The main navigational channel bridge of Hutong Changjiang River Bridge is a steel truss girder cable‐stayed bridge with span arrangement of (142+462+1 092+462+142) m .The foundations of the pylon piers adopt caisson foundations ,among w hich the top plan dimension of steel caisson of pier No .28 is 86 .9 m by 58 .7 m ,and 44 m high .The steel caisson for the pier No .28 was fabricated in a dock and then transported to the bridge site by floating ,with a total floating weight of up to 14 500 t .To rationally allocate the floating tugboats and assure smooth floating ,the theoretical method ,numerical simulation method and physical model testing method were used to calculate the floating resistance of the steel caissons .Based on the comparative analy‐sis ,by modifying the head and end shapes of the boats ,the results gained by using the method presented in the Guidelines for Towage At Sea is approximate to those gained respectively by nu‐merical simulation and physical model testing ,w hich is proved applicable to the floating resistance calculation for the steel caisson of pier No .28 .It is proposed by calculation that the steel caissons have a draft of 8 m ,when the wind speed is at Grade 6 ,and the tugboat′s speed through water is 2 . 5 m/s ,the total resistance for a steel caisson is 2 167 kN under the condition of longitudinal to‐wing .The arrangement of the tugboats adopts the“7+1”mode ,namely one used as a backup tug‐boat ,the efficient output towing force is 3 060 kN ,and the maximum resistance of the towing is 2 326 .74 kN ,satisfying the floating requirements of the steel caisson .%沪通长江大桥主航道桥为（142＋462＋1092＋462＋142） m钢桁梁斜拉桥，桥塔墩基础采用沉井基础，其中28号墩钢沉井顶平面尺寸为86．9 m ×58．7 m ，高44 m。28号墩钢沉井在船坞内制造完后整体浮运至桥址处，浮运总重达14500 t。为合理地配置浮运拖轮，确保浮运顺利，采用理论方法、数值模拟方法和物模试验方法对钢沉井浮运阻力进行计算。经过对比分析，经首尾形状修正的《海上拖航指南》方法计算结果与数值模拟和物模试验结果相近似，适用28号墩钢沉井浮运阻力计算。通过计算，在钢沉井吃水8m、风速6级、对水速度2．5m／s时，钢沉井纵向拖航的总阻力为2167kN ；采用“7＋1”8艘（1艘备用）拖轮的配置模式进行拖航作业，有效输出拖力（3060 kN ）＞拖航最大总阻力（2326．74 kN ），满足钢沉井浮运要求。
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