考虑永久位移的锚索框架减震锚头弹簧组件合理刚度研究  

Reasonable stiffness of the spring components of the damping anchor head for the anchor cable frame considering permanent displacement

作　　者：张桐 蒋良潍[1,2] 杨芸 葛学军[3] 张翰文 易梦笔 ZHANG Tong;JIANG Liangwei;YANG Yun;GE Xuejun;ZHANG Hanwen;YI Mengbi(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,Sichuan,China;Key Laboratory of High-Speed Railway Engineering,Ministry of Education,Chengdu 610031,Sichuan,China;China Railway Eryuan Engineering Group Co.,Ltd.,Chengdu 610031,Sichuan,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]高速铁路线路工程教育部重点实验室,四川成都610031 [3]中铁二院工程集团有限责任公司,四川成都610031

出　　处：《地震工程学报》2024年第2期410-420,共11页China Earthquake Engineering Journal

基　　金：国家自然科学(52078435)。

摘　　要：强震作用下预应力框架锚索可能出现内锚段松脱、锚索拉断等震害,在锚头处设置弹簧是一种新型抗震措施,而弹簧刚度的合理选取对改善锚索受力至关重要。建立在锚头处设置弹簧预应力锚索框架的加固基岩-覆盖层边坡三维数值模型,研究边坡在不同峰值加速度、不同持时地震波作用下响应规律,调整锚索-弹簧串联体系等效刚度大小,分析坡体永久位移和锚索轴力减载比随弹簧刚度的非线性变化特征;以控制边坡位移及锚索减载效果为目标,提出弹簧组件的合理刚度确定方法。研究表明:随弹簧刚度降低,缓冲减震作用逐渐显著;坡顶水平加速度受刚度变化影响较小,但当弹簧刚度低于临界值后边坡位移及弹簧变形量急剧增加;以边坡永久位移实际调查经验限值为首要控制条件,结合位移、弹簧峰值行程随刚度变化拟合“直-曲分界点”曲线,以共同确定弹簧刚度下限;同理,依据减载比拟合曲线轴力削减明显区段得出刚度上限,以保证一定工程经济性。针对算例模型取永久位移10 cm、拟合曲线曲率k小于0.002 k max作为直曲分界判断依据,得0.4 g~0.6g强震下弹簧刚度区间为(2.5,3.8)kN/mm,研究方法可为边坡预应力锚固工程抗震设计提供参考。Under the action of a strong earthquake,dynamic damages,such as the pullout of the inner anchor section and the abruption of the anchor cable,are induced by the prestressed anchor cable frame.A novel anti-seismic measure involves setting springs at the outer anchor head,and an important design parameter is the spring stiffness.The seismic responses of slope under various PGAs and seismic waves with different durations were studied using a three-dimensional numerical model of bedrock-overburden slope reinforced by a prestressed anchor cable frame with springs at the anchor head.A method for determining the reasonable stiffness of spring components was proposed to control the displacement of the slope and reduce the load on the anchor cable.Results show that the damping effect gradually emerges with a decrease in spring stiffness.The horizontal acceleration at the top of the slope is slightly affected by the stiffness change.However,the slope displacement and spring deformation sharply increase when the spring stiffness is lower than the critical value.The minimum stiffness is determined by taking the empirical limit of slope permanent displacement as the primary control condition and combining the“straight-curved boundary point”of the fitting curve of spring peak stroke and stiffness.The permanent displacement of 10 cm and delimit curvature k less than 0.002 k max are taken for the calculation model to obtain a reasonable range of spring stiffness,i.e.,(2.5,3.8)kN/mm,under 0.4 g-0.6 g.The proposed method can provide a reference for the seismic design of prestressed anchorage engineering of slopes.

关 键 词：减震弹簧锚头 合理刚度 锚索减载比 永久位移控制 数值模拟 

分 类 号：TU435[建筑科学—岩土工程]