Recent Studies on Piled-Raft Foundation: State of Art

JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING RECENT STUDIES ON PILED-RAFT FOUNDATION: STATE OF ART

1V.J.SHARMA, 2 S.A.VASANVALA, 3C.H.SOLANKI

1, 2, 3 Applied Mechanics Department, Sardar Vallabhai National Institute of Technology, Ichchhanath, Surat-7, Gujarat,India.

[email protected]

ABSTRACT : Due to increase of civilization in recent decades the demand of land for construction purpose has increased exponentially. As most of the time site available consists of weak subsoil conditions, piled raft foundation has been preferred on large scale due its efficiency of carrying high vertical loads within the permissible settlement limits and cost effectiveness compared to pile foundation system. This paper presents the brief review of various studies on piled-raft foundation in last decade. The paper also reveals latest modification done in conventional piled-raft as per site conditions and loading criteria.

Keywords: Differential Settlement, Total Settlement, Finite Element Method, Non-Identical Piles, Composite Piled-Raft, Viscohypoplastic

1. INTRODUCTION design of foundation system. This paper presents In traditional foundation design, it was customary to review of various studies carried out on piled-raft consider first the use of shallow foundation such as a foundation in clayey soil, sandy soil and weathered raft (possibly after some ground-improvement rocks. Various researchers have worked on piled–raft methodology performed). If it was not adequate, deep foundation system in clayey soil. Their work includes foundation such as a fully piled foundation was used study related to bearing behavior, composite system, instead. In the former, it was assumed that load of non-linear FEM analysis, piled-raft system with non- superstructure was transmitted to the underlying identical piles, etc. The Studies related to sandy soil ground directly by the raft. In the latter, the entire includes separate analysis of pile and raft, case design loads were assumed to be carried by the piles studies and use of FEM codes. Few works has been [24].In recent decades, another alternative carried out on weathered rock which includes paper intermediate between shallow and deep foundation, [3,7,10,and 25].Researcher [7] has carried out work what is called piled raft foundation or settlement in sand as well as weathered rock. reducing piles foundation, has been recognized by 2 .REVIEW civil engineers. The piled raft concept has been used The review includes various papers published in extensively in Europe and Asia. In this concept, piles various journals such as American society of civil are provided to control settlement rather than carry engineering, Proceedings of the 17th International the entire load. Piled raft foundation has been proved Conference on Soil Mechanics and Geotechnical to be an economical way to improve the Engineering ,Proceedings of ICE , etc .They have serviceability of foundation performance by reducing been grouped into major areas as: settlement to acceptable levels. The favorable 1. Study of pile raft system in clay application of piled raft occurs when the raft has 2. Study of pile raft system in sand and adequate loading capacities, but the settlement or weathered rock differential settlement exceed allowable values. 2.1 Study of pile raft system in clay : Conversely, the unfavorable situations for piled raft In situations where a raft foundation alone does not include soil profiles containing soft clays near the satisfy the design requirements, it may be possible to surface, soft compressible layers at relatively shallow enhance the performance of the raft by the addition of depths and some others [24]. In the unfavorable piles. The use of a limited number of piles, cases, the raft might not be able to provide significant strategically located, may improve both the ultimate loading capacity, or long-term settlement of the load capacity and the settlement and differential compressible underlying layers might reduce the settlement performance of the raft. The study on contribution of raft to the long-term stiffness of design of piled-raft system in clayey soils have been foundation. As we know piled-raft foundation system carried by [25, 15, 32, 31, 27, 28 19, 22 and 12].The is applied in weak subsoil conditions where chances design of piled raft system involves basically bearing of foundation settlement play vital and major role in capacity of supporting subsoil and permissible

