软岩地基悬索桥重力式锚碇齿坎效应的试验研究与数值分析

 基于刚体计算模型，首先从理论上探讨座落在软岩地基上的悬索桥齿坎重力式锚碇的齿坎效应工作机制，得出如下结论：锚碇结构重心位置决定齿坎抗滑效应产生的方式和效果。其次，以赣州赣江大桥作为工程为例，通过现场模型试验分析不同应力水平下，锚碇各级齿坎的应力分布情况，进而研究齿坎的抗滑效应，并检验齿坎效应的上述理论成果。最后，利用FLAC3D对重力式锚碇的受力特性进行三维数值模拟，分别就有、无齿坎锚碇与软岩地基的共同作用情况，包括齿坎各接触面抗滑力分布情况进行计算分析，结果表明：齿坎的存在改变基底应力分布，减少锚碇的水平位移，大幅度地提高极限抗滑力，并最终改变锚碇破坏模式。研究表明，现场模型试验结果与数值计算分析结果是一致的。基于上述研究成果，讨论锚碇结构重心、齿坎高度、接触面以及地层参数等因素对锚碇结构齿坎效应的影响，并提出带齿坎的重力式锚碇结构的设计原则。

TEST AND NUMERICAL ANALYSIS OF EFFECT OF NOTCHED SILL OF GRAVITY ANCHORAGE ON SOFT ROCK GROUND OF SUSPENSION BRIDGE

Based on the rigid calculation model,the formation mechanism of notched sill effect of gravity anchorage is analyzed for suspension bridge on soft rock ground. It reveals that the mode and performance of notched sill effect mainly depend on the centroid position of anchorage. Taking the anchorage project,Ganjiang suspension bridge on Ganjiang River for example,field model test for anchorage is conducted to investigate notched sill effect by studying the stress distribution of each step of notched sill subjected to different cable tension levels. The results from test validate the formation mechanism of notched sill effect. Additionally,three-dimensional numerical simulation is performed to disclose the mechanical characteristics of gravity anchorage with notched sill by means of the fast Lagrangian analysis of continua in 3 dimensions(FLAC~(3D)). The interaction between surrounding soft rock and anchorage both with and without notched sill is studied. It is concluded that the existing notched sill obviously influences the stress distribution on the bottom of foundation,decreases the horizontal displacement,greatly improves the anti-sliding capacity,and changes the instability mode of anchorage. The results from numerical simulation are in good agreement with ones from the field test. Moreover,the analyses of factors of notched sill effect,including the centroid position of anchorage,the height of notched sill and the parameters of interface and surrounding ground,are implemented for structural optimization design. Finally,some principles for designing anchorage structure with notched sill are suggested.