摘要
风积沙具有结构松散、黏聚力低、稳定性差的特点,在干旱大风环境下,其抗风蚀稳定性差,影响输电线路杆塔基础的稳定性。近年来发展起来的固沙技术可有效改良风积沙的物理力学性质,提高地基承载性能。为研究水泥固化技术对杆塔抗拔基础承载性能及破坏模式的影响,以新疆南部塔克拉玛干沙漠风积沙为研究对象,分别制备出含水率ω为3%、5%的风积沙和水泥含量为4%、6%、8%的水泥固化风积沙填料,通过开展两种地基填料的模型基础上拔试验,获得水泥固化前后模型基础的上拔荷载位移曲线、抗拔极限承载力及破坏模式,并基于数值分析方法解释了地基填料破坏模式的形成机制。结果表明:水泥固化作用可有效提高风积沙地基的刚度,使基础与地基之间的变形更加协调。水泥含量对基础抗拔承载力Tu的影响与其含水率ω有关,ω越大,Tu的提高程度越明显;ω=5%时,Tu随水泥含量增加呈单调递增趋势;ω=3%时,Tu随水泥含量增加呈先提高后降低的变化趋势;水泥含量为6%时,Tu最大,可认为是该含水率条件下水泥含量的最佳配比。水泥固化前后,风积沙地基的破坏模式由张拉剪切组合破坏模式演变为张拉破坏模式。理论分析表明,锚板两侧的地基首先发生屈服,随着上拔荷载增加,屈服范围逐渐向上扩展,地基上部与基础交界面同步发生屈服,并逐渐向下扩展,最终上下塑性区在一定深度处交汇并连通,地基发生破坏。水泥固化前后风积沙填料的直剪试验与SEM测试结果表明:基础抗拔承载力Tu与填料黏聚力c之间满足线性关系,水泥与风积沙颗粒之间形成的胶凝物质改变了风积沙的微观结构,从而影响其变形及承载能力。
With the characteristics of loose structure,low cohesion and poor stability,the aeolian sand is of poor stability against wind erosion under the arid and windy environment,which affects the stability of transmission line tower foundation.Sand consolidation technology developed in recent years can effectively improve the physical and mechanical properties of aeolian sand and improve the bearing capacity of foundation.To study the influence of cement solidification technology on the bearing capacity and failure mode of tower foundation,aeolian sand in the Taklimakan Desert in the south of Xinjiang Province is taken as the research object.The aeolian sands with water contentsωof 3%and 5%,and aeolian sands consolidated with cements which mass percentage are 4%,6%and 8%,as two kinds of stuff materials,are used to form the foundation filler.The load-displacement curves,ultimate uplift bearing capacities and foundation failure modes of test model foundations in above two kinds of fillers were obtained by carrying out the pull-out tests in the laboratory,and the formation mechanism of failure mode of foundation filling was explained based on the numerical analysis method.The test results and theoretical analysis show that the solidification of cement can enhance the stiffness of aeolian sand,which makes the deformations between foundation and aeolian sand more compatible.The influence of cement content on the ultimate uplift bearing capacities Tu of foundations is related to the water contentsωo f aeolian sand,specifically,the largerωis,the greater Tu is,and Tu increases monotonically with the increase of cement content whenω=5%.With the increase of cement content,Tu increase first and then decrease whenω=3%and Tu is maximum while the cement content is 6%.Before and after consolidating the aeolian sand,failure modes of the foundations changed from tensile and shear failure to tensile failure.The theoretical analysis shows that the foundation on both sides of the anchor plate yields first,and with the increase of uplift load,the yield range gradually expands upward.The interface between the upper part of the foundation and the foundation yields synchronously,and gradually expands downward.Finally,the upper and lower plastic zones intersect and connect at a certain depth,and the foundation is destroyed.The results of direct shear tests on the aeolian sand samples before and after consolidating with cement indicates that the ultimate uplift bearing capacities Tu of test foundations and cohesion c of the aeolian sand samples consolidated with cements satisfy linear relationship.SEM observations exhibit that the cementation material filling the spaces of sand particles in the aeolian sand changes microstructures of the aeolian sand,which affects the deformation and uplift resistance of foundations in aeolian sand.
作者
崔强
张飞阳
徐玉波
何金业
周楠
李洋
CUI Qiang;ZHANG Feiyang;XU Yubo;HE Jinye;ZHOU Nan;LI Yang(China Electric Power Research Inst.,Beijing 102401,China;College of Civil Eng.,Hefei Univ.of Technol.,Hefei 230009,China;State Grid Xinjiang Electric Power Co.Ltd.Construction Branch,Urumchi 830001,China;Xinjiang Electric Power Design Inst.Co.Ltd.,China Energy Eng.Grop.,Urumchi 830001,China)
出处
《工程科学与技术》
EI
CAS
CSCD
北大核心
2019年第6期90-100,共11页
Advanced Engineering Sciences
基金
国网新疆电力公司科技项目(GCB11201800899)
关键词
风积沙
水泥固化
上拔试验
抗拔极限承载力
张拉破坏
微观结构
aeolian sand
consolidating with cement
pull-out test
the ultimate uplift bearing capacity
tensile failure
microstructure