ISSN: 0975 – 6744| NOV 10 TO OCT 11 | Volume 1, Issue 2 Page 38 JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING allowable total and differential settlements. Poulos found following reasons for use of the 3D Finite H.G. [25] had given outline of simplified method of Element Method (FEM): (1) the problem is so carrying out a preliminary feasibility study and complex that simplified methods cannot model the design of a piled raft system. The analysis is problem correctly; and (2) codes for the FEM are programmed via a spreadsheet program or a available, powerful, and capable of being run on the mathematical program such a MATHCAD. The personal computer. Comparisons were made between approach gives a reasonable estimate of the order of experimental and analytical results for two piled –raft the magnitude of settlement and differential foundations resting on stiff clay and the FEM has settlement of foundation when applied to case study shown to yield excellent results for the cases of piled raft on stiff clay and series of centrifuge tests analyzed .Oh E.Y.N etal. [22] have carried out on reconstituted soil. Liew S. S etal [15] have numerical analysis of un-piled raft and piled raft on designed and presented instrumentation results of two different soil conditions. The analysis was reinforcement concrete piled raft supporting 2500Ton carried out in two case studies with three typical load oil storage tanks on a very soft alluvial clayey soil of intensities of serviceability load. The subsoil was about 40m thick in Riau Province of Sumatra, modeled as linear elastic materials, raft as beam Indonesia. The design concept has been validated element and piles as element with shear and normal with the results of instrumentation Seo Y.K etal [32] coupling springs. For case study 1 with sandy soil have proposed design charts of piled raft foundations condition maximum settlement of piled raft depends on soft clay. The design charts were first presented on piles spacing and number of piles. For case study for the evaluation of both bearing capacity and total 2 with clayey subsoil, the settlement of un-piled raft settlement in the raft alone foundation system. Load was similar for different raft thickness .Raft thickness settlement relationship curves are used to evaluate the was found to have obvious effect on differential ultimate soil bearing capacity. The total settlement is settlement. The settlement of piled raft at piled area evaluated by applying various traditional safety showed a bowl shape settlement pattern and edge of factors of the uniformly distributed loads. Then, the the raft strip showed a downward deviation from parametric studies were carried out for the piled raft the settlement bowl. Lee J H.etal [12] has conducted foundation system. In the numerical analyses, elasto- series of 3D elasto-plastic finite element analyses to plastic finite elements models are used to present the investigate the bearing behavior of a square piled raft foundation response and the design charts, which subjected to vertical loading. In this study, the main enable the determination of the raft size and pile characteristic of these analyses was to permit soil slip length and spacing of piles. Sanctis L.D etal. [31] has at the pile–soil interface. Pile positions, pile number, proposed a simple design criterion to evaluate the pile length and loading distributions on the raft were ultimate vertical load of a piled raft as a function of varied, and the effects of pile–soil slip, pile its component capacities, which can be simply geometries and loading types were examined. evaluated by the conventional bearing capacity Furthermore, the proportion of load sharing of the theories. A broad parametric study is carried out raft and piles at the ultimate state and the relationship using 3D FEM analysis to define the failure load between the settlement and overall factor of safety coefficients accounting for the interaction between was evaluated. The results show that the use of a the raft and the pile group at failure. Also a guideline limited number of piles, strategically located, might has been given to assess the factor of safety of improve both bearing capacity and the settlement vertically loaded piled raft. As per Meisam Rabiebi performance of the raft. The work related to piled- [27] the maximum bending moment in raft increases raft foundation resting on over-consolidated clay was with increase raft thickness, decrease pile number carried out by [8, 29, 30], which includes numerical and decrease in pile length. Central and differential study of piled-raft foundation behavior and settlement decreases with increase raft thickness and comparison with field measured results. Reul O.etal uniform increase in pile length. Further Meisam [30] carried out comparisons of in-situ Rabiei [28] used a computer program ELPLA and measurements and numerical analyses for three found that pile configuration and load distribution piled raft foundations on over-consolidated clay are very important and effective in piled raft between overall settlement , differential settlement settlement , maximum moment and pile bearing and load carried by piles by back analysis. Three factor. Three basic pile configurations and three load main performance indicators of the piled raft were distribution types were considered. Pile configuration proposed: the proportion of load carried by the 1 has the pile uniformly distributed under whole raft piles,and the maximum settlement and maximum area. Pile configuration 2 has piles under central differential settlement, both as a proportion of the area of the raft as well as under the edge of the raft. corresponding quantity for an unpiled raft In pile configuration 3 the piles are placed only in the foundation. The last indicator suggests that improved central area of the raft, the detail is shown in fig.1 . layout of the pile support can lead to a reduction both Novak L.J etal [19] carried out analysis of pile-raft in the maximum differential settlement and in the foundations with 3D finite-element method .They overall quantity of piles. .

