基坑锚索预应力损失规律现场试验研究
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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.
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.
引文
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[8]BRAHIM B,MOHAMED C,HAIXUE X.Long-term service behavior of cement grounted anchors in the laboratory and field[C]//Anchors in Theory and Pratice.Rotterdam:A.A.Balkema.1995:396-403.
[9]陈安敏,顾金才,沈俊,等.软岩加固中锚索张拉吨位随时间变化规律的模型试验研究[J].岩石力学与工程学报,2002,21(2):251-256.CHEN An-min,GU Jin-cai,SHEN Jun,et al.Model test study on tensioning tonnage of anchorage cable with time in soft rock reinforcement[J].Chinese Journal of Rock Mechanics and Engineering,2002,21(2):251-256.
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[11]王清标.不同岩性条件下预应力锚索锚固力损失规律研究[J].工程地质学报,2012,20(5):849-853.WANG Qing-biao.Features of anchoring force loss in pre-stressed anchor cable under different lithologies[J].Journal of Engineering Geology,2012,20(5):849-853.
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[13]何志宇,叶观宝,高彦斌,等.软土堤岸支护锚索预应力损失特征研究[J].路基工程,2011(3):19-22.HE Zhi-yu,YE Guan-bao,GAO Yan-bin,et al.Study on the characteristics of prestress loss of anchorage cable on soft soil embankment[J].Subgrade Engineering,2011(3):19-22.
[14]王渭明,曹正龙,王刚刚,等.厚冲积层锚索预应力损失研究[J].岩土工程学报,2014,36(9):1607-1613.WANG Wei-ming,CAO Zheng-long,WANG Gang-gang,et al.Prestress loss of anchor cables in thick alluvial clay[J].Chinese Journal of Geotechnical Engineering,2014,36(9):1607-1613.
[15]杨志红,郭忠贤.深基坑加固锚索预应力荷载变化规律的监测分析[J].岩土工程学报,2012,34(增刊1):145-148.YANG Zhi-hong,GUO Zhong-xian.Monitoring analysis of pre-stressed load of anchor cables for deep excavations[J].Chinese Journal of Geotechnical Engineering,2012,34(Suppl.1):145-148.
[16]刘波,张功,周浩亮,等.饱和粉细砂层锚索预应力变化规律监测分析[J].岩土力学,2014,35(增刊1):347-352.LIU Bo,ZHANG Gong,ZHOU Hao-liang,et al.Monitoring and analysis of variation of anchor prestress in saturated silty sand condition[J].Rock and Soil Mechanics,2014,35(Suppl.1):347-352.
[17]刘新荣,刘永权,康景文,等.基坑锚索预应力损失规律及分步张拉控制措施研究[J].岩土工程学报,2015,37(10):1794-1801.LIU Xin-rong,LIU Yong-quan,KANG Jing-wen,et al.Prestress loss laws of anchor cables in foundation pits and control measures of tension by steps[J].Chinese Journal of Geotechnical Engineering,2015,37(10):1794-1801.
[18]刘永权,刘新荣,杨忠平,等.不同类型预应力锚索锚固性能现场试验对比研究[J].岩石力学与工程学报,2016,35(2):275-283.LIU Yong-quan,LIU Xin-rong,YANG Zhong-ping,et al.Field test on anchorage performance of different types of prestressed cables[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(2):275-283.
[19]尤春安.锚固系统应力传递机制理论及应用研究[D].济南:山东科技大学,2004.YOU Chun-an.Theory and application study on stress-transfer mechanism of anchoring system[D].Ji’nan:Shandong University of Science and Technology,2004.
[2]王鸿运,姚小波,张尧,等.基于双排桩和锚索支护基坑开挖监测分析[J].岩土工程学报,2014,36(增刊2):446-450.WANG Hong-yun,YAO Xiao-bo,ZHANG Yao,et al.Monitoring and analysis of excavation based on supporting structures of double-row piles and prestressed anchor cables[J].Chinese Journal of Geotechnical Engineering,2014,36(Suppl.2):446-450.
[3]孙长军,张顶立,刘井学,等.北京地铁车站地连墙支护结构受力变形特性研究[J].岩土工程学报,2015,37(增刊1):78-83.SUN Chang-jun,ZHANG Ding-li,LIU Jing-xue,et al.Mechanical and deformation characteristics of diaphragm wall system of Beijing metro station[J].Chinese Journal of Geotechnical Engineering,2015,37(Suppl.1):78-83.
[4]唐孟雄.基坑工程预应力锚索锚固力试验研究[J].岩石力学与工程学报,2007,26(6):1158-1163.TANG Meng-xiong.Test study on anchorage force of pre-stressed anchor cables for foundation pit[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(6):1158-1163.
[5]熊智彪,王启云,陈振富,等.深基坑桩锚支护结构土层预应力锚索工作性能测试分析[J]安全与环境学报,2008,84(3):101-104.XIONG Zhi-biao,WANG Qi-yun,CHEN Zhen-fu,et al.On the working performance testing and analysis with the pre-stressed anchor rope in the soil in deep foundation pit[J].Journal of Safety and Environment,2008,84(3):101-104.
