摘要
单向土工格栅加筋膨胀土技术在治理膨胀土地区堑坡坍滑方面得到了成功的运用,该技术的关键是筋土间的相互作用力,需通过拉拔试验获得。国内外不少学者尝试用数值模拟来获取土中加筋的拉拔力,而模拟所需参数大多采用经验估算或文献获得。由于一些参数取值与实际不符,导致模拟结果与工程实测值有不小误差。目前通过完成系统试验获得所需参数后再做数值模拟的不多,而先做加筋膨胀土拉拔试验,再对其数值模拟的更鲜见。首先用直剪试验获得了膨胀土的抗剪强度指标,然后用自行研发的大型数控拉拔试验系统完成了单向土工格栅加筋膨胀土拉拔试验,取得了数值模拟所需单位面积刚度系数、筋土界面黏结强度及摩擦角等参数,重新设计并进行了带位移监测且改变施测上覆压力的拉拔试验。运用FLAC3D软件,利用其内置的土工格栅单元对试验测试结果进行了数值模拟。通过对拉拔力、监测位移的模拟结果与试验实测数值间的对比发现:两者误差较小,表明将数值模拟法用于预测加筋膨胀土试验中筋材的拉拔力及位移可行,能方便获取筋土间应力、应变的发生、发展与变化,可减少做拉拔试验的经济和时间成本,为加筋机理研究提供了一种快速便捷的研究方法。
The technology of uniaxial geogrid reinforced expansive soil has been successfully applied in the treatment of cutting slope collapse in the expansive soil area.The key of the technology is the interaction between reinforcement and soil,which needs to be obtained through pullout test.Many scholars at home and abroad have tried to use numerical simulation to obtain the pullout force of the reinforcement in the soil,and most of the parameters required for simulation are obtained by empirical estimation or literature.Because some parameters are not consistent with the actual values,there is large error between simulation result and measured value.At present,few numerical simulations are done after obtaining the required parameters through system test,and it is rare to do the pullout test on reinforced expansive soil at first and then the numerical simulation.First,the shear strength indicator of the expansive soil is obtained by direct shear test,and then the pullout test of uniaxial geogrid reinforced expansive soil is completed by a self developed large-scale numerical control pullout test system.The parameters such as stiffness coefficient per unit area,bond strength of reinforced soil interface and friction angle required for numerical simulation are obtained,and the pullout test with displacement monitoring and change of overburden pressure is redesigned and carried out.The test result is simulated by using FLAC3 D software and its geogridSEL unit.By comparing the pullout force and the monitored displacement between the simulation result and the measured values,it is found that the error between them is small,which indicates that it is feasible to use numerical simulation method to predict the pullout force and displacement of the reinforcement in reinforced expansive soil test.The occurrence,development and change of stress and strain between reinforcement and soil can be easily obtained,the economic and time costs of pullout test can be reduced,and it provides a fast and convenient method for the study of reinforcement mechanism.
作者
万亮
杨和平
WAN Liang;YANG He-ping(Key Laboratory of Road Structure and Material of Ministry of Transport,Changsha University of Science and Technology,Changsha Hunan 410076,China;Anhui Agricultural Reclamation Group Co.,Ltd.,Hefei Anhui 230000,China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2020年第2期31-39,共9页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(50978035,51608053)
道路结构与材料交通行业重点实验室开放基金项目(kfj100208).
关键词
道路工程
数值模拟
拉拔试验
土工格栅
膨胀土
road engineering
numerical simulation
pullout test
geogrid
expansive soil
