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.

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.

Elasto-Plastic Design of Piled Raft Foundation

2012 ◽  
Vol 446-449 ◽  
pp. 588-591
Author(s):  
Ai Hong Han ◽  
Hui Jun Zheng
Keyword(s):  
Small Diameter ◽  
Plastic Property ◽  
Plastic Design ◽  
Piled Raft ◽  
Pile Diameter ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Full Capacity ◽  
Pile Length ◽  
Better Than

When the loading sustained by the foundation is large, employing piled raft foundation is one of the best solutions. In the elasto-plastic design of piled raft, piles could improve the differential settlement and reduce raft thickness. As the raft sustains high earth and water pressures, by reducing the span length of raft and excavation depth, one can get economic design. Using elasto-plastic property of the pile is a better method to avoid increasing the pile length and pile diameter and making full capacity of the piled raft foundation in design compared to normal piled raft. With adoption of few small diameter piles, the raft thickness could be reduced significantly. This makes it much better than raft foundation.

3D Finite Element Analysis on Behaviour of Piled Raft Foundations

2014 ◽  
Vol 580-583 ◽  
pp. 3-8 ◽  
Author(s):  
Anhtuan Vu ◽  
Ducphong Pham ◽  
Tuonglai Nguyen ◽  
Yu He
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Element Analysis ◽  
3D Finite Element ◽  
3D Finite Element Analysis ◽  
Pile Spacing ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Pile Length

This paper highlights settlement behaviour of piled raft foundation by 3D finite element analysis through Plaxis 3D Foundation program. The effects of pile number, pile length, pile layout and pile spacing on the behaviour of piled raft foundation were studied. The numerical results show that: Piled raft foundation has much more efficency to reduce settlement than that of traditional raft foundation. The value of vertical defomation decreases as the result of the increase of pile number, pile length, pile spacing and vice versa. Pile layout has significant effect on both value and location of maximum settlement of piled raft foundation.

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.

Piled Raft Structure Finite Element Analysis of Composite Foundation Settlement in Da XI Passenger Dedicated Line

2014 ◽  
Vol 937 ◽  
pp. 438-443
Author(s):  
Xiao Tong Ma ◽  
Guang Long Liu
Keyword(s):  
Finite Element ◽  
Composite Foundation ◽  
Foundation Settlement ◽  
Pile Spacing ◽  
Finite Element Software ◽  
Piled Raft ◽  
Pile Diameter ◽  
Foundation Treatment ◽  
Pile Length ◽  
Passenger Dedicated Line

Composite foundation settlement of piled raft structure in Da Xi passenger dedicated line is analyzed by the large finite element software MIDAS/GTS and established calculation model of foundation treatment. The problem of pile-soil contact is highlighted in the trail and analyzes the settlement nephogram and pile-soil stress nephogram. On this basis the foundation settlement factors was analyzed systematically that focus on the elastic modulus of pile, pile spacing, pile diameter and pile length in foundation treatment, especially for the characteristics parameters of contact element. Result shows that increasing the pile modulus, pile diameter, pile length and decreasing the pile spacing is all conducive to reducing settlement. The best advice is got that the pile diameter should be not more than 0.5m, pile length not more than 27m and the pile spacing be around 2m.

Design of reinforcing piles to increase slope stability

1995 ◽  
Vol 32 (5) ◽  
pp. 808-818 ◽  
Author(s):  
Harry G. Poulos
Keyword(s):  
Shear Force ◽  
Soil Mechanics ◽  
Relative Depth ◽  
Soil Movement ◽  
Pile Diameter ◽  
Maximum Shear Force ◽  
Final Design ◽  
Length Step ◽  
Pile Interaction ◽  
Pile Length

