Page 1 of 6
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 05
May 2019
Available online:https://ejbss.org/ P a g e | 854
Constrtuction Challenges For Bridgesin Hilly Area
K.R. BHOOPATHI
DEPARTMENT OF CIVIL ENGINEERING
PRIST (Deemed to be University), THANJAVUR.
ABSTRACT
A Bridge is a structure built to span a valley, road, river, body of water, or any other physical
obstacle. Designs of Bridges will vary depending upon the function of the bridge and nature
of the area where the bridge is to be constructed. The first bridges were made by nature itself
assimple as a log fallen across a stream or stones in the river. The first bridges made by
humans were probably spans of cut wooden logs or planks and eventually stones, using a
simple support and crossbeam arrangement. Some early Indians used trees or bamboo poles
to cross small caverns or wells to get from one place to another. A common form of lashing
sticks, logs, and deciduous branches together involved the use of long reeds or other
harvested fibres woven together to form a connective rope capable of binding and holding
together the materials used in early bridges. Hilly region pose unique problem for bridge
construction. In a restricted hilly areaitself climatic conditions, geological features and
hydrological parameters vary considerably.Keeping in view the bridge site and various
constraints, type of bridge and method ofconstruction are to be selected carefully for safe,
economical and successful completion of bridgeconstruction. India, a country with a total
area of approx. 3.2 million sq. km. has around 23 % ofits area covered with densely forested,
thinly populated hills. Human habitation and Vegetationspreads to altitudes as high as 14000
to 16000 feet above Mean Sea Level.
INTRODUCTION
Hilly region pose unique problem for
bridge construction. In a restricted hilly
area itself climaticconditions, geological
features and hydrological parameters vary
considerably. Keeping in viewthe bridge
site and various constraints, type of bridge
and method of construction are to
beselected carefully for safe, economical
and successful completion of bridge
construction.
Various challenges that come across while
constructing bridges in hilly area are
Page 2 of 6
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 05
May 2019
Available online:https://ejbss.org/ P a g e | 855
1. Construction of bridge across deep
gorges
2. Construction of bridge on rivers with
bouldary beds
3. Construction of bridges in extreme
temperature zones
4. Construction of bridges on sharp turn on
highway
5. Landslide or Debris flow
Deep gorges, rivers with bouldary beds,
extremely low temperature condition, high
winds,landslide etc. in hilly regions require
special attention to complete the activities
of bridgeplanning and construction in a
systematic way and are discussed here in.
MAJOR ECOLOGICAL PROBLEMS
The association between deforestation and
slope instability has been a subject of
considerableresearch. Deforestation brings
about erosion and soil movement is
generally accepted, butopinions differ on
its impact. So far as "Creeping" slopes are
concerned, greater creep velocitiesare
found in slopes covered by trees in the
region of Tamil Nadu (Nilgiri) nov,2007
than inslopes merely covered by grass in
region of rain forests (Between 1849 to
1992).
Nilgiri(1973 to 1995) reported that
deforestation leads to loss of mechanical
strength imparted byrock system.
Reinforcing power of roots is also
demonstrated by the results of in situ block
sheartests, which show that shear strength
increases with increase in root density. At
higher altitudestop green layer is very thin
and takes hundreds of years to come a
large number of trees along theroadsides
are falling down due to road construction.
Improper road construction results in soil
erosion that may lead to uprooting of large
trees and degeneration of lower plants.
This way itleads to serious ecological
imbalances affecting adversely run-off
factors, temperature gradient,surface
radiation etc. Due to loss of vegetation, the
velocity of runoff also increases that
resultsin soil erosion, hence of soil- fertility.
DESIGN OF BRIDGE ON
LANDSLIDES AREAS
Landslide remedial measures are arranged
in four practical groups, namely:
modification ofslope geometry, drainage,
retaining structures and internal slope
reinforcement. The planning and designing
aspects of the landslide remedial measures
in each groupand presents some illustrative
examples. In addition, debris flow
mitigation measures arediscussed in some
Page 3 of 6
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 05
May 2019
Available online:https://ejbss.org/ P a g e | 856
detail. Back analysis of failed slopes is an
effective tool for reliable design of the
remedial measures while advanced
numerical methods are nowadays
frequently used to design safe and cost
effective landslide remedial measures.
Landslide disaster mitigation options
Risk mitigation is the final stage of the risk
management process and provides the
methodologyof controlling the risk. At the
end of the evaluation procedure, it is up to
the client or policymakers to decide
whether to accept the risk or not, or to
decide that more detailed study isrequired.
The landslide risk analyst can provide
background data or normally acceptable
limits asguidance to the decision maker
but should not be making the decision.
Part of the specialist‘sadvice may be to
identify the options and methods for
treating the risk.
Accept the risk - this would usually
require the risk to be considered to be
within theacceptable or tolerable range.
Avoid the risk - this would require
abandonment of the project, seeking an
alternative siteor form of development
such that the revised risk would be
acceptable or tolerable.
Reduce the likelihood - this would
require stabilization measures to control
the initiatingcircumstances, such as
reprofiling the surface geometry,
groundwater drainage, anchors,stabilizing
structures or protective structures etc.
Reduce the consequences - this would
require provision of defensive stabilization
measures, amelioration of the behavior of
the hazard or relocation of the
development toa more favorable location
to achieve an acceptable or tolerable risk.
Monitoring and warning systems - in
some situations monitoring (such as by
regular sitevisits, or by survey), and the
establishment of warning systems may be
used to manage the risk on an interim or
permanent basis. Monitoring and warning
systems may beregarded as another means
of reducing the consequences.
Transfer the risk - by requiring another
authority to accept the risk or to
compensate forthe risk such as by
insurance.
Postpone the decision - if there is
sufficient uncertainty, it may not be
appropriate tomake a maximum decision
on the data available. Further investigation
or monitoringwould risk.
The relative costs and benefits of various
options need to be considered so that the
