Raft foundations

In special circumstances such as footing for tank on soft alluvial ground, or deep basement with heavy loads over karstic limestone formation, raft and pile raft foundations, and barrette piles are used. To overcome the potential danger from slump zone at the contact between the pile toe and the limestone, compaction grouting is often carried out to infill the slump zone. 

Earth dams are usually constructed on clay soils as they have insufficient load-bearing properties required to support concrete dams. Beneath valley floors, clays may be contorted, fractured and softened due to valley bulging so that the load of an earth dam may have to spread over wider areas than is the case with shales and mudstones. Settlement beneath an embankment dam constructed on soft clay soils can present problems and may lead to the development of excess pore water pressures in the foundation soils (Olson, 1998). Rigid ancillary structures necessitate spread footings or raft foundations. Deep cuts involve problems of rebound if the weight of removed material exceeds that of the structure. Slope stability problems also arise, with rotational slides being a hazard. 

Katzenbach, R. Arslan, U. Moorman, C. 2000. Piled Raft Foundation Projects in Germany. Ch. 13 of Design Applications of Raft Foundations. J.A. Hemsley, Thomas Telford(Ed), London, UK. 

Horizontal cylindrical tanks should be installed on brick or reinforced concrete cradles with a downward slope of 1 in 50 from the draw-off end towards the drain valve, as shown in Figure 18.1. Cradles should be constructed on foundations adequate for the load being supported and the type of soil. A reinforced concrete raft equal to the plan area of the tank, and of adequate thickness to bear the load, is normally suitable for all but the weakest soils. Cradles should not be placed under joints or seams of the tank plates and a layer of bituminized felt should be interposed between the cradle and tank. The height of the tank supports should provide at least 450 mm space between the drain valve and ground level to allow access for painting or draining the tank. 

Until the middle of the 19th century, when William Perkin (1856) discovered serendipitously mauveine, the first synthetic dyestuff, all dyestuffs had been obtained from natural sources. Perkin s discovery sparked a major revolution in the dyeing industry and, over the ensuing few decades, a whole raft of new chromophores were discovered, laying the foundation for the first major industry based on the manufacture of complicated organic chemicals, the European dyestuff industry. ... 

Stability Control of Rafted Pile Foundation Against Soil Liquefaction... 

While a full scale experiment to investigate the seismic behavior of a real structure together with SSPW is hard to conduct, an analytical study with a well verified computational RC and soil model (Maekawa et al. 2003) can serve as an alternative to capture the overall efficiency of SSPW. In this study, the authors use a full three dimensional nonlinear finite element analysis of soil-structure-pore water systems. The applicability of the system was verified by shaking table experiments of top-heavy piles embedded in a liquefiable model foundation (Maki et al. 2004, 2005, Mohammed and Maekawa 2012 Mohammed et al. 2012a). Using this analytical platform, the effects of SSPW as a seismic countermeasure for the rafted pile foundation is discussed with regard to the base shear induced in the RC multistorey superstructure and its overall stability. Both cases of drained and undrained soils are considered in the analysis to clarify the potential effect of soil liquefaction. 

For the purposes of the analytical investigation, a seven-storey building supported by nine columns on a soft sandy soil foundation is considered. The building is 12 m wide and 24.5 m tall and is supported on nine square columns (0.7 m x 0.7 m). A RC rafted pile foundation is considered for supporting these columns on 16.5 m thick of soft sandy soil to bear on a very dense base soil. 

For existing multi-storey buildings supported through rafted pile foundations on a liquefiable soil, the steel sheet pile wall bearing on the non-liquefiable soil surface seems to be an optimum solution for protecting the building from soil liquefaction. 

Senior Management Systems. The fifth level supporting the Release process are the foundation stones, the senior management systems (see the third principle above). These are the systems for managing Recalls, Quality Performance Review, Quality Improvement (including CAPA), Risk, Process Qptimisation, Personnel and QP Development (or QP equivalent in non-production functions). Quality Policies are the final base layer (a concrete raft) and are also part of the Senior Management Systems. In this QMS they are statements of what is done for each of the 25 elements. The process based procedures for each of the individual elements define how the element operates. 

A foundation problem, to explore the effect of changing foundation type and stiffness on total and differential settlements and bending moments in the substructure of a 6-story reinforced concrete office building supported by ds, strips or a raft. 

Commonly used types of shallow foundations include individual footings, strip or continuous footings, combined footings, and mat or raft. Shallow foundations or spread footings derive their vertical loadsupporting capacity entirely from their base bearing resistance, whereas deep foundations derive their axial load-supporting capacity from both side and base resistances. 

Reinforced concrete ground bearing foundation raft with limited service penetrations that are cast into slab 1.5 ... 

The term shallow foundation covers systems of isolated footings (pads) and tie-beams, foundation-beams, and rafts. The same types of foundations are often called spread foundations. Deep foundations, through piles, are not commonly used in buildings and are not treated here. 

Unlike two-way foundation beams, a foundation raft does not offer additional advantages for seismic design. Moreover, its analysis and design... 

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