中文摘要：

由修正势流理论获得了海管沿轴向升力分布,运用海管的小挠度微分方程,通过有限元计算得到有混凝土配重海管的平衡位移和应力,分析跨肩约束、混凝土刚度和来流速度对最大位移和最大应力的影响,讨论悬跨长度增加时刚度失效和强度失效的行为规律,给出不同跨肩约束条件下随间隙比和来流速度变化的安全跨长分区图。结果表明：悬跨海管首先出现刚度失效,触底后则会发生强度失效;间隙比和跨肩约束是影响安全跨长的重要因素;来流速度小时,必须考虑海管的静态临界安全跨长。

英文摘要：

Applying the lift force distribution along a free spanning pipeline near seabed obtained by the modified potential method,the displacements and stresses of the pipeline with steel-concrete structure were investigated by the pipe dynamics equation.Using the finite element analysis and iterative method,the effects of concrete stiffness,constraints in span shoulders and current velocity on the maximal displacement and stress were analyzed.The stiffness failure and strength failure were discussed when the spanning lengths extend.The safety lengths zone schemes were drawn under different gap ratios and current velocities.The results suggest that the stiffness failure takes place first when the spanning length increases and the strength failure then may occur after the pipeline touching seabed.The gap ratios and constraints at the span shoulders are important factors in the allowable spanning length.The static critical allowable length should be considered firstly when the current velocity is relatively small.