秀山大桥重力锚支墩基础与锚块各自分开,地基与基础荷载分担比较为复杂,为研究锚碇系统各部位承载分担比和失稳模式,依托秀山大桥重力锚,建立锚碇、支墩桩基与地基相互作用的三维有限差分模型,以0.5P(P为缆索拉拔设计荷载,P=132 MN)为递增荷载进行极限加载模拟研究。结果表明:在(1~2)P时,锚块底板、锚块前端岩体、支墩基础、锚块侧边承担水平荷载平均占比为64%,23%,6%,7%;缆索荷载达到2.5P时,锚-岩接触面不均匀剪力引起锚块底部岩体拉伸破坏;支墩桩基达到极限承载力时的缆索荷载为3.5P,其破坏形式近似于单轴压缩破坏;随着荷载继续增大,锚块底板接触面逐渐张开,其承担水平荷载向锚前端岩体转移。研究成果为重力式锚碇的结构设计、地基加固及极限承载力分析提供了参考。

The load sharing ratio of gravity anchor pier foundation of Xiushan bridge is complicated as the foundation is separated from anchor block. In this article, a 3-D finite difference model of the interaction among anchorage, pile foundation of support pier, and ground is established to research the load sharing ratios and failure modes of different parts of the anchorage system of Xiushan bridge. The simulation load increases by 0.5P (P is the design cable load) until limit state appears. Results reveal that when cable load is between 1P and 2P, the load sharing ratio of anchor block bottom, rock mass in front of anchor block, support pier foundation, and anchor block side is 64%, 23%, 6%, 7%, respectively; when cable load reaches 2.5P, tensile failure of rock on the bottom of anchor block appears due to non-uniform shear force on the interface between anchor and rock. The limit cable load of support pier foundation is 3.5P, approximated to uniaxial compressive failure. As load increases continuously, the contact surface of anchor block bottom gradually detaches, and the horizontal load moves toward the rock mass in front
of anchor block. The research achievements offer reference for the structural design, foundation reinforcement, and limit bearing capacity of gravity anchorage system.