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.

AN ESTIMATING METHOD FOR LATERAL BEHAVIOR OF PILED-RAFT FOUNDATION

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Haruyuki Yamamoto ◽  
He Huang
Keyword(s):  
Ground Surface ◽  
Surface Displacement ◽  
Lateral Loading ◽  
Location Factors ◽  
Location Factor ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Cone Model ◽  
Raft Foundations

Some simplified design methods were proposed to predict behavior of lateral loaded piled-raft foundations on homogenous soil. One of them is the cone model method. However, only one average solution of pile behavior can be given by this method. It can’t evaluate the location factors of piles. Therefore, this paper describes a new simplified method to predict behavior of lateral loaded piled raft foundations covering the location factor of piles. At first, ground surface displacement is derived theoretically by Cerutti’s solution, then assuming that the raft foundation has rigid stiffness, these displacements are the same to calculation lateral loading distribution. Second, the ground displacement where pile placed could be estimated under calculated lateral loading. Third, the piles behavior are evaluated based on these lateral ground displacements. In addition, 3-D FEM numerical analysis were performed to compared with these solutions.

scholarly journals Behaviour of Load-Bearing Components of a Cushioned Composite Piled Raft Foundation Under Axial Loading

2014 ◽  
Vol 22 (4) ◽  
pp. 25-34 ◽  
Author(s):  
V. J. Sharma ◽  
S. A. Vasanvala ◽  
C. H. Solanki
Keyword(s):  
Soil Profile ◽  
Axial Loading ◽  
Load Bearing ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
The World ◽  
Raft Foundations ◽  
Flexible Pile

Abstract In the last decade piled raft foundations have been widely used around the world as intermediate foundation systems between piles and rafts to control the settlement of foundations. However, when those piles are structurally connected to rafts, relatively high axial stresses develop in relatively small numbers of piles, which are often designed to fully mobilize their geotechnical capacities. To avoid a concentration of stress at the head of piles in a traditional piled raft foundation, the raft is disconnected from the piles, and a cushion is introduced between them. Also, to tackle an unfavourable soil profile for a piled raft foundation, the conventional piled raft has been modified into a cushioned composite piled raft foundation, where piles of different materials are used. In the current study the behavior of cushioned foundation components, which transfer the load from the structure to the subsoil, are analyzed in detail, i.e., the thickness of the raft, the length of a long pile and the modulus of a flexible pile.

scholarly journals A Review on the Behaviour of Combined Stone Columns and Pile Foundations in Soft Soils when Placed under Rigid Raft Foundation

2021 ◽  
Vol 16 ◽  
pp. 1-8
Author(s):  
Danish Ahmed ◽  
Siti Noor Linda Bt Taib ◽  
Tahar Ayadat ◽  
Alsidqi Hasan
Keyword(s):  
Ground Improvement ◽  
Soft Soil ◽  
Research Work ◽  
Stone Columns ◽  
Attractive Alternative ◽  
Soft Soils ◽  
Ongoing Research ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Raft Foundations

In the last few decades, it has been observed that raft foundations are very commonly used as a foundation solution for moderate to high rise structures either by resting on stone columns or on piles in soft soils. It is believed that, combining stone columns and piles in one foundation system is the more suitable foundation for medium rise structures. The combined foundation system provides a superior and more economical alternative to pile, and a more attractive alternative to stone columns in respect to ground improvement. This paper presents the review of existing studies reported in the literature in the last two decades about the behaviour of stone columns under raft foundations and piled raft foundation in soft soil, notably the failure mechanism and the bearing capacity. Also, a limited work from the literature concerning the performance of combined (pile/stone columns) foundation system in soft soil is comprised. Furthermore, very extensive ongoing research work regarding the investigation and study on the performance of combined (pile/stone columns) foundation system in soft soils is discussed. The main goals and methodology to study the performance of the combined (pile/stone columns) foundation systems in soft soil are also addressed.

scholarly journals Experimental Investigation for Effects of Mini-piles on the Structural Response of Raft Foundations

2019 ◽  
Vol 5 (5) ◽  
pp. 1084-1098
Author(s):  
Huda Hussein Ahmed ◽  
Salah Rohaima Al-Zaidee
Keyword(s):  
Structural Response ◽  
Cost Effective ◽  
Bending Moments ◽  
Historical Structures ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Significant Difference ◽  
Scale Down ◽  
Raft Foundations

