应用于滑坡的拉力型锚索失效机理  

Investigation into Failure Mechanism of Prestressed Anchor Cables Under Concentrated Tension in Contrlling Landslide

作　　者：罗强[1] 李亮[1] 

机构地区：[1]中南大学土木建筑学院,湖南长沙410075

出　　处：《山地学报》2011年第3期348-355,共8页Mountain Research

基　　金：交通部西部交通建设科技项目(编号:2006318802111)~~

摘　　要：拉力型锚索常用于公路边坡支护工程中,在进行锚固体的结构设计时,注浆体与岩石粘结界面的强度往往被高度关注。在广泛调研西南山区失稳破坏的公路边坡时发现,拉力型锚索最为薄弱的部位并非注浆体与岩石粘结界面。因此,设计11种不同配合比的注浆体,将80根拉力型锚索锚固在软岩及硬岩中,采用拉拔试验对锚索的破坏模式进行研究。结果表明:拉力型锚索常见的破坏模式是钢绞线与注浆体之间的脱粘破坏。选择合理的力学计算模型,获得内锚固段两个粘结界面的应力分布弹性解,分析表明:钢绞线与注浆体粘结界面的峰值应力位于锚孔孔口处,应力分布不均匀程度高,致使孔口处的钢绞线注浆体粘结界面首先发生脱粘破坏,脱粘界面以渐进的方式向内锚固段末端传递,最终导致钢绞线从注浆体中旋转拔出。建议上述研究成果在以后的规范修订和锚固工程设计时引起足够的重视。最后,给出了一个钢绞线与注浆体脱粘破坏的工程实例。Prestressed anchor cable under concentrated tension is often applied in supporting projects of road slope,when designing structure of anchorage,the bond strength of interface between grouting and rock is highly concerned,from investigatings on unstable road slope in mountainous area of south-west China,the weakest part of prestressed anchor cable under concentrated tension was not the interface between grouting and rock.Therefore,eleven grouting materials with different mixture ratios are designed,in which eighty prestressed anchor cables under concentrated tension are embedded in soft rock and hard rock.Then the failure mode of prestressed anchor cables have been obtained by pull-out tests in laboratory.The test results indicate that the dominant failure model of prestressed anchor cable under concentrated tension is debonding along the cable-grouting material interface.The paper abtains the elastic solution of stress distribution on two bond interfaces of embedment section via rational mechanical computation mode.The analyses demonstrate that the peak stress of bond interface between cable and grouting is located at the hole-top of anchorage hole,the stress distribution is highly uneven,which causes debonding of the cable-grouting material interface of hole-top first,the debonding interface transfers to the end of embedment section in progress and finally draw out the cable from the grouting.It should be attach great importance to the study results mentioned above in the design of anchorage engineering and revision of technical specification for prestressed anchor cables in the future.

关 键 词：岩石力学 拉力型锚索 破坏模式 应力分布 失效机理 

分 类 号：P642.22[天文地球—工程地质学] U417[天文地球—地质矿产勘探]