Underwater Evaluation and Repair of Bridge Components

D.S.Ramachandra, Product Manager, Concrete Repair Systems, BASF Construction Chemicals India Pvt. Ltd., Navi Mumbai.
With the rapid increase in vehicular traffic, there is a demand for increase in infrastructural facilities. Due to various constraints the process is still at snails pace and hence the demand for maintenance of existing bridges is becoming important. With most of the bridges being constructed across the waterlines there is a need for underwater evaluation and repair of bridge components. With the occurrence of a series of unfortunate incidences, the importance of underwater evaluation and repair of submerged bridge components is taking a centre stage. In USA guidelines for carrying out the evaluation and repair of submerged components was prepared (FHWA–DP–98–1) and being followed since long time. Indian Railways has started this process with their experience of such unfortunate incidents and have codified the same for their internal use. A series of programs for training of personnel in Underwater inspection and repairs were also initiated by them. However, since the subject involves multidisciplinary skills of Diving and Engineering, it is becoming difficult to operate at macro level in India. Also the equipment involved for such operations being imported and expensive is acting as an impediment for progress. With their individual experiences, however most of the bridge engineers across India have understood the importance of underwater evaluation and repairs of the components. The paper discusses various methods of evaluation of bridges and repair methodologies for different defects found.

Introduction

Most of the bridges across the water line have their foundations in the submerged area and hence are critical for evaluation. These may be constructed of concrete, steel, timber or combination of above. Most of these elements being submerged under water, are prone to fail without any indication (visible by eye. The changing conditions of waterline from the time of construction viz., pollution, and sudden floods cause severe defects in the hidden parts of the bridges. All these conditions lead for formulation of strategic methodology for evaluation and repair of submerged bridge elements. The unavailability of technical diving personnel with technical qualifications and expertise calls for an understanding of the subject by bridge engineers. This would help in guiding the available diving personnel to carry out the necessary operation. The equipment required for inspection apart from diving equipment is expensive and require training to operate. The current paper discusses the following points pertaining to this topic:

• Evaluation Methods
• Diving Systems
• Inspection Tools
• Defects in Structures
• Repair Methodologies & Materials
• New Technologies