坝后式水电站压力钢管厂坝过缝措施研究

Study on Measures for Passing Joint between Dam and Powerhouse of Penstocks on Downstream Surface of Dam

本文结合某水电站的工程实例，采用三维有限元法，对厂坝分缝处的伸缩管段预留环缝的焊接时间、厂坝分缝处键槽的合拢时机以及键槽合拢的效果对于伸缩管的影响进行了敏感性分析。计算结果表明，如果在蓄水前对厂坝分缝进行灌浆处理，则推迟钢管环缝焊接时间，可以减小钢管的等效应力，但是降低的数值较小。在蓄水前如未进行厂坝分缝处的灌浆而仅仅焊接钢管的环缝，将大大降低厂坝之间的联合作用，并且恶化伸缩管的应力状态。厂坝分缝处的键槽合拢效果对于伸缩管将会产生一定程度的影响，若键槽合拢后存在缝隙将会造成分缝处钢管局部应力增大，而灌浆材料的选取对于钢管影响不大。

In combination with the practice of a hydropower station, the sensitivity analysis on many factors affecting deformation and stress of penstock with cushion layer outside, which include the welding time of penstock, the closure time of key grooves between powerhouse and dam as well as the closure effect of key grooves, are performed by means of three dimensional finite element method. The results indicate that if the joint grouting is completed before water storage, postponing welding time of circular seam can help reduce the stress of penstock indistinctively. If the penstock is only welded before water storage, combining effect between dam and powerhouse is reduced greatly and stress condition of expansion pipe is worsened. The closure of key grooves has an influence on the expansion pipe to some extent. If the key grooves have not closed up completely, the local stress of penstock increases. Moreover, grouting material does not have a great influence on penstock.