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Figure 1. Model configuration and properties used in the analysis the long piles made of relatively rigid materials were used to reduce the settlements and the cushion Garcia F etal [8] had applied viscohypo plastic model to the case history of piled raft foundation- Messeturm tower in Frankfurt beneath the raft was used to redistribute and adjust Germany with 3D FEM analysis with ABAQUS the stress ratio of piles to subsoil. Researchers [13, and the user subroutine UMAT developed by A. 41, 14, 40] had carried out rigorous analysis on Niemunis and the geotechnical group of the CPRF system .Liang F.Y. etal [13] have carried out Karlsruhe university in Germany. The calculated numerical analysis of composite piled raft with results are compared with the in situ measurements cushion subjected to vertical load. Influencing with the purpose to verify the viscohypoplastic law factors such as ratio of length to diameter and in a boundary value problem. It was found that elastic moduli of piles as well as thickness and viscohypoplastic model can predict with good level elastic modulus of cushion were studied in details. of agreement the behavior of a piled raft Load-sharing ratios of piles and subsoil as well as foundation. Reul O. [29] has carried out numerical foundation settlement were also investigated. study of bearing behavior of piled rafts in Zheng J.J. etal [41] carried out 3D non-linear finite overconsolidated clay. It is shown that the element modeling of composite foundation formed interaction between piles and rafts is a major by Cement-Flyash-Gravel-lime piles which is a influence on bearing capacity of piled-raft widely used ground improvement technique. A foundation. CFG–lime multi-pile composite foundation is a To mobilize shallow soil in coastal areas to new concept utilizing CFG and lime piles as shown participate in the interaction of piled raft foundation in fig 2. The parameters studied include the length sufficiently, the researchers extended the concept of and diameter of piles and the thickness of the piled raft to a new type of foundation named cushion. The stress distribution beneath the composite piled raft. In the system of composite composite foundation, the influence of the cushion piled raft, the short piles made of flexible materials on load-settlement behavior, and the ratio of were used to strengthen the shallow soft soil, while stresses in the piles to those in the subsoil are also studied. The results show that settlement is much

ISSN: 0975 – 6744| NOV 10 TO OCT 11 | Volume 1, Issue 2 Page 40 JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING more significantly affected by the length and foundation diameter of the CFG pile rather than that of the lime pile, thus CFG pile acts as a settlement- reducing pile. On the other hand, the load distribution between piles and subsoil is significantly affected by the cushion thickness. Optimization of composite piled raft foundation with varied rigidity of cushion was carried out by Liang F.etal [14 ].The analysis model of piled raft foundation was set up using the fictitious pile method , and Fredholm’s integral equations of the second kind were deduced to solve the problems .By simulating the cushion with wrinkle springs , the effect of cushion was taken into consideration. The method is suitable to analyze the foundation under working loads and could be Figure 3. Finite element discretization for piled- applied to solve problems of different rigidities of raft piles and cushion. ZHAO M.H.etal [40 ] have carried out settlement calculation for long –short A windows based general-purpose finite element composite piled raft foundation.Based on the shear program (AMPS) was used to carry out the deformation method,the Mylonakis and gazetas analyses.A suitable nonlinear model is used to model was introduced . Considering the effects model the soil behavior ,and contact interfaces are of cushion , the flexible factors of interaction included to study the interaction between soil and were provided.Then the settlement calculation piles and between soil and slab .Two piled-raft for long-short composite piled raft foundation system were analyzed. It was found that the was developed. The non-linear analyses of piled- contribution of the pile tip in the resistance tends to raft foundation have been interesting area of study increase as the deformation increases.Non-linear for many researchers which include [16, 17, 37, 33, finite element analysis of piled-raft foundation and 4].Maharaj D.K etal [16] worked on non-linear resting on layers of soil having different stiffness finite element analysis of piled –raft foundation have been done by [33,4,5]. Small J.C.etal [33] has resting on clay soil layers .. In this study the raft developed a method of analysis for piled raft and piles are assumed to be linearly elastic and foundation where piles exhibits nonlinear load – Drucker-Prager criterion has been used to represent deflection behavior. The raft is analysed by finite soil as elasto-plastic material.Based on three- element methods, while the piles are treated as dimensional non-linear finite element analysis, it springs having a variable stiffness,so as to model was found that the addition of even a small number any non-linear behaviour. The soil is treated as an of piles increases the load-carrying capacity of a elastic medium that may consist of layers of soil raft foundation. The axial load distribution shows having different stiffnesses. The method has been that the piles reach their ultimate capacity earlier incorporated into the computer program GARP than the raft. Maharaj D.K. [17 ] continued his (General Analysis of Rafts with Piles). This work in non-linear finite element analysis of piled program is used to analyse a tall building that was raft foundation under the application of uniformly constructed on a piled raft foundation, and a distributed load .Fig 3 shown below gives finite comparison is made of the calculated and observed element discretization and boundary conditions behaviour. Chen J etal [4] has presented a nonlinear applied to pile raft foundation. Load settlement analysis method for simulating the interaction of curves of raft and piled raft foundation have been superstructure –pile-raft-soil system in layered provided for different raft and pile stiffness. soil.The flexibility coefficients of the pile-pile and Vásquez L.G etal [37] had carried out non-linear the pile-soil are deduced , the stiffness matrix of three-dimensional finite element analysis to the pile-soil system is established, and interaction estimate capacity of piled raft. equation of superstructure –pile-raft –soil system is formulated. The distribution of the settlement of the foundation ,which was large in the middle and small in the boundary and like a dish, was consistent with the measured data in field. Further using nonlinear analysis method and program of the interaction of superstructure-pile- raft-soil system in layered soil ,reaction force on pile head and displacement characteristic of raft of the piled raft foundation were analysed when Figure 2. Sketch of CFG –lime pile composite the thickness of the raft, spacing of piles ,length and

