原文传递
DISASTROUS COLLAPSE OF NEWLY CONSTRUCTED RIVER BRIDGES DURING MASSIVE FLOODS RELEASED FROM RESERVOIR DAMS FOLLOWED BY HEAVY RAINFALL: SAFETY MEASURES SUGGESTED TO AVOID RECURRENCE OF SUCH EVENTS IN PROSPECTIVE ZONES
| 题名： | DISASTROUS COLLAPSE OF NEWLY CONSTRUCTED RIVER BRIDGES DURING MASSIVE FLOODS RELEASED FROM RESERVOIR DAMS FOLLOWED BY HEAVY RAINFALL: SAFETY MEASURES SUGGESTED TO AVOID RECURRENCE OF SUCH EVENTS IN PROSPECTIVE ZONES |
| 正文语种： | eng |
| 作者： | A. G. Namjoshi |
| 摘要： | There is a popular legend (convention) that construction of the water storage reservoir projects/dams across rivers will automatically ensure effective flood control on downstream side of river course. But it is experienced otherwise. During rainstorm/cloud burst in Dam catchments irregular and excessive sudden discharge is released from dams. This causes heavy damages to agriculture land & habitation/property along the riverbanks by submergence for longer periods. This also contributes to sudden rise in flood levels at the works/bridges constructed on the downstream side. It is observed that the flood rises at much higher levels over those observed before the dam construction. The bridges with approaches either get completely washed away or are heavily damaged. The bridges are not designed for such higher flood levels is the common defence put forth for such failures. A few cases of bridges damaged in August 2020 monsoon & some of those occurred in the past three decades are reported in this paper. It is a fact that due to irregular monsoon in central India, reservoirs do not get filled up to full capacity [at 75% dependability i.e. on an average three times in four years] for which they are built. The priority before the dam authorities, therefore, is always to fill the dam [as they cannot afford an empty dam condition when monsoon ends] than to take advance measures to ensure effective flood control. This practice leads to the fact that in spite of advance forewarnings of 'extremely heavy rains' issued by India Meteorological Department (IMD), the dam operators fail to observe the 'Rule Curve' (an internationally-accepted way of reservoir management). Dam operators maintain that any dam can be the most effective flood control measure, provided it is constructed only for flood regulation. Almost all dams in central India are multi-purpose dams, with one or more functions primarily irrigation and power generation/drinking water supply being most common. It will be evident from the above that such events are bound to recur in future also. Therefore it will be advisable to take necessary advance counter measures while designing the new bridges in future. The additional measures required to be taken in the hydraulic & structural design of bridges are suggested in this paper. One case of a major submersible bridge which survived even under the same extreme conditions is studied and some practical measures taken therein are also highlighted, which if adopted will ensure to reduce similar consequent damages in future. |
| 出版年： | 2023 |
| 期刊名称： | Indian Highways |
| 卷： | 51 |
| 期： | 11 |
| 页码： | 19-39 |
检索历史
应用推荐
