Abstract:

Chambon, a 137 m high concrete gravity dam completed in 1935, is affected by severe alkali-aggregate reaction, causing several types of pathologies as a result of the concrete expansion. They mainly result in important vertical cracking of the structure, likely to affect its integrity under earthquake, important shear stresses in the structure and deformation of the crest. Reinforcement works were performed from 1991 to 1997 to guarantee the safe operation of the dam: mainly a series of slot cutting, and a drained PVC sealing geomembrane system, installed to provide waterproofing protection at the upstream face. These measures allowed an extension of service of 20 years.

New reinforcement works were performed in 2013—2014, in the continuity of those already performed in the 1990's: (1) installation of 415 prestressed tendons crossing the structure from upstream to downstream, supplemented with a carbon fiber composite net on the upstream face, (2) realization of 7 vertical diamond wire slot cuts and (3) replacement of the existing sealing geomembrane to allow the works.

This paper explains the approach that led to the choice of technologies based on the results of investigations and finite elements modeling.

Key words: alkali-aggregate reaction, modeling, tendons, cuttings, membrane

摘要：

Chambon大坝于1935年建成，是一座高137 m的混凝土重力坝。由于受碱骨料反应影响严重，Chambon大坝混凝土膨胀，出现了多种病害缺陷，主要造成了结构的竖向开裂（在地震作用下可能影响结构的完整性）、结构产生剪应力和坝顶变形。为保证大坝安全运行，1991—1997年，对Chambon大坝进行了除险加固，主要包括一系列开槽，并在上游面安装了排水PVC管和土工膜防渗系统，以提供防渗保护。这些措施可将大坝服役期限延长20年。

2013—2014年，对Chambon大坝进行了新一轮的补强加固，其延续了20世纪90年代已进行的补强加固：（1）从上游到下游，贯穿结构布置了415根预应力钢筋束，并在上游面加装碳纤维复合网；（2）采用金刚石线切槽，完成7条垂直槽；（3）更换现有的防渗土工膜。

笔者主要阐述基于调查结果和有限元建模分析所做的技术方案选择。

关键词: 碱骨料反应, 建模模拟, 钢筋, 切割, 土工膜