Abstract:

A brief description of the principle, detection equipment and technical indexes of neutron method was used to detect the inner cavity defect of concrete under steel palte lining. The specific introduction of site testing conditions and results of 7 runner chambers in Shuikou hydro-power plant were described in this article. The results showed that each runner chamber had several pieces or isolated inner cavity defects, which depth were less than 3 mm. Except 1# runner chamber, all of the rest had isolated inner cavity defects which depth were within from 3 mm to 10 mm. Affected by falling of steel plate, the depth of inner cavity defects in 3# runner chamber were larger than 10 mm. A remeasurement for 3# runner chamber after grouting was carried out, and summarized guidance for the retested results. In addition, the reasonable analysis was did in the aspect of grouting, the water content of the background and cavitation for the high thermal neutron count of 3#, 4# and 6# runner chamber. The successful application of neutron method for detecting inner cavity defect of concrete under steel plate lining of the runner chamber provides a reliable means of detection and scientific basis to the construction and operation safety of permanent components embedded in concrete in water conservancy projects.

Key words: neutron method, cavity detection, concrete under steel plate lining, runner chamber

摘要：

利用中子法探查厚钢衬下混凝土脱空方法原理、检测仪器及技术指标，对福建水口电站7台机组的转轮室现场进行检测，检测结果表明，不同机组转轮室都存在分散性的小片或零星孤立的脱空深度小于3 mm的微小脱空区域，除1#机组转轮室外，都存在局部孤立的脱空深度在3～10 mm脱空点，受钢板脱落影响，仅3#机组转轮室存在脱空大于10 mm的脱空区域，后期对其进行了灌浆处理和复测，并对复测结果给出了指导性意见。另外，针对3#、4#、6#机组转轮室热中子计数明显偏高的现象，分别从灌浆、背景含水量、气蚀等方面对其进行了合理性分析。中子法脱空检测技术在机组转轮室钢衬下混凝土脱空检测中的成功应用，为水利工程钢衬下混凝土永久埋设部件工程建设与运行期安全监督提供了可靠的检测手段与科学依据。

关键词: 中子法, 脱空检测, 钢衬混凝土, 转轮室