锚拉式支挡结构的变形与内力实测分析研究

以济南某深基坑锚拉式支挡结构的监测数据为依据,分析探讨了锚索拉力、桩身位移、桩身内力的相互关系。总结出影响基坑位移和周围建筑物沉降的因素,得出一些有益于指导基坑设计和施工的结论:(1)通过对基坑锚索拉力的监测数据分析,得出张拉锚索时,若措施不当会造成预应力损失较大;(2)通过设置测斜管和钢筋应力计对桩身位移和内力的监测分析,得出开挖至坑底时支护桩位移及内力出现反弯点,冠梁与锚索的共同效应能控制支护桩的位移与内力;(3)通过对周围建筑物沉降观测分析,得出距基坑远近及水位下降是影响周边建筑物沉降的重要因素,当土质条件较好时,降水产生的建筑物沉降基本可以忽略。

In-situ measurement study on deformation and internal force of pile-anchor retaining excavation

Based on the monitoring data of pulling and arching supporting structure of deep foundation pit in Jinan, the correlations of cable stress, displacement and internal force of the pile were studied. The factors that influence the displacement of excavations and the settlement of surrounding buildings were discussed.Some useful conclusions were drawn, which could help the pit design and construction. First,the monitoring data of foundation pit anchor cable tension analysis showed that the loss of prestress was bigger with the improper measures when the cable was stretched. Second, by setting the inclinometer pipe and steel bar stress gauge monitoring of pile displacement and internal force analysis, the point of inflection of displacement and internal force of pile appeared when the pit was bottomed, and the displacement and internal force of pile could be effectively controlled by combined action of top beam and anchor cable. Third, based on the observation and analysis of settlement of surrounding buildings, it was found that the distance to pit edge and dewatering were the key factors of surrounding building settlement. The settlement of building surroundings pit could be ignored with better soil conditions.