中文摘要：

石长铁路沅水特大桥随使用年限的增长,多孔32 m预应力钢筋混凝土T梁出现不同型态的裂缝。通过施工温度、混凝土强度、力学等方面对裂缝进行成因分析,研究结果表明：沿预应力管道方向纵向裂缝的主要原因是管道的曲率半径减小14%或预应力超张拉超过14%,使预应力管道处混凝土所受的拉应力超过混凝土的标准抗拉强度,导致产生纵向裂缝;梁端竖斜向裂缝是因上、下侧预应力钢束预张力不同,引起支座上端T梁上翼缘底部处弯矩的不平衡,其差值超过混凝土的极限轴心拉应力,导致裂缝产生,为以后的桥梁加固提供重要的技术支持。

英文摘要：

With the increase of smwiee life, Yuanshui bridge in Shichang rmlroacI appemvu ~--- cracks in 32 m prestressed concrete T beams. The crack causes were analyzed from several aspects, such as the construction temperature, the strength of concrete, the mechanical performance. It is found that the main cause of longitudinal cracks along the direction of the prestressed pipe is that when the radius of curvature of pipeline reduced by 14% or the stress prestressed more than 14% , the concrete tensile stress in prestressed pipe exceeds standard tensile strength of the concrete, thereby resulting in the longitudinal cracks; The vertical diagonal cracks in the beam terminal are induced by different pretension on the upper and lower sides. The imbalance of bending moment at the upper bearing top flange bottom of T beam is therefore caused. When the difference ex- ceeds the concrete axial tensile stress, it results in the occurrence of cracks. The findings in this paper provide important technical support for future bridge strengthening.