الفهرس 
CHAPTER ( 1 ) : INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
A differential settlement at the end of a bridge near the interface between the abutment and the embankment is a persistent problem for highway agencies. The differential settlement produces the common “bump at the end of the bridge”. Reduction in steering response, distraction to the driver, added risk and expense to maintenance operation, and reduction in a transportation agency’s public image are all undesirable effects of these uneven and irregular transitions. Major causes of the bump include settlement of foundation soil, compression of fill material and erosion of the backfill. Hence, it is important to predict the bump at the end of the bridge from the beginning stage of embankment construction and reasons for the bumps. This research attempts to simulate the bump at the end of the bridge using PLAXIS finite element 2D program. PLAXIS was used to simulate a laboratory model called Bridge to Embankment Simulator of Transition (B.E.S.T.) device which was built by Seo, J. B. (2003) to investigate this problem. A total of six numerical simulations were conducted using hardening-soil model with rational assumptions of missing soil parameters to evaluate the bump at the end of the bridge. The results show good agreements between the numerical and the laboratory models. The agreement of results revealed in both medium sand and clay cases as well as in single and double-span approach slab cases. However, significant divergence of settlements results, increasing with the increase of cyclic loading, appeared in loose sand cases. Important factors influencing bumps at bridge ends were also addressed in light of the model results.
In addition, field investigations were conducted at bridges in Minya Governorate, SAFT AL-LABAN and DAMARIS bridges. The results show good agreements between the numerical model and the measurement of the actual bump at bridge site.
The results for two study sites show the possibility of using PLAXIS to simulate any new bridge, the actual bump is close to the theoretical bump at both sites, the presence of the transition slab reduce the settlement by 14.07 percent at the end of the transition slab with the road, by 31.23percent at the end of the transition slab with the bridge. The compaction of soil during the construction would be a key factor to prevent or minimize the bump. The main reasons for the development of a bump were found to be due to the settlement of the embankment resulting from high average daily traffic, increase the age of the bridge, voids under the pavement due to erosion, and weak natural soil.