ISSN: 0975 – 6744| NOV 10 TO OCT 11 | Volume 1, Issue 2 Page 41 JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING diameter of piles were changed. Recently it has weathered rock conditions. The researchers [2, 18, been found that piled-rafts having non-identical and 34] have studied effect of piles and raft in a piles shows efficient performance, researchers piled-raft foundation system founded in sand [36,5,35,6] had worked in the field of piled-raft separately and find out the behavior of piled-raft with non-identical pile lengths.Tan Y.C etal [36] foundation as whole. Cao X.D etal [2 ] have carried has given a design approach in which foundation out study on behavior of model rafts resting on of medium rise building is designed using skin- disconnected piles which act as reinforcement in friction piles of different length with longer piles at base soil (sand in this case ) rather than structural the center and progressive shorter pile towards the element . By varying factors such as raft stiffness, edge.For detailed design of foundation two cases pile length, pile arrangement, and pile number, were considered.Case 1 considers overall results of the investigation indicate that structurally settlement behavior of foundation system to predict disconnected piles are effective in reducing the settlement profile for structural design .Meanwhile settlement and bending moment in model rafts. case 2 considers interaction between the pile-soil- Nemoto H.etal[18] have carried out series of structure (foundation raft) of foundation system to experimental and analytical study on the determine load distribution and local settlement of behaviors of model pile groups and model piled piles and also structuraldesign of raft to rafts in dry sand subjected to static vertical load complement case 1. The foundation system was and static cyclic horizontal load to establish an monitored and the results obtained showed that adequate analytical method and seismic design foundation system adopted performed satisfactory. method . An emphasis was placed on the Chow H.S.W etal [ 5] have used finite layer method influence of the connection condition between for the analysis of piled rafts with piles of different the pile head and raft on the behaviors of the lengths and diameters. The soil is divided into model foundations .The test apparatus including horizontal layers with different material properties model foundations , model ground , loading , and only vertical loads may be applied to the raft. measuring devices and test procedure were Interactions between raft-soil-pile are computed described in detail. Sonoda R.etal [34] has applied Comparisons of actual measurements and the simple conservative design approach for design of results of finite element calculations have shown foundation. As per design approach building and its that the finite layer method can provide reasonably foundation were constructed in sandy ground using accurate solutions. It is very easy to prepare data a reverse construction method. The main difference for the finite layer analysis as only the pile between a reverse construction method and a locations and properties need to be specified, and conventional construction method is that the piles the piles discretised into linear elements. This are cast in place and are partially loaded by the method is more efficient than the conventional superstructure early during the construction three-dimensional finite element analysis. Tan Y.C process. It is only later that the raft (mat etal [35] discussed methodology of a floating foundation) is constructed to combine with the piles piled raft foundation system consisting of non- to bear the full building load. To examine the identical piles with longer piles in central portion validity of the design method, settlements of the and progressively shorter piles towards edge for foundation were observed during construction. The medium rise building (5-storey) on soft clay.Two measured settlements were smaller than those major cases were considered for detail foundation predicted in the design stage, satisfying the design analysis and design. Case 1 of pile-soil-structure requirements for the building design. interaction was taken in consideration to determine In recent years analysis of piled-raft foundation in stress distribution, deformation and settlement of sandy subsoils using finite element code has raft and piles. Case 2 considers overall settlement increased exponentially. The researchers [23,22, 20, behavior of piled raft (immediate and consolidation 21, 1, 11, 42 and 9] had carried out extensive settlement). Chow H.S.W [6] has done her Phd research in the same. They have used various finite thesis on behavior of piled rafts supported by element codes to incorporate the exact field non-identical piles examined by use of computer conditions.Paranmoyes etal [ 23] have illustrated program APRILS based on finite layer and finite the process of design of a piled raft foundation for a element methods.The finite layer method is used large residential development using a three stage for analysis of layered soil system. This method can procedure, consisting of an initial assessment of the be applied different shape of loadings and has feasibility of the design, a middle stage of refining shown good agreement with the theoretical pile locations and depths, and a detailed design solutions.The FEM is used for analysis of raft and stage of assessing the behaviour of the foundation piles. Full interaction between raft, piles and soil is under various loading cases using GARP8 considered in the analysis. computer program. The utilization of a piled raft 2.2 Study of pile raft system on sand and foundation versus a conventional piled only weathered rock:This section of the paper deals foundation delivered the required serviceability with piled –raft foundation system in sandy soil and performance with regard to total and differential

