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

Shivanand Mali; Baleshwar Singh

doi:10.2478/sgem-2019-0026

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

Studia Geotechnica et Mechanica

Volume 42 (2020): Issue 1 (April 2020)

By: Shivanand Mali and Baleshwar Singh

Open Access

|Mar 2020

Figures & Tables

**(a)** Typical finite element mesh used in the parametric study. **(b)** Plan view (quarter of the piled raft)

A 10-node tetrahedral element (Brinkgreve et al. 2015)

Table 1

Material properties used in the validation (Sinha and Hanna 2016)

Material	Properties	Unit	Value
Soil	Young’s modulus, E_s	MPa	54
	Poisson’s ratio, ν_s	-	0.15
	Unit weight, γ	kPa	19
	Angle of internal friction, φ	°	20
Raft	Young’s modulus, E_r	GPa	34
Pile	Young’s modulus, E_p	GPa	25
Pile	Poisson’s ratio, ν_p	-	0.2

Comparison of load settlement behavior of the present study with the results of Sinha and Hanna (2016)

Table 2

Material properties used in the parametric analysis

Material	Properties	Unit	Value
Soil	Unsaturated unit weight, γ_unsat	kN/m³	16
	Young’s modulus, E_s	MPa	25 (Soft clay)
	Young’s modulus, E_s	MPa	82 (Stiff clay)
	Poisson’s ratio, ν_s	-	0.495
	Angle of internal friction, φ	°	0
	Undrained cohesion	kPa	25 (Soft clay)
	Undrained cohesion	kPa	80 (Stiff clay)
Raft	Young’s modulus, E_r	GPa	25
Raft	Poisson’s ratio, ν_r	-	0.25
Pile	Young’s modulus, E_p	GPa	25
Pile	Poisson’s ratio, ν_p	-	0.25

Table 3

Geometric configurations of pile-raft model for parametric analysis

Parameters	Unit	Value
Raft width, B_r	m	45
Raft width, L_r	m	45
Raft thickness, t_r	m	0.5, 1, 1.5, 2^*
Number of piles	-	49
Pile length, L_p	m	30^*
Pile spacing, S_p	m	3^*, 4, 5, 6, 7
Width of pile group, B_g (Corresponding to each S_p)	m	19, 25, 31, 37, 43
Pile diameter, d_p	m	1

* Indicates standard value if not varied.

**(a)** Location of column and **(b)** top view of pile-raft configurations

Different configurations used in the parametric study: (a) load configurations (LCs) and (b) pile-raft configurations (PRCs)

Table 4

Pile lengths used for different pile-raft configurations

Name and no. of piles, N_p	Pile length, L_p (m)

	PRC with uniform pile lengths	PRC with “W”-shaped pile lengths	PRC with “V”-shaped pile lengths
P₁ (1 pile)	30	L_1W = 24.46	L_1V = 37.19
P₂–P₉ (8 piles)		L_2–9W = 1.1 L_1W = 26.91	L_2–9V = L_1V/1.1 = 33.81
P₁₀–P₂₅ (16 piles)		L_10–25W = 1.1 L_2–9W = 29.60	L_10–25V = L_2–9V/1.1 =30.74
P₂₆–P₄₉ (24 piles)		L_26–49W = 1.1 L_10–25W = 32.56	L_26–49V = L_10–25V/1.1 =27.94

Effect of pile spacing on the average settlement for different pile-raft configurations: (a) soft clay and (b) stiff clay

Effect of pile spacing on differential settlement for different pile-raft configurations: **(a)** soft clay and **(b)** stiff clay

Table 5

Center and corner settlement for different pile-raft configurations at different pile spacings

Pile-raft configurations	Pile spacing, S_p (m)	Settlement in soft clay soil profile (mm)			Settlement in stiff clay soil profile (mm)

		W_center	W_corner	W_diff	W_center	W_corner	W_diff
PRC1(a)	3	490	474	16	160	147	41
PRC1(b)		916	891	25	157	117	40
PRC1(c)		1135	1125	10	158	119	39
PRC1(a)	7	211	121	90	144	72	72
PRC1(b)		232	116	116	150	68	82
PRC1(c)		243	162	81	139	77	62

Effect of pile spacing on load-sharing coefficient for different pile-raft configurations **(a)** soft clay and **(b)** stiff clay

Table 6

Load carried by piles in different pile-raft configurations at different pile spacings

Pile-raft configurations	Pile spacing, S_p (m)	Soft clay: load-carried by piles, R_pile (kN)			Stiff clay: load-carried by piles, R_pile (kN)

		R_center	R_edge	R_corner	R_center	R_edge	R_corner
PRC1(a)	3	226	2076	4434	565	3010	5854
PRC1(b)		431	3125	5597	650	3640	6723
PRC1(c)		494	1272	2765	1593	1474	3360
PRC1(a)	7	6721	7036	8579	6221	6388	5031
PRC1(b)		4890	7836	9105	4728	6879	5102
PRC1(c)		7376	6309	8240	7222	5751	4799

Effect of pile spacing on maximum bending moment for different pile-raft configurations **(a)** soft clay and **(b)** stiff clay

Effect of pile spacing on maximum shear force for different pile-raft configurations **(a)** soft clay and **(b)** stiff clay

Combined effect of raft thickness and pile spacing on (a) average settlement and (b) differential settlement for PRC2 (c)

Combined effect of raft thickness and pile spacing on load-sharing coefficient for PRC2(c)

Combined effect of raft thickness and pile spacing on (a) maximum bending moment and (b) maximum shear force for PRC2(c)

Effect of pile spacing on pile head settlement

**(a)** Effect of pile spacing on pile axial load and **(b)** bending in different piles

Effect of pile spacing on maximum bending moment in piles

References

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DOI: https://doi.org/10.2478/sgem-2019-0026 | Journal eISSN: 2083-831X (formerly 0137-124X) | Journal ISSN: 0137-6365

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Language: English

Page range: 1 - 17

Submitted on: Dec 3, 2018

Accepted on: Aug 21, 2019

Published on: Mar 19, 2020

Published by: Wroclaw University of Science and Technology

In partnership with: Paradigm Publishing Services

Keywords:

Pile-raft configurations

Related subjects:

Physics,

Mechanics and fluid dynamics

© 2020 Shivanand Mali, Baleshwar Singh, published by Wroclaw University of Science and Technology
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 42 (2020): Issue 1 (April 2020)

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

Figures & Tables

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Table 6

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