一种简化的重力锚承载力估值和结构优化方法

重力式锚碇作为地锚式悬索桥锚碇的重要选型，具有适用范围广，对地基承载性能要求不高等特点。当前承载设计主要考虑了大体型结构及其重量作用下的基底摩擦承载，没有考虑基础与地基的共同作用和基坑埋深带来的上覆增重等的承载贡献，造成锚碇承载和抗滑移安全性能评价的误差较大，具有很大的优化发掘空间。本文在对比传统的平底和新型带齿坎重力式锚碇承载性能组成差异的基础上，探讨了重力式锚碇承载力的组成和每部分的估值方法，提出并建立了综合考虑上述3部分承载效应的重力式锚碇承载力估值公式，同时给出了公式的使用条件和参数确定方法。所得主要结论如下：（1）重力式锚碇的承载性能由基底摩擦效应、齿坎夹持效应和回填增重效应组成。（2）改进的公式与传统公式相比，承载力估值大幅提高，基于此的锚碇结构优化空间巨大。以香丽虎跳峡丽江重力式锚碇工程为例，锚碇最小体积为原体积的2.7%~75.6%，传统公式抗滑安全系数2.42，改进公式抗滑安全系数3.69，安全性能提升空间较大。

A SIMPLIFIED BEARING CAPACITY ESTIMATION FORMULA AND STRUCTURE OPTIMAL METHOD OF GRAVITY-TYPE ANCHOR BLOCK

The gravity-type anchor block, one of the main important anchorage types of suspension bridge, has advantages of wide range of application and low demand for the bearing capacity of foundations. In the calculation of bearing capacity of gravity-type anchor block, the gravity and frictional resistance are taken into account while the resistances generated by the interaction of substruction and foundation as well as the gravity of backfill soil are neglected. It cannot be denied that the omission causes great error on the estimation of bearing capacity and the anti-sliding coefficient of gravity-type anchor block. Through analyzing the difference of the bearing behavior between the conventional anchor blocks and the rugged ones, the estimation method of the bearing capacity of gravity-type anchor block was studied in this paper. And the bearing capacity estimation formula and the using condition as well as the parameter estimation method are provided as well. Conclusions are draw as follows. Firstly, the bearing capacity generated from the base friction, the rugged surface pressure and the gravity of backfill soil. Secondly, comparing with the conventional estimation method, capacity obtained from the modified formula is improved tremendously. This phenomenon tells us that the gravity-anchorage can be optimized immensely. Taking the project of Xiang-Li Tiger Leaping Gorge, the volume of anchorage can be decreased 2.7%~75.6%. And the anti-sliding coefficient calculated from the conventional method is 2.42,while the modified one is 3.69.