ISSN: 0975 – 6744| NOV 10 TO OCT 11 | Volume 1, Issue 2 Page 42 JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING settlements while providing cost savings estimated copper concentrate store founded on reinforced to be of the order of 30% versus the original pile- concrete raft supported by 697 piles. The piles are only solution Oh E .Y. N.etal[20] have carried out fitted on a dense sand layer , but there are clay parametric study on piled raft foundation in sand layers of medium consistency along the shaft using numerical modeling with three typical load and below the support soil.Owing to this , the intensities of serviceability load. The maximum piles are subjected to negative skin friction , the settlement of the piled rafts depends on the pile raft has suffered important settlements , the spacing and the number of piles; while the raft structure has been damaged and the upper thickness does not have a significant effect. The conveyor belt has experienced problems.A 3-D increase in raft thickness reduces the differential finite element (FE) calculation has permitted settlement in the foundations. The raft-soil calculation of the displacements and stresses in the stiffness (Krs) is shown to influence the piles, raft and structure. A 3-D finite element (FE) differential settlement and has the largest influence. calculation has permitted calculation of the Oh E .Y. N.etal[21] have studied analysis of un- displacement and stresses in piles, raft and piled and piled raft foundations with sandy soil structure. conditions similar to those found in Surfers Paradise of Australia. For the unpiled raft, the normalized settlement parameter (IR) for the raft sizes of 8m×8m and 15m×15m ranged as 1.02-1.15, and 0.64-0.81 respectively. In the case of the piled raft with raft thicknesses of 0.25, 0.4,0.8, 1.5 and 3m, the corresponding maximum settlements are 64, 63.3, 62.6, 62.3 and 62.2 mm, and the bending moment values are 107, 160, 321, 446 and 485 kNm. The piles are 0.7m diameter and 16m length. Three values of intensity of loading as 215, 430 and 645kN/m2 were studied. Figure 4 illustrates the symmetric idealization of the piled raft problem. Baziar M.H etal [1] have investigated bearing Figure 5: Numerical model of pile-raft Foundation -settlement behavior of combined pile-raft under 1g physical test using FLAC-3D a) Total foundations on medium dense sand Numerical mesh b) pile raft mesh simulation was also carried out on the model test, using FLAC-3D, to show compatibility of the Ziaie-Moayed R.etal[42] have evaluated piled raft numerical analysis with the test.Fig 5. Shows foundations behavior with different dimensions of numerical model mesh for piled raft and its piles.element program. They found that piled raft surround soil in simulation of 1g physical test. foundation with different pile diameters may be a good solution to reduce total and differential settlements if the bottom layer is dense soil but if bottom layer is soft soil then in that case piled raft system with different pile lengths can control differential and total settlements. Giretti.D [ 9] has done Phd work in Modelling of Piled raft foundations in sand. The main aim of thesis was to highlight the effects of the raft–soil–pile interactions on the resistance sand. Researchers [38,39 and 7] have carried out work on case studies comparing the values of design settlement with the measured values after execution of the projects.Yamashita K etal [38] have studied a case history of design and performance of piled raft ` supporting a 162 m high residential tower.Field Figure 4: Finite element dealization of pile raft measurements were performed on settlement and system load sharing of a piled raft supporting a 162m high isolated residential tower from beginning of Obtained results showed very good accuracy of the construction to eight month after the end of numerical method used in this study as long as the construction.At eight months after the end of applied load does not exceed the working load, construction, the measured settlement was 24mm while the performance of numerical model was and the ratios of the load carried by the piles to relatively good for the loads beyond working load. the effective load were estimated to be 0.88-0.94, Justo J.L etal [11 ] have studied structure of a which were consistent with the design values of

