摘要
第二代负泊松比(second-generation negative Poisson’s ratio bolts,2G-NPR)锚杆逐渐应用于裂隙岩体加固,为研究2G-NPR锚杆在充填结构面中的抗剪性能,采用室内直剪试验对比分析了不同充填厚度下2G-NPR锚杆和普通钢筋(Q235)锚杆锚固结构面的剪切力学行为。结果表明,相同充填厚度下,2G-NPR锚杆较Q235锚杆弹性阶段剪切刚度低,峰值抗剪强度高、峰值剪切位移大;随着充填厚度增加,虽然两类锚杆的峰值抗剪强度变化相差不大,但由于2G-NPR锚杆的高吸能、高延展特性,其峰值剪切位移优势明显,使得试样延性得到一定提升。锚杆轴力监测数据表明,2G-NPR锚杆能够有效补偿其与灌浆体解耦造成的轴力突降,且持荷能力更持久;其平均峰值轴力为Q235锚杆的3.17倍,且随着充填厚度增加,峰值轴力持续上升,锚固性能更为稳定。进一步结合声发射监测发现,相同充填厚度下,2G-NPR锚杆的最大累计计数和最大累计能量更低,b值(声发射小事件数与大事件数的比值)下降时间更晚,试样破坏程度更小,揭示2G-NPR锚杆提升试样延性的原因在于其有效吸收了剪切应变能,减缓了裂纹的扩展。研究结果可为2G-NPR锚杆在软硬互层岩体支护工程中的应用提供指导。
The second-generation negative Poisson’s ratio(2G-NPR)bolts are increasingly being applied in the reinforcement of fractured rock masses.Direct shear tests were conducted to compare and analyze the shear mechanical behaviors of 2G-NPR anchor bolts and conventional steel(Q235)bolts in anchored joints with different filling thicknesses.The results showed that,under the same filling thickness,the 2G-NPR bolts exhibited lower shear stiffness in the elastic stage,higher peak shear strength,and greater peak shear displacement compared to the Q235 bolts.As the filling thickness increased,although the changes in peak shear strength between the two types of anchor bolts were not significantly different,the 2G-NPR bolts displayed a notable advantage in peak shear displacement due to their high energy absorption and high ductility characteristics,resulting in improved specimen ductility.Axial force monitoring data revealed that the 2G-NPR bolts effectively compensated for the sudden axial force drop caused by decoupling with the grout and demonstrated more sustained load-bearing capacity.Their average peak axial force was 3.14 times that of Q235 bolts,and the peak axial force continued to increase with the filling thickness,indicating more stable anchoring performance.Acoustic emission(AE)monitoring further revealed that,under the same filling thickness,the 2G-NPR bolts had lower maximum cumulative counts and maximum cumulative energy,with a later decrease in the b-value(the ratio of small to large AE events),leading to less damage to the specimens.This indicates that the enhanced ductility of the specimens reinforced by 2G-NPR bolts is due to their effective absorption of shear strain energy,which slows the propagation of cracks.These findings provide guidance for the application of 2G-NPR bolts in supporting rock masses with weak interlayers.
作者
黄曼
宁昊晟
洪陈杰
陶志刚
刘雨星
张贺
HUANG Man;NING Hao-sheng;HONG Chen-jie;TAO Zhi-gang;LIU Yu-xing;ZHANG He(School of Civil Engineering,Shaoxing University,Shaoxing,Zhejiang 312000,China;Key Laboratory of Rock Mechanics and Geological Hazards of Zhejiang Province,Shaoxing University,Shaoxing,Zhejiang 312000,China;School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)
出处
《岩土力学》
北大核心
2025年第S1期131-140,共10页
Rock and Soil Mechanics
基金
国家自然科学基金(No.42272333,No.42377154)
作者简介
第一作者:黄曼,男,1983年生,博士,教授,主要从事岩体结构面力学性质等方面的研究工作。E-mail:hmcadx@126.com;通讯作者:洪陈杰,男,1994年生,博士研究生,主要从事岩体结构面力学性质方面的研究工作。E-mail:hongchenjie66@163.com
