Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Clayey Soils


Behavior of Experimental Model of Piled Raft Foundations on Clayey Soils

Mahmoud AL-Qaissy; Hussein H. Karim; Mudhafar K. Hameedi

Engineering and Technology Journal, 2013, Volume 31, Issue 20, Pages 288-408

Piled raft foundations are a geotechnical composite construction consisting of three elements: piles, raft and soil. In the design of piled rafts, the load is assumed to be shared between the piles and the raft. Therefore, this may improve the ultimate load capacity and reduce settlements in a very economic way as compared with the traditional foundation concepts. Due to the development of structures that use piled rafts as a foundation system, an extensive experimental study was performed by two different scale models with the same L/Dp (Embedment length to pile diameter ratio) and L/Br (Embedded length to raft width ratio Br) to achieve the scale effect and plane stress condition for the large scale model and plane strain condition for the small scale model. The load carrying capacity of the piles and raft have been studied and presented as load-settlement illustrations. From a comparison between the two models of the experimental work, it is found that the effect of scale cause an increase in carrying load of piled raft with increasing the number of piles. It was found that the percentage of the load carried by raft to the total applied load of the experimental model in the case of four piles with raft is ranged between 60.6 - 64.8 %.

Numerical Analysis of Piled Raft Foundation on Clayey Soil

Hussein H. Karim; Mahmoud R. AL-Qaissy; Mudhafar K. Hameedi

Engineering and Technology Journal, 2013, Volume 31, Issue 7, Pages 1297-1312

The piled raft foundations allow an increase in the load capacity and reduction of settlements in a very economic way as compared with the traditional foundation concepts. Due to the development of structures that use piled rafts as a foundation system, an extensive numerical modeling study was performed considering different factors and conditions. This study highlights the percentage ratio of bearing loads between the pile and the pile cap (raft). Present modeling results obtained by computer program (Plaxis 3D Foundation V 1.1) have been verified with an experimental work of the same problem using the same configuration but extended to include 8 and 16 piles with raft for different soil layers. In addition, a comparison of the present results is achieved with another a theoretical study using the program (Ansys). The finite element method through Plaxis program evaluates the effect of parameter on the load-settlement behavior of the piled raft foundation. The effect of spacing between piles on the load-settlement behavior of the piled raft foundation was also studied. The percentage of the load carried by piles to the total applied load of the numerical model for case sixteen piles with raft is around 42%. The contribution to carry the load of piles relative to the total load is decrease with the increase of the spacing to diameter ratio. The percentage of the load carrying for piled raft for the case of two piles with raft only decreases about 23% when the spacing between piles increases from 3 to 10 times pile diameters.