This paper describes an approach for the design of piles to reinforce slopes, involving three main steps: (1) evaluating the shear force needed to increase the safety factor to the desired value; (2) evaluating the maximum shear force that each pile can provide to resist sliding of the potentially unstable portion of the slope; and (3) selection of the type and number of piles, and the most suitable location of these piles within the slope. For step 1, stability analyses can be used to assess the required additional shear force for stability. Step 2 involves the use of a computer analysis for the response of a pile to laterally moving soil. This analysis can be implemented via a computer program ERCAP, and enables the resisting shear force developed by the piles to be evaluated as a function of pile diameter and flexibility and the relative depth of the soil movement in relation to the pile length. Step (3) involves the use of engineering judgement in conjunction with the analysis results from steps 1 and 2. The paper describes the ERCAP analysis and the characteristics of pile behaviour it reveals. The application of the approach to a highway bypass problem in Newcastle, Australia, is described in detail. In the final design, a total of 64 bored piles 1.2 m in diameter were used over a total length of slope cutting of about 250 m. The pile lengths ranged between 6 and 12 m, with the spacings varying between 3.2 and 6.0 m. Key words : analysis, boundary element, piles, soil–pile interaction, slope stabilization, soil mechanics.

scholarly journals ESTIMATING THE INTERNAL FORCES OF RAFT IN PILED RAFT FOUNDATION FOR NORMAL AND GROUNDWATER PUMPING CONDITIONS: A CASE STUDY SOC TRANG PROVINCE, VIETNAM

2021 ◽  
Vol 1 (42) ◽  
pp. 86-93
Author(s):  
Hiep Van Huynh ◽  
Tri Huu Huynh ◽  
Truyen Gia Ngo ◽  
Tuan Van Tran
Keyword(s):  
Shear Force ◽  
Soft Soil ◽  
Groundwater Pumping ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Length Width ◽  
Internal Forces ◽  
Raft Foundations

Piled raft foundations are widely used in infrastructure built on soft soil to reduce the settlement and enhance bearing capacity. The raft can be used for basements and to share the load. In this paper, Poulos method, in which the raft was cut into many piled strips, was used as an analytical method. The study also used Plaxis2D and SAP 2000 to calculate internal forces for the raft in a piled raft foundation. A case of Vietcombank building with 10 floors and 1 basement, constructed on a soil profile in Soc Trang province, was studied. The piled raft with a 35m×19m×1m (length×width×thickness) raft and 28 piles were used for the analysis. Normaland groundwater pumping conditions were applied for the soil. The results showed that the maximum moment and shear force that occurred in the raft were affected when the groundwater pumping condition was applied to the model. The internal forces of the raft in the piled raft foundation for different conditions were captured,discussed, and presented in this paper.

scholarly journals Parametric Study on Unconnected Piled Raft Foundation Using Numerical Modelling

2020 ◽  
Vol 26 (5) ◽  
pp. 156-171
Author(s):  
Athraa Mohammed Jawad Alhassani ◽  
Ala Nasir Aljorany
Keyword(s):  
Axial Stress ◽  
Soil Layer ◽  
Structural Members ◽  
Element Analysis ◽  
Foundation Soil ◽  
High Rise ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Pile Length

Piled raft is commonly used as foundation for high rise buildings. The design concept of piled raft foundation is to minimize the number of piles, and to utilize the entire bearing capacity. High axial stresses are therefore, concentrated at the region of connection between the piles and raft. Recently, an alternative technique is proposed to disconnect the piles from the raft in a so called unconnected piled raft (UCPR) foundation, in which a compacted soil layer (cushion) beneath the raft, is usually introduced.  The piles of the new system are considered as reinforcement members for the subsoil rather than as structural members. In the current study, the behavior of unconnected piled rafts systems has been studied numerically by means of 3D Finite Element analysis via ABAQUS software. The numerical analysis was carried out to investigate the effect of thickness and stiffness of the cushion, pile length, stiffness of foundation soil, and stiffness of bearing soil on the performance of the unconnected piled raft. The results indicate that when unconnected piles are used, the axial stress along the pile is significantly reduced e.g. the axial stress at head of unconnected pile is decreased by 37.8% compared with that related to connected pile. It is also found that the stiffness and thickness of the cushion, and stiffness of foundation soil have considerable role on reduction the settlement.

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