分离式加筋土桥台现场试验研究

Field Test and Study of Separated Reinforced Soil Abutment

分离式加筋土桥台具有减跨收坡和节约投资的优势,加筋土桥台与承重结构分离,属于非承重式加筋土桥台的一种形式。依托明巢高速公路分离式加筋土桥台试验段进行现场试验,对桥台竣工后基底垂直应力、面板后水平土压力、桥台整体沉降和水平位移,以及筋材应变分布等进行了分析,探讨分离式加筋土桥台的工程性能。试验结果表明:分离式加筋土桥台基底应力沿筋长方向呈折线形增大分布,面板后水平土压力随时间先减小后增大;工后桥台整体沉降最大处位于桥台后部,沉降曲线受顶部引道施工的影响产生突变;桥台最大水平位移发生在桥台顶部位置附近,最大水平位移约为桥台高度的0.12%;工后土工格栅应变增长较小,格栅应变增量变化受后续施工荷载影响,格栅应变增量逐渐减小为负值,主要与格栅的应力松弛有关。监测结果表明,该分离式加筋土桥台工程性能良好,可为类似工程提供参考。

The separated reinforced soil abutment has the advantages in terms of reducing span,retracting slope and saving investment.The reinforced earth abutment is separated from the load-bearing structure and belongs to a form of non load-bearing reinforced soil abutment.Based on the test section of the separated reinforced soil abutment of Mingguang-Chaohu Expressway,the vertical stress on basement,lateral earth pressure along the back of the abutment face,overall settlement and lateral displacement of the abutment and reinforcement strain after the completion of the abutment are analyzed through field tests,the engineering performance of the separated reinforced soil abutment is discussed.The test results show that the vertical stress on basement increases linearly along the length of the reinforcement.The lateral earth pressure along the back of the abutment face decreases first and then increases with time.The maximum overall settlement occurs at the rear of the abutment face,and the settlement curve has a sharp change due to the influence of top subgrade construction.The maximum lateral displacement occurs near the top of the abutment,which is about 0.12%of the abutment height.The strain increase of the geogrids is small after construction and the strain increment of the geogrid is affected by the subsequent construction load.The strain increment of the geogrid decreases continuously and finally becomes negative,which is mainly related to the stress relaxation of the geogrid.The monitoring results show that the separated reinforced soil abutment has good engineering performance,which can provide reference for similar projects.