ISSN: 0975 – 6744| NOV 10 TO OCT 11 | Volume 1, Issue 2 Page 43 JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING the foundation settlement and load sharing Geotechnical investigations were outlined along between raft and piles. Yamashita.K etal [39] have with effect of proposed tower on neighboring studied a case history of seven-storey building of structures, single-pile response and impact of piled raft on loose sand underlain by soft silt cyclic degradation were assessed. Numerical layers .In order to reduce consolidation settlement analyses was used to evaluate the overall piled of the soft silt and to cope with liquefiable loose raft response under various static and wind sand, a piled raft combined with gird –form loading combination as well as some techniques ground improvement was adopted. The design of were used to optimize the foundation design, the foundation was found appropriate by field including preliminary pile testing. measurements which concerned settlement ,axial 3. CONCLUSIONS forces of the piles and earth pressures and pore – Following conclusions can be drawn from the water pressure beneath the raft from the various research studies: beginning of construction to time about four  Piled-raft foundation can be successively years after the end of construction. El- applied in weak sub-soil conditions i.e. clayey, Mossoallamy Y. etal [7] have done general over sandy and weathered rock .Piled –raft foundation view on recent innovative applications (case proves to be cost effective compared to other type studies) of piled rafts in Germany on Frankfurt of foundation systems clay, Berlin sand and Marl and weathered rock for  Finite element method is most efficient highway bridges .The piled raft foundation provides method to analyze complex nature of piled-raft a new geotechnical concept not only for high rise foundation behavior in clay, sand and weathered buildings but also for residential buildings and rock. The composite piled-raft, piled-raft with non- bridges, which allow a high grade technical and identical piles, etc are the latest modification in economical optimization of construction. Any kind conventional piled-raft system and found to be of eccentric construction can be safely founded on efficient with respect to geological and loading soft to stiff clay and also on loose to medium 4. REFERENCES dense sand by appropriate location of piles [1] M.H Baziar, A Ghorbani, R Katzenbach. ,staggering the pile length and suitable pile Small-Scale Model Test and Three-Dimensional diameter .The number and length of piles, the pile Analysis of Pile-Raft Foundation on Medium- load share ,total bearing capacity of piled raft and Dense Sand. International Journal of Civil its settlement are main criteria that should be Engineering. Vol. 7, No. 3, pp 170-175, 2009. investigated during a feasibility study to check [2] X D Cao, H. Wang and M F the validity of piled raft. Sometimes geological Chang .Behavior of Model Rafts Resting on Pile- conditions at site consist of weathered rocks on Reinforced Sand, Journal of Geotechnical and which piled raft foundation has to be laid. Recently Geoenvironmental Engineering Vol. 130, No. 2, pp. high rise buildings are founded on weathered rock 129-138, 2004. especially in Middle east countries. This has lead to [3] M .TA Chaudhary. FEM modeling of a development of interest of group of researchers [3, large piled raft for settlement control in weak rock 7, 26, and 10] in field of piled- raft foundation on Engineering Structures 29, 2901–2907, 2007. weathered rocks. Chaudhary M.TA [ 3 ] have [4] J Chen, Y Chang and Y Zou. Key investigated application of a group of 1072 piles for engineering Materials (Volumes 400 - controlling settlement of an important and sensitive 402):Advances in Concrete and Structures, pp. 651- structure founded on weak rock.2D axi- 658 symmetrical and 3D finite element models were [5] H.S.W Chow and J.C Small. Behavior of employed to model the 9.0 m thick and 76 m Piled Rafts with Piles of Different Lengths and diameter circular raft, underlying soil/rock and a Diameters under Vertical Loading. Advances in mix of annular and orthogonal pile layout. Deep Foundations (GSP 132), 2005. Effectiveness of pile foundation in reducing [6] H.S.W Chow. Analysis of piled-raft settlement was assessed by comparing the results foundation with piles of different length and with the case of raft foundation alone. Poulos H.G diameter ,Phd Thesis, 2007. etal [26] have outlined the processes followed in [7] Y.El-Mossoallamy, B.Lutz and T.Richter. the design of the foundations for the Burj Dubai Innovative application of piled raft foundation to and the independent verification of the design. The optimize the design of high-rise buildings and maximum settlement predicted by ABAQUS for bridge foundations,10th International Conference the tower and podium foundation compares on piling and deep foundations, Amsterdam 2006. reasonably well with the maximum settlement [8] F.Garcia,A.Lizcano, and O.Reul estimated by the revised PIGS analysis carried out Viscohypoplastic Model Applied to the Case during the independent verification process. History of Piled Raft Foundation. Geotechnical Ibrahim K.etal [10] have carried out piled raft Engineering in the information Technology Age, foundation design analysis of Pentominium tower Atlanta,GA 1-6,(2006). in Dubai,UAE in local carbonate soils and rock.

