scholarly journals Investigation of piled behaviour due to an adjacent excavation: 3D numerical modelling

2021 ◽  
Vol 9 (6) ◽  
pp. 683-689
Keyword(s):  
Numerical Study ◽  
Bending Moment ◽  
Hypoplastic Model ◽  
Engineering Research ◽  
Soil Movement ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Stress Changes ◽  
3D Numerical Modelling ◽  
Path Dependent

Zameer Ahmed Channaret al.,InternationalJournal of Emerging Trends in Engineering Research, 9(6), June 2021, 683–689683ABSTRACTIn congested cities, excavations are unavoidably constructed adjacent to high rising building supported by piled raft foundations which reduces differential settlements in the buildings. Since the excavations inevitably induce soil movement and stress changes in the ground, it may cause differential settlements to nearby piled raft foundation. In this numerical study, a 3D coupled consolidation numerical analysis (using a hypoplastic model, which considers strain dependent and path-dependent soil stiffness) was conducted to investigate a (2×2) piled raft responses to an adjacent 25-m deep excavation in saturated clay. The computed results have revealedthat the rate of piled raft settlement increased significantly beyond excavation stage h/He=0.5. This is because of the degradation of stiffness of clay with strain due to excavation-induced stress release. Differential settlement (i.e. tilting) was induced in the piled raft due to non-uniform stress release.Owing to separation of the raft from the ground due excavation, some of the working load was transferred to the four piles. The maximum positive bending moment was 200 kNm at Z/Lp=0.67. However, no any bending moment was induced in both the piles at the toes.

Issues on Design of Piled Raft Foundation

2018 ◽  
Vol 14 (1) ◽  
pp. 6057-6061 ◽  
Author(s):  
Padmanaban M S ◽  
J Sreerambabu
Keyword(s):  
Contact Area ◽  
Concrete Slab ◽  
Design Procedure ◽  
Bending Moment ◽  
Foundation Design ◽  
Detailed Review ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Influencing Parameters

A piled raft foundation consists of a thick concrete slab reinforced with steel which covers the entire contact area of the structure, in which the raft is supported by a group of piles or a number of individual piles. Bending moment on raft, differential and average settlement, pile and raft geometries are the influencing parameters of the piled raft foundation system. In this paper, a detailed review has been carried out on the issues on the raft foundation design. Also, the existing design procedure was explained.

scholarly journals 3D Numerical Modeling of Large Piled-Raft Foundation on Clayey Soils for Different Loadings and Pile-Raft Configurations

2020 ◽  
Vol 42 (1) ◽  
pp. 1-17
Author(s):  
Shivanand Mali ◽  
Baleshwar Singh
Keyword(s):  
Numerical Modeling ◽  
Soil Profile ◽  
Bending Moment ◽  
Load Sharing ◽  
3D Numerical Modeling ◽  
Interface Elements ◽  
Pile Spacing ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation

AbstractIn a piled-raft foundation, the interaction between structural elements and soil continuum can be simulated very precisely by numerical modeling. In the present study, 3D finite element model has been used to examine the settlement, load-sharing, bending moment, and shear force behavior of piled-raft foundation on different soil profiles for different load configurations and pile-raft configurations (PRCs). The model incorporates the pile-to-soil and raft-to-soil interactions by means of interface elements. The effect of parameters such as pile spacing and raft thickness are also studied. For any soil profile, larger pile spacing is observed to be more efficient in reducing the average settlement and enhancing the load-sharing coefficient. The smaller pile spacing is observed to be efficient in reducing the differential settlement. For any soil profile, the behavior of piled-raft foundation is significantly affected by the PRCs and load configurations. Furthermore, the raft thickness has significant effect on settlement, bending moment, and shears force. Thus, the results of the present study can be used as guidelines for analyzing and designing large piled-raft foundation.

scholarly journals Ground deformation mechanism due to deep excavation in sand: 3D numerical modelling

2021 ◽  
Vol 9 (6) ◽  
pp. 741-747
Keyword(s):  
Relative Density ◽  
Deformation Mechanism ◽  
Ground Deformation ◽  
Ground Movement ◽  
Soil Stiffness ◽  
Maximum Settlement ◽  
Hypoplastic Model ◽  
3D Numerical Modelling ◽  
Path Dependent ◽  
Underground Transportation

In densely built areas, development of underground transportation system often involves excavations for basement construction and cut-and-cover tunnels which are sometimes inevitable to be constructed adjacent to existing structure. Inadequate support systems have always been major concern as excessive ground movement induced during excavation could damage to neighbouring structure. A detailed parametric analysis of the ground deformation mechanism due to excavation with different depths in sand with different densities (Dr=30%, 50%, 70% and 90%) is presented. 3D finite element analyses were carried out using a hypoplastic model, which considers strain-dependent and path-dependent soil stiffness. The computed results have revealed that the maximum settlement decreased substantially when the excavation is carried out in the sand with higher relative density. This is because of reason that sand with higher relative density possesses higher stiffness. Moreover, the depth of the maximum settlement of the wall decreases as the sandbecome denser.The ground movement flow is towards excavation in retained side of the excavation. On the other hand the soil heave was induced below the formation level at excavation side. The maximum strain level of 2.4% was induced around the diaphragm wall.

Optimizing the Unconnected Piled Raft Foundation for Soft Clay Soils: Numerical Study

2020 ◽  
Vol 24 (4) ◽  
pp. 1095-1102 ◽  
Author(s):  
Walid El Kamash ◽  
Hany El Naggar ◽  
Marwa Nabil ◽  
Alaa Ata
Keyword(s):  
Numerical Study ◽  
Soft Clay ◽  
Clay Soils ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation

scholarly journals Assessing the effect of governing parameters of bearing capacity determination of small piled rafts on clay soil

2021 ◽  
Vol 14 (22) ◽  
Author(s):  
Shivanand Mali ◽  
Baleshwar Singh
Keyword(s):  
Shear Force ◽  
Bending Moment ◽  
Pile Spacing ◽  
Piled Raft ◽  
Pile Diameter ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Maximum Shear Force ◽  
Settlement Ratio ◽  
Pile Length

Abstract In the present study, a small piled raft foundation has been simulated numerically through PLAXIS 3-D software. The objective of this study was to investigate the effect of governing parameters such as pile length, pile spacing, pile diameter, and number of piles on the settlement and load-bearing behavior of piled raft, so as to achieve the optimum design for small piled raft configurations. An optimized design of a piled raft is defined as a design with allowable center and differential settlements and satisfactory bearing behavior for a given raft geometry and loading. The results indicated that, with increase in pile length, pile spacing, pile diameter, and number of piles, both the center settlement ratio and differential settlement ratio decreased. The load-bearing capacity of piled raft increased with increase in pile length, pile spacing, pile diameter, and number of piles. Furthermore, the percentage load carried by the piles increased as the pile length, pile spacing, pile diameter, and number of piles increased. The bending moment and shear force in corner pile are noted to be more, and they decreased towards the center pile. With increase in pile length, the maximum raft bending moment decreased, whereas the maximum shear force in the raft increased. Further, with increase in pile spacing, pile diameter, and number of piles, the maximum bending moment and maximum shear force in the raft increased. The optimum parameters for the piled raft foundation can be selected efficiently with the consideration of maximum bending moment and maximum shear force while designing the piled raft foundation. Thus, the results of this study can be used as guidelines for achieving optimum design for small piled raft foundation.

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