摘要
受开挖施工及锚固地层的影响,基坑锚索预应力损失现象较为普遍。依托某实际工程开展现场试验,分析了张拉荷载大小、张拉锁定方式、无黏结段长度以及循环加载对锚索预应力损失产生的影响,进而对基坑锚索预应力损失形成机制进行了探讨。结果表明:锚索锚固体与周围地层发生的脱黏滑移是产生预应力损失的重要原因,锚拉力越大,锚索预应力损失越明显;对于分散型锚索,单根张拉锁定有利于减少其预应力损失;锚索无黏结段长度会对锚头刚度产生影响,其长度越短,锚索预应力损失越明显;多次循环加载可以将锚固体受荷产生的塑性变形进一步锁定,从而大大降低锚索在锁定后的预应力损失。相关规律和结论可为基坑锚索的设计与施工提供有益的参考。
The occurrence of the prestress loss of anchor cable is more commonly encountered in foundation pit due to the influences of the excavation and strength of the stratum. Field tests were carried out in a practical project to analyze the effects of the tension load, tension locking mode, length of unbonded segment and cyclic loading on the prestress loss of anchor cable. The occurrence mechanism of the prestressed loss of the anchor cable was discussed. The results show that the debonding slip between the anchored solid and the surrounding stratum is an important reason for the prestress loss. A greater anchor force will induce more substantial loss of the prestress. As for the dispersed anchor cables, single tension locking is beneficial for minimizing the prestress loss. The length of the unbonded segment has an effect on the stiffness of the anchor head:a shorter length of the unbonded segment will result in more substantial loss of the prestress. Furthermore, it is found that the plastic deformation of the anchorage will be further locked under more times of cyclic loadings, which as a result reduces the loss of the prestress. The relevant rules and conclusions can provide useful references for the design and construction of the foundation pit anchorage cable.
作者
余瑜
刘新荣
刘永权
YU Yu;LIU Xin-rong;LIU Yong-quan(School of Civil Engineering,Chongqing University,Chongqing 400045,China;Key Laboratory of New Technology for Construction of Cities in Mountain Area Ministry of Education,Chongqing University,Chongqing 400045,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2019年第5期1932-1939,共8页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.41372356)
supported by the National Natural Science Foundation of China(41372356)
关键词
基坑工程
预应力锚索
预应力损失
现场试验
脱黏滑移
foundation pit
prestressed anchor cable
prestress loss
field test
debonding slip
