摘要
新型多节泡土钉具有拉拔硬化特征,相比传统土钉,其在土质边坡中抗拔性能更优。为了探究实际工况条件下新型多节泡土钉的边坡加固性能,并与传统土钉进行比较,开展7组新型多节泡土钉及传统土钉现场循环张拉试验,研究注浆工艺、节泡间距及埋深对土钉抗拔力及其发挥速率的影响规律,进而探明了每一循环下土钉弹、塑性拉拔位移占比,并分析其内在机理。试验结果表明:循环张拉作用下,注浆工艺对土钉的抗拔力影响显著,采用改进式压密注浆工艺和直接压密注浆工艺的土钉抗拔力远远超出传统注浆工艺,且初期的拉拔硬化现象更明显。采用改进式压密注浆工艺的土钉抗拔力发挥速率最快,直接压密注浆工艺次之,传统注浆工艺最小。从总体趋势上看,新型多节泡土钉抗拔力发挥速率在降低,传统土钉抗拔力发挥速率在升高。采用改进式压密注浆工艺虽然不能提升土钉弹性拉拔位移的占比,却能显著提高极限抗拔力;节泡间距对多节泡土钉抗拔力和抗拔力发挥速率影响较小,主要受到土钉周围土体强度的影响;埋深影响多节泡土钉的极限抗拔力,埋深越大,极限抗拔力和初始抗拔力发挥速率越大,同时抗拔力发挥速率随拉拔位移递减的趋势也更加明显。研究成果对提高新型多节泡土钉加固性能和优化工程应用提供指导。
Compared with the traditional soil nails,the new soil nails with multiple bulbs have the characteristics of pulling-out hardening,and its pull-out behaviors in soil slope performance better.In order to explore the slope reinforcement effect of the soil nail with multiple bulbs under actual work conditions and compare it with that of traditional soil nail,seven groups of new and traditional soil nails field cycle tension tests were carried out.The effects of grouting technique,bulb spacing and buried depth on the pull-out force and its effective rate of soil nails were studied.Furthermore,the proportion of elastic and plastic pull-out displacement of soil nails under each cycle was investigated,and its internal mechanism was analyzed.The test results show that the grouting technique has a significant effect on the pull-out force of soil nails under cyclic tension.The pull-out force of soil nails with improved compaction grouting technique and direct compaction grouting technique is far beyond the traditional one,and the hardening phenomenon at the initial stage of pulling-out is more obvious.The soil nails with improved compaction grouting technique have the largest effective rate of pull-out force,followed by the direct compaction grouting technique,and the traditional one is the smallest.From the overall trend,the effective rate of pull-out force of new soil nails is decreasing,and the traditional one is increasing.Although the improved compaction grouting technique cannot increase the proportion of elastic pull-out displacement of soil nails,it can significantly improve the ultimate pull-out force.The bulb space distance has little effect on the pull-out force and the effective rate of pull-out force of the soil nail with multiple bulbs,which is mainly affected by the strength of surrounding soils.The buried depth affects the ultimate pull-out force of the soil nail with multiple bulbs,and a larger of the buried depth leads to the greater of the ultimate pull-out force and the faster rate of the initial pullout force.And the trend of the effective rate of pull-out force decreasing with the pull-out displacement is more obvious.The results can provide guidance for improving the reinforcement performance of the soil nail with multiple bulbs and optimizing the engineering application.
作者
叶新宇
时一帆
李煜
张升
田奔
刘蔚
YE Xinyu;SHI Yifan;LI Yu;ZHANG Sheng;TIAN Ben;LIU Wei(School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2024年第3期1037-1046,共10页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(52008401)
湖南省自然科学基金资助项目(2021JJ40770)
中南大学中央高校基本科研业务费专项资金资助项目(2023ZZTS0186)。
关键词
土钉
拉拔硬化
循环张拉
多节泡
现场试验
soil nail
pull-out hardening
cyclic pull-out
multiple bulbs
field test
作者简介
通信作者:叶新宇(1989—),男,湖南益阳人,副教授,博士,从事边坡加固、地基处理研究,E−mail:yexinyu113@csu.edu.cn。
