Location
and type of site play important roles in the behavior of a building not only in
an earthquake but also in normal conditions too. Therefore, site for a building
should be carefully chosen. The common problems that needs to be kept in mind
while selecting sites are below:-
· Water
logged area:- Water logged are should
be avoided for building construction. In water logged area, there may be
possibility of flooding, foundation settlement and liquefaction.
· Earth
filled (back filled) area:-
No building foundation should rest on uncompacted filled ground. In a back
filled area, the bearing capacity of foundation sub soil is low and settlement
of foundation may occur. Also, foundation may be exposed due to easy scouring
of the backfilled soil. If a building is to be constructed on a filled ground,
the foundation should be deep enough so as to rest on the firm ground surface
beneath the fill.
· Steep
and unstable slopes:- No building should be
constructed near to steep and unstable slopes. Steep and unstable slope areas
are the potential areas of landslide and rock fall; there are potential danger
of landslides and rock fall due to rain or ground shaking. Simplest indication
of sustained stability of a slope is the upright standing of tree on it. They
would be inclined downwards in the case of unstable slopes.These steep and
unstable slopes should be avoided. However, buildings can be constructed in
such areas after the provision of proper precaution by retaining walls and
green barriers of bamboo grooves is assured. In such case all wall footings
should be set back from the edge of slope.
· Near
River Bank:- River banks should also
be avoided for building construction. River banks are susceptible to frequent
flooding and also susceptible to liquefaction. Buildings should be far enough
from the flooding zone of the river and construction in such areas should be
undertaken only after carrying out necessary protection works.
· Near
to Big Trees:- Buildings should not be
constructed close to any big tree. Roots of the tree may penetrate into the
foundation and damage the whole building. Also, if a building is near to a big
tree, there is always possibility of falling of tree in strong wind and storms.
· Local
Knowledge:- It is a good practice
during the construction of a building to examine the existing local knowledge
and the history of performance of existing buildings. This will assist in
identifying whether there is any potential danger from inherent natural
susceptibilities of the land to the process of sliding, erosion, land
subsidence and liquefaction during the past earthquakes or any other
natural/geological processes likely to threaten the integrity of the building.
The local practice of managing such hazards, if any, should be judged against
the required level of acceptable risk.
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