How to select a suitable type of foundation?


There are different types of foundations for building construction and the selection of a particular type depends on soil conditions and loads from the structure. It is advisable to know the suitability of the chosen type of foundation before making any decision on its selection. The selection of a particular type of foundation is often based on a number of factors, such as:

ADEQUATE DEPTH


The foundation depth depends on the following factors:
  • Getting an adequate allowable bearing capacity of subsoil.
  • For clayey soils, depth should be below the zone where shrinkage and swelling due to seasonal weather changes are likely to cause appreciable soil movements.
  • For fine sands and silts, founding depth should be below the frost zone.
  • For bridge piers, the maximum depth of scour should be considered with the foundation located sufficiently below this depth.
  • Depth of foundation shall be at least below the top soil, miscellaneous fill, vegetation i.e approximately 300 mm below NGL.
All foundations should be taken down to a minimum depth of 0.5 m below natural ground level as a matter of sound engineering practice. In filled-up ground it may be necessary to go beyond the depth of fill or take special precautions to avoid settlement issues for the structure. In such cases, it may be necessary to have a shallow foundation i.e. at a higher level, and replace the soil in between the base of foundation and the level of excavation either by:
(a) Lean concrete, 
(b) Well compacted structural fill to required specifications. The width of fill should not be less than the width of foundation. This is necessary for dispersion of load on either side of the foundation.
In sloping grounds, the horizontal distance from the footing edge (shallow side) to ground surface shall not be less than 60 cm for rock sub-base, and 90 cm for soil. In addition, a line drawn at 30 degrees to the base from the outer edge should not intersect the sloping surface of the ground Read more...

Comments

Post a Comment

Popular posts from this blog

Reinforced Cement Concrete

Image
The acronym RCC stands for Reinforced Cement Concrete. An RCC framed structure is essentially a set of slabs, beams, columns and foundations which are interconnected together to form a stable configuration. The transfer of load in such structure takes place from the slabs to the beams, and from the beams to the columns and finally to the foundation which in turn transfers it to the underlying soil.  The floor area of ​​a RCC framed structure is 10 to 12 percent more than that of a load bearing structure because of the load bearing walls that have a relatively large base area compared with footings for a framed structure. Therefore, there is a real economy in case of an RCC framed structure especially where the cost of the land is very high. Most importantly, in case of RCC framed structures, the internal planning of the rooms, bathrooms, W/Cs etc. can be altered by changing the position of the non-loaded partition walls, thus providing greater flexibility in planning and subs
Read more

What is pile foundation?

Image
A concrete pile is basically a long cylinder in reinforced concrete that is buried in the ground to act as a stable support for the structures that will be built on top of a platform supported by one or more of said cylinders. The set is known as foundation piles or deep foundations. Pile foundations are mainly required for tall buildings as the design loads are too large to be supported on spread footings. Sometimes, when soil has low SBC or the soil is clayey, a raft or a pile foundation may be the solution.   Piles can by classified in 3 ways: The way in which the load is transferred on to the soil. Method of Installation. Material of construction.   Classification of Piles based on load transfer   Point Bearing Piles If bedrock or hard strata is present within reasonable depth, piles can be extended to rest on the bedrock or penetrate required depth into the hard strata. In this case, the ultimate bearing capacity of the pile depends entirely on the und
Read more

What exactly infrastructure engineers do?

Image
Civil infrastructure engineers are required to work with various types of client including private individuals, architects, land developers, master planners and housing developers from one off projects to more regular ongoing assistance and support. They are experienced in developments across sectors including residential, housing, commercial and industrial. Civil infrastructure systems involve design, analysis, and management of infrastructure supporting activities including electric power, oil and gas, water and waste water, communications, transportation and collections of buildings for urban and rural communities. These networks deliver essential services, provide shelter, and support social interactions and economic development. In one line,  they are the lifeline of any society.  Civil infrastructure systems builds on and extends traditional civil engineering areas. Rather than focus on individual structural components or structures, it emphasizes on how different s
Read more