李家峡拱坝大吨位锚索内锚固段岩体变形分析

Deformation analysis on rock mass around anchorage section of large-tonnage prestressed cable of Lijiaxia arch dam

开展大吨位预应力锚索内锚固段岩体变形研究,对分析其加固作用机理、指导大型岩土结构的加固设计具有重要意义。本文通过分析李家峡拱坝重力墩大吨位锚索内锚固段岩体变形的十多年观测结果,对锚固段的岩体变形特性、锚固段岩体变形与垂线测量值的关系、长期作用下预应力锚索锚固力损失等进行初步研究。分析结果表明:(1)垂线观测资料真实反映了大吨位锚索内锚固段周围岩体的变形;(2)内锚固段一定范围内,周围岩体存在较严重的损伤破坏;(3)尽管锚索的张拉施工是在短期内完成的,但是内锚固段岩体的变形却要在4～5年内缓慢完成,不同的岩体,时间相差较多;(4)对于无粘结锚索,锚固力将可能损失30%左右。实践证明对于预应力锚固,采用全粘结锚索要比无粘结锚索锚固力损失少。

Study of rock mass deformation around anchorage section of large-tonnage prestressed cable is important to analysis of cable reinforcement mechanism and geotechnical engineering.In this paper,various issues,such as rock deformation,comparison of deformation with observations,long-term loss of prestressed cable anchoring force,etc are studied based on the long-term deformation monitor data of the left abutment block of Lijiaxia arch dam.The results show that the observations of perpendicular profiles reflect the rock mass deformation around anchorage section,and that within a certain distance to this section,rock mass damage is more severe than that of design level.Rock deformation is completed within four or five years that depends on the properties of rock mass,though anchor cable tension is implemented in a short time.In comparison of unbonded and fully-bounded pre-stressed anchors,the former loses about 30% of its anchoring force,while the latter loses much less.