Dam heightening ― Barvi Dam in Maharashtra State (India)

摘要

Barvi dam is a fully masonry dam, located at latitude 19°-11′-22″ and longitude 73°-20′-10″ in Maharashtra state. The dam is constructed across river Barvi and has a catchment area of 166.02 Sq.Kms. The dam is constructed for water supply to semi-urban area and industries of Mumbai. The dam is owned by Maharashtra Industrial Development Corporation (M.I.D.C.) of Govt. of Maharashtra. Construction of stage-Ⅰ and stage-Ⅱ of the dam was completed in the year 1976. In stage-Ⅰ the dam of gross storage 121 MCM and height 39m with 122m long ungated spillway was constructed. The storage was subsequently increased to 178 MCM in stage-Ⅱ by installing eleven numbers of automatic gates of size 10 X 4m over the ungated spillway. The full reservoir level and dam top level for stage-Ⅱ was at elevation of 66.05 m and 68.6m respectively. Due to higher demand of water for industrial area, M.I.D.C. proposed to raise the height of dam from elevation 68.60m to 76.22m and F.R.L. from 66.05 to 72.60m. This raising is expected to increase the storage of water by 162 MCM. This is the stage-Ⅲ of the dam. In stage-Ⅲ height of dam was proposed to be raised by 7.62 m. Automatic gates already installed in stagc-Ⅱ are to be dismantled and re-erected on the raised crest. The construction of stage-Ⅲ of the dam is now in progress. The existing dam section was found inadequate for storing additional quantity of water. The dam section therefore required strengthening. Thus strengthening and heightening of dam became necessary. Since raising of the dam is involved the method of full backing on downstream side of existing dam by colgrout masonry section was adopted. This paper discusses the following aspects: 1. Necessity of heightening and strengthening of existing dam section. 2. Design of heightened/strengthened section. 3. Construction methodology. 4. Energy dissipation arrangement downstream of dam.