Supplementing Site Investigation Techniques of Earthworks and Sub Grade Soils with Geophysical Investigation in Road Designs
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Date
2013-10
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Addis Ababa University
Abstract
In the construction of road projects in Ethiopia, one of the main factors for the delay and increase in cost of road construction projects is huge variation of earthwork item and quantities. This caused the concerned authorities problems of budgetary, questioning of design documents, untrustworthiness on consulting offices, etc.
The purpose of this research is to necessitate the use of geophysical investigation in an attempt to reduce the discrepancy of earthwork quantity and project cost between the design and construction phases.
In order to have sufficient data for the study, records of already designed roads that are not yet constructed or under construction are collected from reliable sources (Ethiopian Roads Authority and International and Local consulting offices). Those data are verified or compared at selected sections (particularly deep cut sections) of the project road using geophysical investigation in the field.
Comparison is also made between the experimental results obtained with the help of geophysical investigation and data collected from the already designed roads.
Based on the results found from the data presentation and discussion, it is observed that lack of detailed site investigation using appropriate method caused major cost overrun and delays in several road projects.
Thus, by studying the area of interest with respect to the required subsurface investigation, planning an exploration technique on a sound geotechnical basis using the test pits supplemented by geophysical technique would bring cost effective result with better accuracy.
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Keywords
Sub grade Soils, Geophysical Investigation, Site Investigation, Road Designs