现有光纤传感技术或仅能够探测到裂缝的存在与否、或必须事先知道裂缝的准确位置、或必须事先知道裂缝的开展方向等，不能实现裂缝的分布式探测与监测，且采用的单模石英光纤纤细脆弱，不仅在裂缝扩展中容易折断，而且在水利、土木的恶劣、粗放型施工环境中难以存活。针对上述问题，本课题拟采用韧性好、存活率高的多模塑料光纤（POF）替代石英光纤。采用理论分析、物理模型实验和数值模拟相结合的方法，研究裂缝的POF光纤传感模式及裂缝引致的POF光损耗理论，探索基于POF-OTDR技术的裂缝探测与监测方法，提出基于POF-OTDR的光纤新布型，构建分布式裂缝传感网络，实现对混凝土坝裂缝定位、定向和定宽的分布式探测与监测。

The present optical fiber crack sensing techniques can only detect the presence of cracks, or crack locations and crack orientations have to be known a-priori. Silica optical fibers are used in these techniques. They are small in diameter and brittle and easy to break, so they are difficult to survive under the harsh construction environment of water conservancy and civil projects. To solve these problems, polymer optical fibers (POF) with good flexibility and high survivability rate are proposed to replace silica optical fibers. In this investigation theoretical analysis, physical experiments and numerical simulation will be used. The POF crack sensing patterns and the crack induced optical power loss theory will be studied. The POF-OTDR based crack detection and monitoring method will be explored. A POF-OTDR based fiber configuration will be proposed and the distributed crack sensing network will be constructed to realize the distributed crack detection and monitoring with knowledge of crack locations, orientations and widths.