International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2277-3878, Volume-8 Issue-2, July 2019 2051 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number: B2262078219/19©BEIESP DOI: 10.35940/ijrte.B2262.078219 Abstract: Bridge piers having a varying foundation diameter are known as compound bridge piers. In India for the construction of road and railway bridges circular compound bridge piers are mostly adopted. In past studies it has been concluded that 60-70% of bridge failure occurs because of scour around bridge pier across a river due to flowing water. Most of the past studies were done on the uniform bridge pier and a very few studies has been carried out so far on scour around compound bridge piers. For economical design of bridge pier foundation there is a need to determine the scour depth. In the present study, an experimental investigation has been carried out for computation of time variant change of scour depth for two different models of circular compound bridge piers over non-uniform soil for all possible cases of position of footing with respect to level of the bed, i.e., I. Footing at the level of bed, and II. Footing below the level of bed (1cm, 2cm, 3cm and 4cm) for non-uniform sediments KEYWORDS: Compound Bridge Pier, Scour Depth, Temporal Variation, Non-Uniform Sediment. I. INTRODUCTION Hydraulic structures such as Spurs, Bridge pairs, abutments, guide banks etc. sometime partially abstracts the alluvial streams as a result the bed level Around The structures is lowered because of the interaction between the high velocity flow and the loose bed. This is also caused because of the modification in the flow pattern and drop in the bed level, this phenomenon is known as local scour. The excessive local scour during floods causes failure of bridges and thus it is one of the challenging problems to the hydraulic engineers. In India, hydraulic factors such as stream instability, long-term streambed aggradations or degradation, general scour, local scour, and lateral resettlement are blamed for highway bridge failures. Figure 1.1 shows local scour around bridge piers and foundations, because of flood flows, is considered the primary cause of bridge failure. Phenomena of scour at bridge location is a complex one which is caused by various agents such as localized scour combined with the general river bed degradation, modification of flow field around Bridge structures, human interference, debris flow, etc. Due to the three dimensional flow and sediment transport the complex nature of scour process is observed around bridge elements like piers and abutments. Revised Manuscript Received on July 06, 2019. Abhishek Pandey, Dept. of Civil Engineering, Student of Bharati Vidyapeeth Deemed to be University College of Engineering, Pune, India. P.T. Nimbalkar, Professor, Dept. of Civil Engineering, Faculty of Bharati Vidyapeeth Deemed to be University College of Engineering, Pune, India. Figure 1. Local scour effects in boulder beds, Himachal Pradesh, India With the aim of developing relationships for maximum depth of scour large number of studies has been carried out on this topic and thus on the subject of scour around the bridge pier a huge amount of literature is available. However only a few studies are conducted on the flow field around the bridge elements. Through the Laboratory experiments the flow pattern within the scour hole around circular uniform Bridge has been studied by [1] these studies have mostly focus on scar around Bridge pairs which have uniform cross section along their Heights. It also Consider the effect of foundation geometry on scour which previous researches did not considered. In practice Bridge pairs are constructed in various types of symmetries have non-uniform cross-section along their Heights. The investigators [1-3] have shown that foundation geometry significantly affects the scour. All the above studies are carried out with uniform sediments. The various factors affecting scour such as type of flow, depth of flow, effect of shape of pier, angle of inclination of pier with flow, opening ratio and bed material characteristics are studied in detail. Standard provisions in the country with reference to bridge pier scour are reviewed. The various relationships proposed by researchers to estimate bridge pier scour in clear water condition and live bed condition are reviewed. Temporal variation of scour around bridge pier is studied and the procedure to estimate the same is reviewed. Based on review of literature it is found that there is a need to carry out further research with respect to compound piers to study the aspect related to placing of top of footing and its effect on bridge pier scour in non-uniform sediments so only the effect of pier foundation diameter ratio on scour is studied in this report. Thus the research problem along with objectives and scope of study is finalized. The present study describes the details of experimental investigations carried out in the laboratory on compound bridge pier for five different Effect of Soil Non-Uniformity on Scour For Circular Compound Bridge Piers Abhishek Pandey, P.T. Nimbalkar