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(華東建筑設(shè)計(jì)研究院有限公司  上海 20002)
［提要］  上海世博500kV大容量全地下變電站地下建筑直徑(外徑)為130m，地下結(jié)構(gòu)埋置深度34m，正常使用階段采用樁端深度達(dá)82.3m的鉆孔灌注樁作為抗拔基礎(chǔ)。與淺埋的地下工程相比，該深埋地下結(jié)構(gòu)抗拔樁設(shè)計(jì)面臨的特殊問題是如何反映如此大體量深層地下開挖卸荷對(duì)抗拔樁承載特性的影響，主要表現(xiàn)在：深埋地下結(jié)構(gòu)抗拔樁地面試樁開挖段側(cè)摩阻力的扣除；開挖卸荷后樁周土體圍壓減小對(duì)樁基承載力削弱的影響；開挖卸荷基底隆起對(duì)樁產(chǎn)生的預(yù)拉力。介紹了上海世博500kV地下變電站工程超深抗拔樁的設(shè)計(jì)，采用現(xiàn)場(chǎng)試驗(yàn)與有限元方法針對(duì)上述深層開挖帶來的特殊問題進(jìn)行初步的研究與探討。理論分析表明，深層開挖對(duì)抗拔樁承載性能產(chǎn)生了顯著的影響，承載力發(fā)生較大削弱且產(chǎn)生較大的預(yù)拉力。該抗拔樁的設(shè)計(jì)采取了相應(yīng)的對(duì)策。
［關(guān)鍵詞］  地下變電站  抗拔樁  深層開挖  擴(kuò)底樁  注漿  現(xiàn)場(chǎng)試驗(yàn)  雙套管法  卸荷回彈  承載力  損失
Design and Analysis of the Deep Substructures Uplift Piles in the Project of Shanghai World Exposition 500kV Underground Electric Substation/Wang Weidong，Weng Qiping，Wu Jiangbin(East China Architecture Design Institute，Shanghai 200002，China)
Abstract:Shanghai World Exposition 500kV highcapacity underground electric substation has the architectural diameter of 130 meters and buried depth of 34 meters,and during the application stage,the castinplace pile with the depth of 823 meters is used as the uplift foundation.The key problem of uplift piles in deep buried substructure compared to underground engineering with shallow bury depth is how to reflect the influence of deep excavation offloading on the uplift piles bearing characteristic and capacity.The influence mainly includes:deduction of the deep substructure uplift piles side friction resistance in the ground test piles excavated segment,unfavorable action of the bearing capacity from the pressure looseness of soil around the pile and the pretension axial force of piles from the foundation rebound after the excavation. Based on the project of Shanghai World Exposition 500kV underground substation,it has been researched and discussed the three mentioned key problems of bearing uplift piles characteristic in the projects of deep excavation by the field test and finite element method.
Keywords:underground electric substation;uplift pile; deep excavation; bearing characteristic; pedestal uplift pile; subsequent side inject; field test; double tubular method; offload rebound; bearing capacity loss
*上海市科委重點(diǎn)攻關(guān)項(xiàng)目，深層地下結(jié)構(gòu)開發(fā)關(guān)鍵技術(shù)研究(052112010)。