中文摘要：

厚冲积黏土层中开挖深基坑多采用桩锚支护结构,由于锚索变形、土体蠕变、锚固体徐变等造成预应力损失,导致基坑锚索轴力无法维持在设计值水平,折减了基坑安全性。针对此种情况,施工现场大都采用超张拉和二次补偿张拉工法,但超张拉值和二次补偿值却很难确定。根据济南西部厚冲积黏土层中深基坑锚索施工情况,将锚固体系的变形分为锁定前变形及锁定后随时间的变形。根据锁定后锚索自由段的变形得出了适用于两种工法的预应力损失值计算方法,为现场施工提供了理论依据。然后通过现场监测结果和Plaxis数值模拟验证了该计算方法的有效性,最后讨论了该方法的适用范围。

英文摘要：

The deep foundation pit constructed in alluvial thick clay layer is almost supported by using anchor-pile supporting structure. Due to the loss of prestress caused by anchor deformation and creep of anchorage body and surrounding soils with time after the anchor being locked, the axial force of anchor cables in the foundation pit is unable to be kept at the design level. So the safety of the foundation pit is reduced. To solve this issue, the super tension and secondary compensation tension methods to increase the anchorage force are generally adopted at the construction site. However, it is difficult to determine the value of anchorage force in the above two methods. A simple method is given to calculate the axial force of the anchor applied in the deep foundation pit located in the area of thick alluvial clay in western Jinan. In this method, the deformation of anchorage system is separated into two parts according to the construction situation of the anchors:one part is before the anchor being locked and the other is after being locked. The second part induces the loss of prestress which can be represented by the deformation of free segment of the anchor cables. It consists of the creeps in the anchorage body and the surrounding soils. The results applicable to two construction methods give theoretical and technical assistance for in-situ construction. Furthermore, field monitoring and Plaxis numerical simulation are used to verify the effectiveness of the proposed method. Finally, the applicability of the proposed method is given.