粉土中螺旋锚循环上拔承载特性原位试验研究  

In-Situ Experiments on Cyclic Uplift Bearing Characteristics of Helical Piles in Silt

作　　者：张博 屈讼昭 刘光辉 张斌[3] 马政伟 孙清[3] ZHANG Bo;QU Songzhao;LIU Guanghui;ZHANG Bin;MA Zhengwei;SUN Qing(Electric Power Research Institute of State Grid Henan Electric Power Company,Zhengzhou 450000,China;School of Civil and Transportation Engineering,Henan University of Urban Construction,Pingdingshan 467036,China;Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]国网河南省电力公司电力科学研究院,郑州450000 [2]河南城建学院土木与交通工程学院,河南平顶山467036 [3]西安交通大学,西安710049

出　　处：《工业建筑》2023年第12期204-210,共7页Industrial Construction

基　　金：河南省自然科学基金青年基金项目(222300420105);国网河南省电力公司科技项目(52170222000J);河南城建学院学术技术带头人培养项目(YCJXSJSDTR202202);河南城建学院青年骨干教师培养项目(YCJQNGGJS202101)。

摘　　要：螺旋锚因具有较大的抗拔承载力而被广泛应用于杆塔、风轮发电机其等受循环荷载作用结构物的基础。近年来随着极端强风灾害的增多,螺旋锚已被推广应用于输电线路导线防舞动拉索的锚固设备。然而,目前关于循环荷载作用下螺旋锚承载特性的研究较少,没有关于其承载力计算方法的标准。为此,通过对粉土中螺旋锚开展原位单调及循环加载试验研究,探究螺旋锚循环上拔承载性能。结果表明:螺旋锚在50%静态极限承载力循环作用下,土体达到变形稳定时的累计位移均不大于25 mm;双盘螺旋锚在循环上拔荷载作用下的累计位移最小,约为其他单盘螺旋锚累计位移的一半;当螺旋锚承载力不足时,基础变形急剧增大,并伴随地面出现以螺旋锚为中心的辐射状裂纹;在整个试验过程中,循环荷载作用下的螺旋锚荷载-位移骨架曲线始终低于试验锚静载曲线,循环结束后在静载作用下,两者荷载-位移曲线基本重合;螺旋锚的上拔承载力主要由锚杆侧阻和锚盘端阻两部分组成,螺旋锚在循环上拔荷载作用下,锚杆接触界面的剪切带内土体的累积收缩导致法向应力降低,螺旋锚基础的上拔承载力全部由锚盘提供。Helical piles are widely used in foundations of towers,wind turbine generators and other structures under cyclic loads because of their larger uplift bearing capacities.In recent years,with the increase of extreme strong wind disasters,helical piles have been widely used as anchorage facilities for anti galloping cables of transimission wires in transmission lines.However,there are few studies on the bearing characteristics of helical piles under cyclic loading,and there is no introduction on the bearing capacity calculation method in the relevant regulations and codes.Thus,the monotonic and cyclic in-situ loading tests of helical piles in silt were conducted,the cyclic uplift mechanical characteristics of helical piles were explorated.The results showed that the cumulative displacement of the helical pile was no more than 25 mm when the soil deformation was stable under cyclic action of 50%of static ultimate bearing capacities.The cumulative displacement of helical piles with double helix plates under cyclic uplift loads was smallest,which was about half the cumulative displacement of other helical piles with a single helix plate.When the bearing capacity of helical piles was insufficient,the foundation deformation increased sharply,and a radial crack centered on helical piles appeared on the ground.In the whole test process,the load-displacement skeleton curves of helical piles under cyclic loads were always lower than that of helical piles under static loads.After the cycles,both the load-displacement curves basically coincided under static loads.The uplift bearing capacity of helical piles was mainly composed of side resistance of anchor rods and end resistance of helix plates.Under cyclic uplift loads,the cumulative shrinkage of soil in shear zones of anchor bolt interfaces led to reduction of normal stress,and the uplift bearing capacity of helical piles was provided by helix plates mainly.

关 键 词：螺旋锚 单调及循环荷载 循环上拔承载力 原位试验 

分 类 号：TU476[建筑科学—结构工程]