ISSN: 0975 – 6744| NOV 10 TO OCT 11 | Volume 1, Issue 2 Page 44 JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING [9] D. Giretti .Modelling of piled raft Study on Piled Raft Foundation in Sand Using foundations in sand ,Phd thesis (2009) Numerical Modeling ,www.griffith.edu.au [10] K .Ibrahim, G Bunce and [21] E.Y. N Oh, M. Huang, C Surarak, R. C.Murrels.Foundation design for the Pentominium Adamec and A.S. Balsurbamaniam. Finite element tower in Dubai,UAE,Proceedings of ICE , Civil modeling for piled raft foundation in sand. Eleventh Engineering 162, pp 25–33, 2009. East Asia-Pacific Conference on Structural [11] J.L Justo, A .Jaramillo, M .Vazquez, E Engineering &Construction (EASEC-11). .Justo and M.T. Perez .The performance of piled “Building a Sustainable Environment” November raft foundations, Proceedings of the 17th 19-21, 2008, Taipei, Taiwan. international conference on Soil Mechanics and [22] E.Y.N Oh, D.G Lin., Q.M Bui. , M. Geotechnical Engineering (ICSMGE 2009): 1228- Huang, C.Surarak andA.S. Balasubramaniam 1231. Numerical analysis of piled raft foundation in [12] J Lee, Y .Kim, J .Sangseom Three- sandy and clayey soils.Proceedings of the 17th dimensional analysis of bearing behavior of International conference on Soil Mechanics and piled raft on soft clay. Computers and Geotechnical Engineering (ICSMGE 2009): 1159- GeotechnicsVolume 37 Issue 1-2, pp. 103-114 , 1162 2010, [23] Paranmoyes , H.G. Poulos , J.C. Small [13] F.Y. Liang, L.Z. Chen, X.G. Shi. and F. Badelow . Piled raft design process for a Numerical analysis of composite piled raft with high-rise building on the gold coast, Australia. cushion subjected to vertical load. Computers and TALL BUILDINGS from Engineering to Geotechnics 30 (2003) 443–453 Sustainability: 6th International Conference on Tall [14] F. Liang, J Li and L. Chen .Optimization Buildings, Mini Symposium on Sustainable Cities, of Composite Piled Raft Foundation with Mini Symposium on Planning, Designand Socio- Varied Rigidity of Cushion. Proceedings Economic Aspects of Tall Residential Living of Sessions of GeoShanghai 2006 Environment,Hongkong , pp241-249.China 2005. .Foundation Analysis and Design – [24] H. G Poulos,. Piled raft foundations: Innovative methods (GSP 153) 29-34. design and applications, Geotechnique 51(2001), [15] S.S Liew, S.S Gue and Y.C Tan Gue & No. 2, 95- 113 Partners Sdn Bhd, Kuala Lumpur, [25] H.G Poulos Simplified design procedure Malaysia.“Design and Instrumentation Results of A for piled raft foundation .Deep Foundation Reinforcement Concrete Piled Raft Supporting 2002:441-458. 2500 Ton Oil Storage Tank On Very Soft Alluvium [26] H.G Poulos and G.Bunce. Foundation Deposits”, Ninth International Conference on Piling design for the burj dubai – the world’s tallest and Deep Foundations, Nice, 3rd – 5th June, 2002. building. Proceedings of the 6th International [16] D.K Maharaj and S.R Gandhi .Non-linear conference on Case Histories in Geotechnical Finite element analysis of piled- raft engineering, Arlington, VA, 2008 foundations.Proceedings of the Institution of Civil [27] M. Rabiebi.Parametric Study for Piled Engineers Geotechnical Engineering 157, 2004 Raft Foundations ,Electronic journal of Issue GE3 Pages 107–113. Geotechnical Engineering Volume 14 ,Bundle A , [17] D.K. Maharaj. Three 2009. DimensionalNonlinear Finite Element Analysis to [28] M. Rabiebi .Effect of Pile Configuration Study the Effect of Raft and Pile Stiffness on the and Load Type on Piled Raft. Proceedings of Load-Settlement Behaviour of Piled Raft Sessions of Geoshanghai 2010 : Deep Foundations Foundations.Electronic Journal of Geotechnical and Geotechnical Insitu testing Geotechnical Engineering ,Volume 9 , Bundle A ,(2004). special publication no. 205:34- 41 [18] H. Nemoto Yaegashi K, Takeuchi [29] O. Reul .Numerical Study of the Bearing Y,Nishimura N,Matsmoto T and Kitiyodom P. Behavior of Piled Rafts . International Journal of vertical load tests of model piled rafts withdifferent Geomechanics, Vol. 4, No. 2, 2004, pp. 59- 68 pile head connection conditions,Proceedings of the [30] O. Reul and M.F Randolf . Piled rafts in Sixth International Conference on Physical overconsolidated clay: comparison of in situ Modelling in : Geotechniques, Hongkong 2006 pp measurements and numerical analyses, 853-859 . Geotechnique 53, No. 3, 301–315, (2003). [19] J Novak, L.C. Reese, and S.T.Wang. [31] L.D Sanctis and Alessandro, A Mandolini Analysis of Pile-Raft Foundations with 3D Finite- Bearing Capacity of Piles Rafts on Soft Clay soils. Element Method. Proceedings of the 2005 Journal of Geotechnical and Structures congress and 2005 Forensic Engineering GeoenvironmentalEngineering, Vol. 132, No.12, Symposium,New York. 2006, pp. 1600-1610, [20] E.Y.N Oh , Q.M Bui , C. Surarak, R [32] Y.K Seo, K.S Choi and S.G Jeong .Adamec and A.S. Balasurbamaniam Parametric Proceedings of the 13th International Offshore and Polar Engineering Conference: Design Charts of

