光纤传感技术在大坝裂缝预测和监测中的可行性探讨

Feasibility Study on Application of Optical Fiber Sensing Technology for Prediction and Monitoring of Dam Cracks

大坝结构内部应变监测和裂缝监测是大坝健康的主要指标。由于各种因素的影响,导致难以判断坝体裂缝产生的具体位置。传统的点式电测仪器很可能漏检,而分布式光纤裂缝传感器能捕捉随机裂缝,分布式光纤应变监测系统能感知大坝各部位应力应变,将这2种系统联合使用,则能达到在裂缝产生前预报裂缝、在裂缝产生后监测裂缝的双重效果。光纤网络的优化布设一直是光纤广泛应用于工程中的难点。施工前分析混凝土坝在不利工况下运行的应力应变,根据分析结果对光纤网络进行立体优化布设,建立大坝健康监测智能系统,实现对大坝的实时、在线、立体监测。通过试验,验证了光纤传感技术在裂缝预测和监测中的有效性。

Dam internal strain and cracks are main indexes of dam structure health. Because of various factors, the crack locations are difficult to be determined. The cracks in a focal area may fail to be detected with a conventional electrical measuring instrument; distributed optical fiber crack sensors can detect random cracks and disti＂ibuted optical fiber stress-strain monitoring system can measure stress and strain of various locations of a dam. These two systems combined, potential cracks can be predicted before their occurrence, and the cracks can be monitored after wards, so double effects can be achieved. The optimized layout of optical fiber network is always a difficulty in the wide application of optical fiber sensor system in actual engineering. Before the construction of a dam, the stress-strain distribution under unfavorable conditions has been analyzed. Based on the analysis result, a three-dimensional optical fiber network can be optimally laid, so that the monitoring system can really become the nervous system of the dam, then the intelligent system of dam health monitoring can be built, and the realtime on-line monitoring can be realized. By experiment the validity of optical fiber technology for predicting and monitoring cracks is verified.