某高速公路锚索桩板墙原型测试与分析

Field tests and analysis of sheet-pile walls with pre-stressed anchors

对设有两排锚索的桩板墙进行现场原型试验,测试了桩身钢筋应力、变形及锚索拉力。将锚索张拉工况记为BI,BII,并以BI,BII为分界点将填方过程划分为3个工况:AI,AII,AIII。测试数据显示:①在AI工况,桩处于悬臂状态,在填土土压力作用下桩身产生了所有工况中的最大弯矩和大部分桩顶位移,可见工况的设置对桩的受力影响较大,最不利工况可能出现在AI工况或其他中间工况;②BI工况下排锚索张拉完成时桩的弯矩和变形减小的幅度不大,锚索拉力对减小填土已产生的弯矩和变形作用不明显,为使桩受力更合理应尽早对锚索张拉;③AII工况填土引起锁口以上桩身弯矩的增速和AI工况相比明显减小,BII工况在下排锚索处弯矩减小幅度最大;④AIII工况填土主要引起上排锚索位置附近的弯矩变化。结果表明:桩的内力及变形受施工工况影响较大,进行锚索桩板墙设计时,应对工况进行优化并检算;为保证施工期间结构的安全,应对施工工序应进行明确规定。

Field tests on the sheet-pile walls in a highway were performed and the stress of steel bar, lateral deformation of test piles and pulling force of pre-stressed anchor cables were observed. The process of anchor-stretching were reckoned as two conditions signed as BI, BII, while the process of filling was divided into three conditions signed as AI, AⅡ, AⅢ. It was shown that： ① At the end of condition AI, the maximum moment appeared and the most part of displacement at the top of the test piles appeared during construction. So the time of transition from the filling to the anchor-stretching had great influence on the inner force of the piles. The most dangerous state maybe appeared under the condition AI. ② Under the condition BI, the moment value was reduced slightly and the deformation of the piles was restored partly. After anchored, the reduction of the bending moment＇ and the displacement of the top of the piles were unremarkable, so the cables should be loaded as early as possible to make the inner force of the piles more reasonable. ③ The growing rate of the moment in the test piles above the ground descended sharply under the condition AⅡ by contrast with that under the condition AI and the moment of the test piles increased more remarkably near the anchor cables than the moment of other part, furthermore, the most remarkable variation of moment of the piles was found at section of the lower anchor under the condition BⅡ. ④ The variation of the moment of the test piles mainly occurred near the upper anchor under the condition AⅢ. It was indicated that there was a great effect of the construction steps on the inner force and lateral deformation of piles, so the construction conditions should be optimized and the checking calculation should be done when the piles were designed. In order to ensure the safety of the walls during construction, the construction procedure should be clearly regulated.