某变电站两根钢筋混凝土电杆突然断裂倒塌，造成变压器及相关设备损坏。采用宏观检查、卵石粒径和螺旋筋尺寸测量、预应力筋质量测量、力学性能测试、化学成分分析等方法，对钢筋混凝土电杆的断裂原因进行了分析。结果表明：预应力筋的抗拉强度、屈服强度、质量和化学成分不合格等严重的质量问题，以及电杆在施工安装过程中埋深不足，是导致电杆断裂失效的主要原因。

Two reinforced concrete poles in one substation fractured and collapsed suddenly, causing damage to the transformer and related equipments. Fracture reasons of reinforced concrete poles were analyzed by macro observation, measurement of cobblestone diameter and dimension of spiral steel bars, weigh measurement, mechanical property testing, chemical composition analysis of prestressing tendons and so on. The results show that:the serious quality problems such as disqualification of tensile strength, yield strength, weight and chemical compositions of prestressing tendons, and insufficient installation depth of the poles in the construction process gave rise to the fracture failure of the poles.