the zaouiat ait mellal twin tunnels of Agadir motorway (Morocco)

2020 ◽  
Vol 150 ◽  
pp. 03001
Author(s):  
Abdelhay El Omari ◽  
Mimoun Chourak ◽  
Carlos Navvaro Ugena ◽  
Seif-Eddine Cherif ◽  
Mohamed Rougui ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Free Field ◽  
Bending Moment ◽  
Structural Elements ◽  
Underground Structures ◽  
Maximum Displacement ◽  
The Difference ◽  
The Stability ◽  
The One ◽  
Twin Tunnels

Underground structures, such as tunnels, are vital for ensuring all kinds of transportation; and being buried under the surface makes them exposed to soil dynamics. Added to the moderate seismic activity in Morocco, the stability of tunnels is put to the test. This paper examines the interaction between the ZAM (Zaouit Ait Mellal) twin tunnels between the cities of Marrakesh and Agadir, using the Difference Element Method provided by FLAC 2D software. The acceleration is introduced as the one related to the historic event of El centro 1940 with free-field boundary conditions in the numerical model, with three configurations: tunnel 1 without tunnel 2, tunnel 2 without tunnel 1 and tunnel 1 with tunnel 2. The results of the simulations indicate that the differences values of the maximum displacement, axial force and bending moment on structural elements are very noteworthy from the configuration of the tunnel (single) to the twin tunnels in order to prove the interaction between these latter under seismic loading.

scholarly journals Effects of Construction Sequences and Volume Loss on Perpendicularly Crossing Tunnels

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Yanwei Zang ◽  
Penglu Gan ◽  
Jia-jia Yan ◽  
Shiming Liu ◽  
Zihai Yan
Keyword(s):  
Urban Areas ◽  
Rapid Development ◽  
Three Dimensional ◽  
Ground Surface ◽  
Stress Transfer ◽  
Bending Moment ◽  
Small Strain ◽  
Research Attention ◽  
The Past ◽  
Three Dimensional Finite Element

The number of constructed tunnels has been gradually increasing for the past decades due to rapid development in urban areas. However, the soil-structure interaction problems arising from perpendicularly crossing tunnels attract relatively little research attention in the past. In this study, six three-dimensional finite element analyses were conducted to simulate tunnel excavation nearby a perpendicularly crossing existing tunnel, in an attempt to investigate the effects of construction sequences on cross-cutting tunnels. The hypoplastic constitutive model for sand is adopted in the numerical analysis to consider the soil small-strain stiffness. Computed results are presented and discussed in terms of ground surface settlement, displacement and deformation of the existing tunnel, and bending moment induced on the existing tunnel. The stress-transfer mechanism in soil nearby the existing tunnel due to tunnelling is also studied.

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