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Engineering Stack Exchange

Questions tagged [foundations]

37 questions
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Why dig out and then fill in before building a large structure?

I work in the middle of London, in an area full of large office blocks. Across the road from my office they have started construction of a large building (10 stories plus). Over the last few weeks, diggers have dug a large (and vertical walled)…
AndrewD
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What is the purpose of building foundations?

According to many sources, one of the purposes of building's foundations is "To distribute the weight of the structure over large area so as to avoid over-loading of the soil beneath." (Wikipedia) On the Wikipedia page on foundations, there is the…
S. Rotos
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Why is this construction site pouring gravel over a wire mesh, and then covering it with dirt?

My office is afforded a prime view of a construction project where the workers are currently covering the leveled ground in a wire mesh, raking gravel across the entire mesh, and then covering that gravel layer in another layer of dirt. What is the…
TylerH
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For train track, why does the ballast need "good drainage"?

Why does the ballast of train track need good drainage? I read something about preventing "fouling" of the ballast, but don't know what that means or why it would be structurally bad. Could foundational support play a role, where soggy ground would…
DrZ214
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What is the down-stand beam called at an edge of a surface bed or raft foundation?

What is the down-stand beam called at an edge of a surface bed or raft foundation? It is not exactly a grade beam or stem wall. It is more like a toe.
SlydeRule
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Foundation Excavation: How much larger than the RCC footing?

I am trying to estimate the volume of excavation needed for the foundations of a structure from the drawings provided. The drawings clearly give the dimensions of the RC / cement footing but I suppose the actual excavation will need to be larger…
curious_cat
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How to model elastic support in FEM?

I need a 8 m x 4 m x 0.6 m RC plinth (mechanical requirement) which needs to be built onto loose gravel. Obviously I am going to over excavate, back fill with selected material and bed my plinth on that. The plinth accommodates 2 x 65 m3 water…
SlydeRule
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What does "crs" mean in structural engineering / construction?

In the realm of structural engineering, construction, foundation design, what is "crs" when talking about piles/posts? Is it an abbreviation? Does it refer to some sort of size? Some examples:
Greendrake
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Stress Bulbs for strip "continuous" footings

How can I plot such a graph with Excel or Matlab by a uniform load q, and how can I see where the stress becomes 0.1q? The loaded area and the equation is on the picture shown below, equation is highlighted in yellow
Murad Nazari
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2 answers

Bored Pile construction Procedures When having Water in the ground

I know the normal process of how bored piles are normally constructed, but I need to know in case we have a water table at 1.5 m under the surface level and the pile must be at a depth of 25 m. How do they prevent the water from filling into the…
J.Daou
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Low pile capacity during pile driving

When driving piles, the resistance from the soil is constantly measured. What happens when the expected resistance values from the soil are not obtained? For a single pile or for multiple piles? What do we do in that case?
upstream
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Concept design for an extension to a blanket raft slab

A blanket raft is a type of solid slab raft consisting of deeper ‘toe’ sections running around the edge of the foundation as well as a central deeper ‘beam-like’ section which offer rigidity to the slab. The blanket raft in question is 250 mm deep…
egg
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Building Uplift due to water pressure

I have a building that is 7 story height (which 5 stories are basement floors which means they are underground) My water level is at 1.5 m from the surface. the stories have typical rectangular shape of 30 m x 36.2 m with a grid of columns as shown…
J.Daou
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Can shear links be designed to hook between inner layers of top and bottom reinforcement?

I am tasked to design a bridge pile cap. Shear links are required. However due to heavy reinforcement used, contractor requested to hook the links between inner rebars to ease construction. Is this allowed in British Standard? How should this be…
joanne
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why are foundations designed at SLS

Why do we design foundations at SLS and not ULS? If we use ULS wouldn't we be taking a higher factor of safety? SLS = Serviceability limit state. It considers how the structure is actually expected to behave, generally by using partial factors of…
Mohammad
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