摘要
该文依托穿越砂岩地层的国博车站工程,采用现场预应力锚索拉拔试验和数值模拟方法,揭示了不同工况下锚索端头荷载与位移的关系以及预应力锚索的荷载传力机理,并对依托工程预应力锚索的有效锚固长度进行了优化。研究结果表明:随着拉拔力增大,预应力锚索传力过程分为三个阶段:第一阶段,剪应力集中于锚固段始端,且与拉拔力等比增大;第二阶段,剪应力分布曲线出现波峰,峰值逐步达到极限抗剪力;第三阶段,连续多段锚固段达抗剪极限,剪应力分布最终呈“矩形状”。由实验可得:预应力为200、300和400 kN的锚索对应有效锚固长度分别约5、6和7 m;相比锚索的轴力分布,锚固段剪应力分布对有效锚固长度的确定更准确;预应力锚索的荷载-有效锚固长度曲线呈现由非线性渐趋线性增长规律;采用剪切应力的积分公式计算锚索端头拉拔力,能较好地模拟拉拔试验,锚索端部拉拔荷载随位移的增加呈非线性增大,而增长速率呈逐渐下降趋势。
[Objective]As the excavation depth increases,the tunnel support forms are diversified.Therefore,a study of a prestressed anchor cable is of great significance in tunnel construction applications.However,in existing research on anchor cables,most studies have focused on formation conditions in pebble,broken zone,and loess strata,and systematic research on a prestressed anchor cable in sandstone stratum has not been reported.This paper aims to reveal the relationship between the end load and anchor cable displacement under different working conditions,as well as the load–transfer mechanism of a prestressed anchor cable.It also seeks to optimize the effective anchorage length of the prestressed anchor cable supported by the Guobo Station project so as to provide an effective reference for the design and construction of anchor cables in tunnel engineering.[Methods]In this paper,field prestressed anchor cable pulling tests and numerical simulations are performed.First,the mechanical evolution law of prestressed anchor cable pulling under different anchorage lengths is studied through the field cable pulling test.Then,using FLAC^(3D) finite element numerical simulation technology,the rationality of the field test data and simulation data is compared,the load–transfer mechanism of the prestressed anchor cable is further studied,and the effective anchorage length of the anchor cable under different prestressed conditions is optimized.[Results]The ultimate tensile capacities of the prestressed anchor cable with anchorage section lengths of 5 and 6 m are 509.24 and 611.69 kN,respectively,which provide a certain reference value for the design tensile value of prestressed anchor cables in tunnel design and construction.The effective anchorage lengths of 200,300 and 400 kN prestressed anchor cables are about 5,6,and 7 m,respectively.Compared with the axial force distribution of the cable,the shear stress distribution in the anchorage section is more suitable for determining the effective anchorage length.[Conclusions]Using the integral formula of shear stress to calculate the pulling force of the anchor cable end,a pulling test well can be simulated.The tensile load at the end of the anchor cable increases nonlinearly with an increase in the displacement,but the growth rate decreases gradually.With an increase in the drawing load,the force-transfer mechanism of the prestressed anchor cable is divided into three stages.In the first stage,the shear stress distribution is mainly concentrated at the beginning of the anchorage section,and shear stress is increased proportional to the drawing force.In the second stage,the shear stress distribution in the second half of the anchorage area begins to appear,the curve begins to exhibit obvious peaks,and peak shear stress gradually increases until the ultimate shear capacity per unit length is reached.In the third stage,more anchorage sections reach the shear capacity limit,and the final shear stress distribution shows a“rectangular shape.”When the prestress is less than 400 kN,the curve of the load–effective anchorage length of the prestressed anchor cable completely transitions from nonlinear to linear,and the curve is suitable for studying uniform formation condition with poor soil quality.
作者
王秀博
严志成
王立川
旷文涛
章慧健
杨继康
WANG Xiubo;YAN Zhicheng;WANG Lichuan;KUANG Wentao;ZHANG Huijian;YANG Jikang(CCCC Third Highway Engineering Co.,Ltd.,Beijing 100304,China;Key Laboratory of Transportation Tunnel Engineering,Ministry of Education,School of Civil Engineering,Sichuan Southwest Jiaotong University,Chengdu 610031,China;China Railway 18th Bureau(Group)Co.,Ltd.,Tianjin 300000,China;China Railway Eryuan Engineering Group Co.,Ltd.,Chengdu 610031,China)
出处
《实验技术与管理》
北大核心
2025年第5期140-146,共7页
Experimental Technology and Management
基金
国家自然科学基金项目(52178395)
中铁十八局集团有限公司科技研发项目(G23-02)。
关键词
预应力锚索
现场试验
数值模拟
传力机理
有效锚固长度
prestressed anchor cable
field test
numerical simulation
transfer mechanism of cable
effective anchorage length
