以三峡水电站坝后背管为例，借助有限元软件ANSYS建立了坝后背管设置软垫层与内衬钢管面摩擦接触有限元模型，考虑接触非线性和混凝土开裂非线性，分析计算了设软垫层坝后背管、钢筋的受力性态及混凝土的开裂情况，结果表明：垫层能有效减小钢管向外围混凝土传递的内水压力，提高钢管的承载比，改善外围混凝土的应力状态。对设置软垫层的提出了优化建议。

In connection with Three Gorges Project, the model of contact between soft layer and inner lining steel tube surface is built by ANSYS, Based on the contact nonlinear and nonlinear cracking, by the non-linear finite element method, the state of stress of steel bar and cracking of concrete are analyzed. The result of calculating indicates:placing soft layer between penstock and concrete can reduce tension stress and improve the anti cracking safety of surrounding concrete, and thoroughly play penstock into full play. The opinions for optimization were put forward finally.