牂牁江特大桥重力锚承载机制与稳定性研究

Study on the Bearing Mechanism and Stability of the Gravity Anchorage of Zangkejiang River Super Large Bridge

依托牂牁江特大桥纳雍侧重力锚工程,采用FLAC3D三维数值模拟与理论分析相结合的研究方法,模拟了超载条件下锚碇-地基系统的力学响应,分析了锚碇变位、齿坎夹持岩体剪切承载特征、塑性区演化规律及系统的稳定性,揭示了重力锚结构-地基联合承载机制。结果表明:纳雍侧重力锚的极限承载力为6P;锚碇在缆力荷载作用下发生变位,进而通过基底摩擦及齿坎夹持效应调动周围地基岩体共同承载,且调动岩体承载的顺序为从基底向上逐级调动各级齿坎,齿坎夹持部分的岩体则是通过抗剪作用提供被动抗力;理论分析和数值模拟结果均表明,同时考虑摩擦和齿坎夹持效应时,工程设计缆力荷载作用下锚碇-地基系统的稳定性系数可达6.0以上,远大于仅考虑摩擦效应时的稳定性系数。

Relying on the Nayong bank gravity anchorage project of Zangkejiang River Super Large Bridge,the method of combining three-dimensional numerical simulation of FLAC 3D with theoretical analysis were adopted,the mechanical response of the gravity anchorage-foundation system under overload conditions were simulated,the displacement of the anchorage,the shear bearing characteristics of the rock mass clamped by the tooth sill and the evolution law of the plastic zone,as well as the stability of the system were analyzed,and the combined bearing mechanism of gravity anchor structure and foundation.The results show that the ultimate bearing capacity of Nayong bank gravity type anchorage is 6P.The anchorage is displaced under the action of the cable force load,and then the common bearing of the surrounding foundation rock mass is mobilized through the friction of the base and the clamping effect of the tooth sill.The order of the bearing of the rock mass mobilized is to mobilize each tooth sill step by step from the base,and the rock mass clamped by the tooth sill provides passive resistance through shear resistance.The theoretical analysis and numerical simulation results all show that the stability coefficient of the gravity anchorage-foundation system can reach more than 6.0 when the friction and the clamping effect of the tooth sill are considered simultaneously,which is much larger than the stability coefficient when the friction effect is considered only.