Upload
kidane-mariam-ashenafi
View
230
Download
0
Embed Size (px)
Citation preview
7/28/2019 Presentation Geo Bridge
1/14
GEOLOGICALCONSIDERATION
IN BRIDGE FOUNDATION
&CONSTRUCTION
By Ashenafi Kiros
7/28/2019 Presentation Geo Bridge
2/14
CONTENT:
Definition.
Geological considerations.
Geological characters- -Depth to bed rock .
-Nature of bed rock .
Structural disposition.
Data required.
Factors affecting bridge sites.
Advantages.
Conclusion .
7/28/2019 Presentation Geo Bridge
3/14
Definition:
A structure built over a river,
a dry valley, low or anydepressed part of the landto provide a link between
two opposite sides.
7/28/2019 Presentation Geo Bridge
4/14
7/28/2019 Presentation Geo Bridge
5/14
Geological considerations
:Most rocks of igneous origin are
suitable for bridge foundation.
Amongst sedimentary rocks,
compact beds of sandstone,
conglomerate and breccia aresuitable for taking the load of the
bridge structure and traffic.
7/28/2019 Presentation Geo Bridge
6/14
Geological Characters:
In any major bridge construction
project, the designer is keen to placethe Bridge Abutments and piers on assound strong and stable rock
foundation below as possible. -Depthto bed rock . -Nature of bed rock . -Structural disposition.
7/28/2019 Presentation Geo Bridge
7/14
Depth to bed rock .:
Depth to bed rock . Unconsolidated natural
deposits of sand gravels and boulders.
Such loose materials are not safe forfoundation. Reasons
1.piers placed directly on them would be
unstable.2. the cover material is liable to be removed
due scouring by river water.
7/28/2019 Presentation Geo Bridge
8/14
Nature of bed rock:
Nature of bed rock should be
strong. Most igneous, massive
sedimentary and metamorphic
rocks are quite strong, stable and
durable.
7/28/2019 Presentation Geo Bridge
9/14
Structural Disposition:
Structural Disposition
Horizontal altitude anduniform massive structure
offer inherent resistantagainst failure.
7/28/2019 Presentation Geo Bridge
10/14
Data Required :
Data Required The preliminary Foundation
Geology Report, including test hole locations,
geological description of soils and rock, SPTdata, ground water table locations, temperature
data, permafrost depth, and other data as
applicable. The description of bedrock properties
when present, including planes of weakness,joints, faults, rock type, Rock Quality Designation
(RQD), etc. as they relate to the foundation
recommendations.
7/28/2019 Presentation Geo Bridge
11/14
ac ors a ec ng r gesites:
Factors affecting bridge sites If the bridge lies across
a river joining two mountains, the depth at which
each bridge pier meets the hard sound rock may
vary from pier to pier. This depth can only be gauged
from geological studies.
7/28/2019 Presentation Geo Bridge
12/14
ADVANTAGES :
The subsurface soil description, including unit
weight, relative density, moisture content, phi angle,
and lateral stiffness parameters and modeling
recommendations for each layer of soil. The
presence of permafrost, high ground water table,
and soil stability considerations. The role in socio-
economic development and defence strategies.
7/28/2019 Presentation Geo Bridge
13/14
Conclusion :
From all the point of view
geology in bridge constructionhave more importance. As it is
the necessary part of theconstruction.
7/28/2019 Presentation Geo Bridge
14/14
Thank you.