- 摘 要
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（1 蘭州理工大學土木工程學院， 蘭州 730050； 2 后勤工程學院建筑工程系， 重慶 400041）
［摘要］通過對西寧火車站深基坑樁錨支護結(jié)構(gòu)樁身內(nèi)力進行現(xiàn)場實測，分析了不同工況下樁錨式支護樁的受力特性及其變化規(guī)律。結(jié)果表明：冠梁不僅能使樁頂部分受力特性不同于上端自由的直立桿件，而且可以有效減小樁身內(nèi)力；樁錨式支護樁樁身鋼筋應力實測值遠小于鋼筋強度設計值；懸臂支護階段樁身最大彎矩位于基坑底面附近，樁錨支護階段樁身最大彎矩位于基坑底面以上至1/3基坑深度的區(qū)域內(nèi)；支護樁嵌固深度過長并不能改善支護樁的受力特性；對于樁錨支護結(jié)構(gòu)，用極限平衡法與彈性支點法進行計算都是偏于安全的，在基坑底面以上，設計時采用極限平衡法比彈性支點法更為經(jīng)濟，而在基坑底面以下采用彈性支點法得出的結(jié)果與實測值更加吻合；支護樁樁頂側(cè)向位移隨基坑開挖深度的增大而增大，設置預應力錨桿能有效控制基坑頂部側(cè)向位移的發(fā)展。
［關(guān)鍵詞］深基坑; 支護樁; 內(nèi)力; 彎矩
中圖分類號：TU473 文獻標識碼：A 文章編號：1002-848X(2014)17-0063-06
Experimental study on internal force of retaining piles in pile-anchor supporting structure
Huang Xuefeng1,2, Chen Shuaiqiang1, Ma Long1, Kong Yang1
(1 Department of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, China; 2 Department of Civil Engineering, Logistic Engineering University, Chongqing 400041, China)
Abstract: Through the field measurement of the internal force of retaining piles in pile-anchor supporting structure of the deep foundation pit in Xining railway station, mechanical performance and changing laws of the internal force were studied under different working conditions. The results show that the capping beam can make the mechanical performance of the pile top quite different from that of the upright free head shaft and effectively reduce the internal force. The measured reinforcement stress value of retaining piles in pile-anchor supporting structure is far less than its design value. The maximum bending moment of retaining piles in cantilever supporting phase lies near the bottom of foundation pit, and that of retaining piles in pile-anchor supporting phase lies at the position from one-third depth to the bottom of foundation pit. The mechanical performance of retaining piles can not be improved though deepening the embedded depth of the retaining piles. The limit equilibrium method and elastic fulcrum method are conservative for pile-anchor supporting structure, the limit equibrium method is more economic above the bottom of the foundation pit, while the elastic fulcrum method has good agreement with the measurement under the bottom. The displacement of retaining piles increases with the increase of foundation pit depth, and the lateral displacement of foundation pit is controlled by setting prestressed anchors remarkably.
Keywords: deep foundation pit; retaining pile; internal force; bending moment
作者簡介：黃雪峰，博士，教授，Email：hxfen60@163.com。
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