DESIGN OF GUIDE BUNDS & HYDRAULIC SIMULATION OF FLOW AROUND MAJOR RIVER-ROAD BRIDGES

Abstract

Bridges over the major rivers are very important and expensive highway hydraulic structures. These Bridges are vulnerable to failure from flood. In order to minimize the risk of failure, the hydraulic requirements during the development, construction, and maintenance highway phases must be recognized and addressed. Some of the important hydraulic analyses of a highway-stream crossing for a particular flood frequency are :- i) Determination of the effects on flow distribution and velocities due to bridge, ii) The Profile of Guide Bunds and its proper protection measures. Guide Bunds are earthen embankments with stone pitching in the slopes facing water, to guide the river through the bridge. These river training works are provided for rivers flowing in planes, upstream and downstream of the hydraulic structures or bridges built on the river. Marginal Bunds is flood embankments in continuation of guide Bunds designed to contain the floods within the flood plain of the river. They are provided on the upstream in order to protect the area from submergence due to rise in HFL, caused by afflux. Generally, Guide Bunds in the upstream of bridges are constructed as per conventional guide lines with help of model studies. During the construction of long guide Bunds, beside the cost of construction, very large lands are to be procured. This procurement of land sometimes leads to very long and tedious litigations and huge amount of compensation to the farmers, public owners. To avoid these litigations and to reduce the heavy revenue cost sometimes, deviations from common guide lines are strategically required. At certain locations, it may be possible to obtain a firm and stable topography on one or the other side. In such cases only one Guide Bund on the other side needs to be provided. Obviously the cost of river training is reduced in such cases. No standing guide line can be framed for such strategic positions which are to be solved at hand. With this philosophy, in the present study the existing marginal Bunds is being used as left guide Bund. This marginal bund is suitably tied up with S-Curve with the existing dyke Bund and marginal Bund. Elliptical guide Bund with reduced length is provided on the right side for the Bridge 1. Similarly Elliptical guide Bunds with reduced length are provided on both sides for the Bridge 2 without interfering the hydraulics of the bridge. The Bridge 1 is located near Baghpat & Bridge 2 is located near Faizupur Khadar along the Eastern Peripheral Expressway in the river Yamuna. It is with this objective, so as to review the proposed alignment iii of the Guide Bunds and protection work of Yamuna River Bridge. Also to suggest alternate technical measures on the basis of the previous study carried out the Irrigation and Power Research Institute, Punjab; Amritsar. As the time does not permit the new physical model study or the collection of primary data, secondary data only is being used for the analysis. Similarly the proposed Bridge 3 in the river Ganga near Hastinapur was designed for a flood of 11,250 cumecs based on 3D Physical model studies conducted by Irrigation Research Institute, Roorkee in 2009. But in the year 2013, the flood of 14668 cumec was experienced at a barrage constructed about 32 Km upstream of the bridge. So seeing the importance of the bridge in consideration and under construction the hydraulics analysis of the flow with discharge of 14,500 cumecs is carried out for extra line of defense for the main structure under present scenario. As the time does not permit the new physical model study or the collection of primary data, secondary data only is being used for the analysis through mathematical model.