tiếng anh chuyên ngành cầu đường: In Construction, What is a Foundation?

In Construction, What is a Foundation?
Whenever construction workers begin work on a new building, they must first
assess where and how they will build the foundation. The foundation is a structure,
commonly made of concrete for homes, that transfers the weight of the building onto
the earth below. There are different types of foundation designs and each serves a
different specific purpose, but generally,
every foundation works to transfer the
weight load of a structure to the soil
beneath.
Most small and medium homes are
built upon a shallow foundation. These are
usually comprised of concrete strips that are
laid about a meter beneath the soil, or of a single large concrete slab that is also set
about a meter beneath the soil. When applicable, the foundation will extend beneath
the frost line. When engineers design the foundation of a building, they must keep in
mind how much the soil will settle beneath the foundation, as well as how much
weight will go on top of the foundation. If calculated incorrectly, the foundation may
fail and place the entire structure in peril.
Larger buildings use a deep foundation rather than a shallow foundation. A
deep foundation uses long pylons of steel or concrete to penetrate deep beyond the
weaker surface soils into the deeper and more stable soils or bedrock beneath. The
load from walls above are transferred deep into the earth, thereby providing support
for the intense weight above. Much like the considerations for a shallow foundation,
engineers must consider weight and settlement, as well as scour or, water eroding
soil beneath the structure.
For structures being built in colder climates, engineers must consider frost
heaves as well. Frost heaves occur when moisture in the soil freezes, thereby changing
the density of the foundation's support. A frost heave can cause damage to the
foundation, thereby compromising the structural integrity of the entire building. Drier,
warmer climates are not entirely exempt from such worries, however: certain soils will
expand and contract when moisture is added or taken away, and engineers must

factor in such movement when considering where and how to lay a foundation.