Mini-piles made their debut as a cost-effective way to stabilize the historical structures. Recently, mini-piles have increased in popularity all over the world and are being used for bridges, buildings, slope stability, antenna towers, and residential construction. This paper presents the preparing, executing, data acquisition, and result presentation for an experimental work concerns with five scale-down mini-piled raft foundation models. All models were prepared to study the effectiveness of the mini-piled raft foundation in reducing the settlement and the bending moments. Five tests have been achieved. The reference first test includes a raft foundation with 15mm thickness. Second, third, and fourth tests are mini-piled raft foundations with five mini-piles and with thicknesses of 15 mm, 10 mm, and 8mm respectively. Finally, the fifth test dealt with a single mini-pile 178mm in length and 6mm in diameter. It has been adopted to investigate the reference behavior of the single mini-pile. When they were used, the piles have 42 mm center to center distances. A scale-down factor of , a sandy soil with with  of , and relative density of 60% have been considered in all tests. Test results indicated a 45% decrease in settlement for 15mm mini-piled raft foundation comparing with the reference 15mm raft foundation. Moreover, there is no significant difference in settlement between 15mm mini-piled raft foundation comparing with the 10mm and 8mm thick mini-piled raft foundations. Regarding to the bending moments, they decrease at the mid and edge of the 15mm mini-piled raft foundation comparing to those of the reference raft foundation. It has also been noted that the moments are inversely proportional to the thickness of the piled raft foundations. With respect to the mini-piles, it has been found that most of the pile axial loads are transferred to the underneath soil through friction and this friction increases as the raft thickness decreases.

scholarly journals Influence of Variable Rigidity Design of Piled Raft Foundation on Seismic Performance of Buildings

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Yunfei Xie ◽  
Shichun Chi ◽  
Maohua Wang
Keyword(s):  
Seismic Performance ◽  
Nuclear Power ◽  
Soft Soil ◽  
Optimized Design ◽  
Variable Rigidity ◽  
Structure Interaction ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Pile Arrangement ◽  
Raft Foundations

In order to reduce the costs and improve the overall performance of building systems, the static optimized design with variable rigidity of piled raft foundations has been widely used in recent years. Variable rigidity design of piled raft foundations that support midrise buildings in high-risk seismic zones can alter the dynamic characteristics of the soil-pile-structure system during an earthquake due to soil-pile-structure interaction. To investigate these aspects, a nuclear power plant sitting on multilayered soil is simulated numerically. The paper describes a numerical modeling technique for the simulation of complex seismic soil-pile-structure interaction phenomena. It was observed that the total shear force on top of the piles and the rocking of the raft are reduced after optimization, whereas the displacement of the superstructure is nearly unaffected. The findings of this study can help engineers select a correct pile arrangement when considering the seismic performance of a building sitting on soft soil.

ANALYTICAL STUDY OF PILED-RAFT FOUNDATIONS CONSIDERING PLAN GEOMETRY AND NONLINEAR BEHAVIOR OF GROUND

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Haruyuki Yamamoto ◽  
He Huang
Keyword(s):  
Pile Foundation ◽  
Analytical Study ◽  
Nonlinear Behavior ◽  
Theory Of Elasticity ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Raft Foundations

The piled-raft foundation transfers loading to the ground by the raft and the piles together. It was proposed in the 1970s and is widely used for controlling settlement. Simplified estimate equations are used for the primary design. Equations by Randolph can presume the settlement stiffness of the piled-raft foundation and the loading share ratio from the settlement stiffness of raft and pile foundation. Raft foundations not only have regular shapes as squares, they also have some particular shape like triangular or L-plan. Therefore, different shape plans are discussed in this paper to verify the applicability of these equations. Also, these equations are proposed based on a theory of elasticity. However, the ground has nonlinear behavior even under small loading levels, so estimating the applicability of these equations when the ground behaves nonlinearly is necessary.

scholarly journals Analysis of Piled Raft Foundation on Soft Soil Using PLAXIS 2D

2015 ◽  
Vol 125 ◽  
pp. 363-367 ◽  
Author(s):  
Paravita Sri Wulandari ◽  
Daniel Tjandra
Keyword(s):  
Soft Soil ◽  
Piled Raft ◽  
Piled Raft Foundation ◽  
Raft Foundation
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