ISSN: 0975 – 6744| NOV 10 TO OCT 11 | Volume 1, Issue 2 Page 45 JOURNAL OF INFORMATION, KNOWLEDGE AND RESEARCH IN CIVIL ENGINEERING Piled Raft Foundations on Soft Clay: Honolulu, Geotechnical Engineering in the information Hawaii, USA, May 25–30,2003 Technology Age (2006) 1-6 . [33] JC Small and HG Poulos.Non-linear [38] K.Yamashita,J.Hamada and Y.Soga. Analysis of Piled Raft Foundations. Settlement and Load Sharing of Piled Raft of a 162 Proceedings of Sessions of Geo-Denver: m High Residential Tower. Proceedings of Sessions Contemporary Issues In Deep Foundations of Geoshanghai Deep Foundations and (GSP 158) 2007.pp 1-9 Geotechnical Insitu testing. Geotechnical special [34] R Sonoda, T Matsumoto, P Kitiyodom, H publication no. 205:26-33 Moritaka, and T Ono. Case study of a piled raft [39] K.Yamashita and T. Yamada Settlement foundation constructed using a reverse construction and load sharing of a piled raft with ground method and its post-analysis, Canadian improvement on soft ground, Proceedings of the Geotechnical Journal. 46(2): 142–159 (2009). 17th International Conference on Soil Mechanics [35] YC Tan, SW.Cheah and M R Taha and Geotechnical Engineering 2009: 1236-1239 Methodology for Design of Piled Raft for 5- [40] M.H Zhao, L. Zhang, M.H Yang. Storey Buildings on Very Soft Clay. Proceedings of Settlement calculation for long-short composite Sessions of GeoShanghai 2006 Foundation piled raft foundation. Journal of Central South Analysis and Design – Innovative Application University of Technology, Volume 13 No.6 749- (GSP153) 226-233 754,(2006). [36] Y.C Tan, C.M Chow and C.M Gue [41] J.J Zheng, S.W Abusharar,and X.Z Wang. Gue & Partners Sdn Bhd, Kuala Lumpur, Three- dimensional nonlinear finite element Malaysia . Piled m edium-rise buildings on very soft modeling of composite foundation formed by clay 2004. CFG–lime piles. Computers and Geotechnics 35 [37] L.G Vásquez, S.T Wang, and W.M (2008) 637–643 Isenhower Estimation of the Capacity of Pile-Raft [42] R. Ziaie-Moayed, M. Kamalzare and Foundations by Three- Dimensional Non-Linear M.Safavian .Evaluation of piled raft foundations finite Element Analysis Geo Congress 2006: behavior with different dimensions of piles. Journal of applied sciences 10(13):1320-1325,2010

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