扩底参数对原状土掏挖基础抗拔影响的敏感性研究  

Sensitivity Study of Structural Enlarged Base Parameters on Uplift Bearing Capacity for Digged Foundations

作　　者：鲁先龙[1] 郑卫锋[1] 童瑞铭[1] 崔强[1] 

机构地区：[1]中国电力科学研究院,北京100192

出　　处：《中国电力》2016年第8期41-44,58,共5页Electric Power

基　　金：国家电网公司科技资助项目(GCB17201500216)~~

摘　　要：扩底是提高掏挖基础的抗拔承载性能的常用方法,但随着掏挖基础埋深和扩底直径的增大,扩底部分在基础混凝土量中所占的比例不断增加,且扩底已成为掏挖基础施工的难点和危险点。选取深径比、基底扩展角和立柱直径3个影响参数,采用Taguchi正交试验方法设计了3因素3水平的9个试验基础,分别在甘肃3个戈壁和1个黄土地基的4个试验场地完成了36个扩底掏挖基础抗拔现场试验。根据现场试验结果,基于Taguchi方法研究了深径比、扩展角和立柱直径3个因素对扩底掏挖基础抗拔承载性能影响规律。结果表明:基础周围地基土体强度是影响扩底掏挖基础抗拔性能的决定性因素。戈壁和黄土地基中掏挖基础的抗拔极限承载性能均随深径比、基底扩展角和立柱直径的增加而增加,但其对基础抗拔承载性能影响的敏感性不同,戈壁地基扩底参数影响敏感性由大到小依次为深径比、立柱直径和基底扩展角,而黄土地基扩底参数敏感性由大到小依次为基底扩展角、立柱直径和深径比。Base enlargement is a widely used method to improve uplift performance of digged foundations of transmission towers. The portion of concrete amount of enlarges base increases with the increasing of embeddment and bell diameter of tower foundation. Furthermore, base enlargement is difficult and dangerous during construction. Taguchi method is applied to investigate effect of structural parameters of enlarged base on uplift load bearing capacity of the digged foundations. The selected structural parameters are embedment to bell diameter ratio, angle of the conical surface against the vertical and shaft diamter. A orthogonal array is selected and 9 digged foundations are designed according to Taguchi method with those three factors and corresponding three levels. Thirty-six field tests are performed at four sites in Gansu province including three Gobi gravel sites and one loess site. Analysis of signal-to-noise （S/N） ratio and analysis of variance （ANOV） methods are used to evaluate testing results. The results show that soil strength is the decisive factors for ultimate uplift eapactiy of digged foundations for transmission towers. The uplift performance improves when each of three structural parameters mentioned above increases. However, sensitivities of these factors are different for the foundations embedded in different grounds. In Gobi gravel, the senstivities in ascending order are embedment to bell diameter ratio, shaft diamter, and angle of the conical surface against the vertical. In loess soil, senstivities for the same sequence are in descending order.

关 键 词：输电线路 杆塔基础 掏挖基础 上拔 扩底 Taguchi方法 正交试验 荷载-位移曲线 方差分析 

分 类 号：TM75[电气工程—电力系统及自动化]