[6]景锋,余美万,边智华,等.预应力锚索预应力损失特征及模型研究[J].长江科学院院报,2007,24(5):52-55.JING Feng,YU Mei-wan,BIAN Zhi-hua,et al.Study on the characteristics and model of prestress loss of prestressed anchorage cable[J].Journal of Yangtze River Scientific Research Institute,2007,24(5):52-55.
[7]余开彪,程凯兵,杨明亮.预应力锚索预应力损失研究[J].岩土力学,2005,26(增刊2):159-162.YU Kai-biao,CHEN Kai-bing,YANG Ming-lang.Study on prestress loss of prestressed anchor cable[J].Rock and Soil Mechanics,2005,26(Suppl.2):159-162.
[8]BRAHIM B,MOHAMED C,HAIXUE X.Long-term service behavior of cement grounted anchors in the laboratory and field[C]//Anchors in Theory and Pratice.Rotterdam:A.A.Balkema.1995:396-403.
[9]陈安敏,顾金才,沈俊,等.软岩加固中锚索张拉吨位随时间变化规律的模型试验研究[J].岩石力学与工程学报,2002,21(2):251-256.CHEN An-min,GU Jin-cai,SHEN Jun,et al.Model test study on tensioning tonnage of anchorage cable with time in soft rock reinforcement[J].Chinese Journal of Rock Mechanics and Engineering,2002,21(2):251-256.
[10]KIM N K.Performance of tension and compression anchors in weathered soil[J].Journal of Geotechnical and Geoenvironmental Engineering,2003,129(12):1138-1150.
[11]王清标.不同岩性条件下预应力锚索锚固力损失规律研究[J].工程地质学报,2012,20(5):849-853.WANG Qing-biao.Features of anchoring force loss in pre-stressed anchor cable under different lithologies[J].Journal of Engineering Geology,2012,20(5):849-853.
[12]周永江,何思明,杨雪莲.预应力锚索预应力损失机制研究[J].岩土力学,2006,27(8):1353-1356.ZHOU Yong-jiang,HE Si-ming,YANG Xue-lian.Study on prestress loss of anchor cables under long-term loading[J].Rock and Soil Mechanics,2006,27(8):1353-1356.
[13]何志宇,叶观宝,高彦斌,等.软土堤岸支护锚索预应力损失特征研究[J].路基工程,2011(3):19-22.HE Zhi-yu,YE Guan-bao,GAO Yan-bin,et al.Study on the characteristics of prestress loss of anchorage cable on soft soil embankment[J].Subgrade Engineering,2011(3):19-22.
[14]王渭明,曹正龙,王刚刚,等.厚冲积层锚索预应力损失研究[J].岩土工程学报,2014,36(9):1607-1613.WANG Wei-ming,CAO Zheng-long,WANG Gang-gang,et al.Prestress loss of anchor cables in thick alluvial clay[J].Chinese Journal of Geotechnical Engineering,2014,36(9):1607-1613.
[15]杨志红,郭忠贤.深基坑加固锚索预应力荷载变化规律的监测分析[J].岩土工程学报,2012,34(增刊1):145-148.YANG Zhi-hong,GUO Zhong-xian.Monitoring analysis of pre-stressed load of anchor cables for deep excavations[J].Chinese Journal of Geotechnical Engineering,2012,34(Suppl.1):145-148.
[16]刘波,张功,周浩亮,等.饱和粉细砂层锚索预应力变化规律监测分析[J].岩土力学,2014,35(增刊1):347-352.LIU Bo,ZHANG Gong,ZHOU Hao-liang,et al.Monitoring and analysis of variation of anchor prestress in saturated silty sand condition[J].Rock and Soil Mechanics,2014,35(Suppl.1):347-352.
[17]刘新荣,刘永权,康景文,等.基坑锚索预应力损失规律及分步张拉控制措施研究[J].岩土工程学报,2015,37(10):1794-1801.LIU Xin-rong,LIU Yong-quan,KANG Jing-wen,et al.Prestress loss laws of anchor cables in foundation pits and control measures of tension by steps[J].Chinese Journal of Geotechnical Engineering,2015,37(10):1794-1801.
[18]刘永权,刘新荣,杨忠平,等.不同类型预应力锚索锚固性能现场试验对比研究[J].岩石力学与工程学报,2016,35(2):275-283.LIU Yong-quan,LIU Xin-rong,YANG Zhong-ping,et al.Field test on anchorage performance of different types of prestressed cables[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(2):275-283.
[19]尤春安.锚固系统应力传递机制理论及应用研究[D].济南:山东科技大学,2004.YOU Chun-an.Theory and application study on stress-transfer mechanism of anchoring system[D].Ji’nan:Shandong University of Science and Technology,2004.
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