既有-新增排桩双层支挡结构开挖模型试验研究
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摘要
在既有地下室以下增设地下空间,常面临既有支护桩与新增支护桩构成双层支挡结构的开挖工况,这是传统开挖设计方法未涉及的新问题。通过大比尺模型试验,以内外双层支护桩排间距为主要参数,研究其对支护结构性能演变、排间土压力的影响。试验结果表明,随排间距减小,新增支护桩位移与弯矩逐渐增大,由嵌固作用转变为主要受力结构。开挖至既有支护桩失效退出工作后,新增支护桩位移与弯矩突增,最大弯矩点下移。既有支护桩背单位土压力随开挖逐渐减小,达到主动极限状态后主动土压力随排间距增大而增大,并接近朗肯主动土压力分布线。通过各试验桩背主动土压力数据分析拟合,建立了以排间距、土体内摩擦角、桩土摩擦角为参数并考虑土拱效应的既有支护桩背主动土压力预测方法。
Underground space supplement by excavation beneath constructed basement usually encounters the situation that existing and newly-created retaining piles form a double layered retaining structure. This is a new topic that traditional excavation design methods have not involved. This study uses large-scale model tests to investigate the influence of row spacing between the two pile layers on the pile displacement, the pile force and the earth pressure acting on the front-row piles. The analyses show that as the row spacing decreases, both the displacement and the bending moment decrease in the existing piles but increase in the supplementary piles, making the supplementary piles be the principal bearing elements. After the existing retaining piles end service, an abrupt increase in the displacement and bending moment of the supplementary piles is detected while the location of the maximum bending moment is shifted to be deeper. The unit earth pressure imposed on the existing piles gradually decreases as excavation proceeds.When the active limit state is reached, the active earth pressure approaches the distribution mode of the Rankine active earth pressure and its magnitude increases with increasing row spacing. Through the analysis and fitting of the active earth pressure data of each test,a prediction method for the active earth pressure on the existing piles is established with considerations of the spacing of pile rows,the soil friction angle, the pile-soil interface friction angle as well as the soil arching effect.
Underground space supplement by excavation beneath constructed basement usually encounters the situation that existing and newly-created retaining piles form a double layered retaining structure. This is a new topic that traditional excavation design methods have not involved. This study uses large-scale model tests to investigate the influence of row spacing between the two pile layers on the pile displacement, the pile force and the earth pressure acting on the front-row piles. The analyses show that as the row spacing decreases, both the displacement and the bending moment decrease in the existing piles but increase in the supplementary piles, making the supplementary piles be the principal bearing elements. After the existing retaining piles end service, an abrupt increase in the displacement and bending moment of the supplementary piles is detected while the location of the maximum bending moment is shifted to be deeper. The unit earth pressure imposed on the existing piles gradually decreases as excavation proceeds.When the active limit state is reached, the active earth pressure approaches the distribution mode of the Rankine active earth pressure and its magnitude increases with increasing row spacing. Through the analysis and fitting of the active earth pressure data of each test,a prediction method for the active earth pressure on the existing piles is established with considerations of the spacing of pile rows,the soil friction angle, the pile-soil interface friction angle as well as the soil arching effect.
引文
[1]马景月.城市地下空间与开发利用规划[J].地下空间,2002,22(3):200-208.MA Jing-yue.Urban underground space and development planning[J].Chinese Journal of Underground Space,2002,22(3):200-208.
[2]申永江,杨明,项正良.双排长短组合桩与常见双排桩的对比研究[J].岩土工程学报,2015,37(2):96-100.SHEN Yong-jiang,YANG Ming,XIANG Zheng-liang.Comparative study on double-row piles with different lengths of several common anti-slide piles[J].Chinese Journal of Geotechnical Engineering,2015,37(2):96-100.
[3]俞峰,刘念武,房凯.软黏土中双排微型桩围护结构的开挖过程性能分析[J].岩石力学与工程学报,2013,32(2):4139-4148.YU Feng,LIU Nian-wu,FANG Kai.Excavation-induced behavior of retaining structure using double-rowed micropiles in soft clay[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(2):4139-4148.
[4]王星华,谢李钊,章敏.深基坑开挖中双排桩支护的数值模拟及性状[J].中南大学学报,2014,45(2):596-602.WANG Xing-hua,XIE Li-zhao,ZHANG Min.Numerical simulation and characteristic of a double-row piles retaining structure for deep excavation[J].Journal of Central South University,2014,45(2):596-602.
[5]郑刚,聂东清,程雪松,等.基坑分级支护的模型试验研究[J].岩土工程学报,2017,39(5):785-793.ZHENG Gang,NIE Dong-qing,CHENG Xue-song,et al.Experimental study on multi-bench retaining foundation pit[J].Chinese Journal of Geotechnical Engineering,2017,39(5):785-793.
[6]朱建明,林庆涛,高晓将.临近地下室外墙影响下的挡土墙空间土压力研究[J].岩土力学,2016,37(12):3417-3426.ZHU Jian-ming,LIN Qing-tao,GAO Xiao-jiang,et al.Research on space earth pressure behind retaining wall adjacent to existing basements exterior wall[J].Rock and Soil Mechanics,2016,37(12):3417-3426.
[7]杨明辉,戴夏斌,赵明华,等.曲线滑裂面下有限宽度填土主动土压力计算[J].岩土力学,2017,38(7):2029-2035.YANG Ming-hui,DAI Xia-bin,ZHAO Ming-hua,et al.Calculation of active earth pressure for limited soils with curved sliding surface[J].Rock and Soil Mechanics,2017,38(7):2029-2035.
[8]FRYDMAN S,KEISSAR I.Earth pressures on retaining walls near rock faces[J].Journal of Geotechnical Engineering,ASCE,1987,113(6):586-599.
[9]TAKE W A,VALSANGKAR A J.Earth pressures on unyielding retaining walls of narrow backfill width[J].Canadian Geotechnical Journal,2001,38(11):1220-1230.
[10]邱仓虎,詹永勤,秦玉康,等.北京市音乐堂改扩建工程的结构设计[J].建筑科学,1999,15(6):28-32.QIU Cang-hu,ZHAN Yong-qin,QIN Yu-kang,et al.Structural design of the reconstruction and expansion project of Beijing music hall[J].Building Science,1999,15(6):28-32.
[11]SHAN H F,YU F,XIA T D,et al.Performance of the underpinning piles for basement-supplementing retrofit of a constructed building[J].Journal of Performance of Constructed Facilities,2017,31(4):1-10.
[12]BRIAN S,PAUL J V.Results of monitoring at the British Library excavation[J].Geotechnical Engineering,2013,167(GE2):99-116.
[13]李大鹏,唐德高,闫凤国,等.深基坑空间效应机理及考虑其影响的土应力研究[J].岩土力学,2014,48(9):1632-1639.LI Da-peng,TANG De-gao,YAN Feng-guo,et al.Mechanics of deep excavation,spatial effect and soil pressure calculation method considering its influence[J].Rock and Soil Mechanics,2014,48(9):1632-1639.
[14]谢征兵.既有建筑下挖改造排桩支护体系研究[D].杭州:浙江理工大学,2016.XIE Zheng-bing.Study on soldier-pile retaining system for excavation beneath constructed buildings[D].Hangzhou:Zhejiang Sci-Tech University,2016.
[15]FOURIE A B,POTTAT D M.Comparison of finite element and limiting equilibrium analyses for an embedded cantilever retaining wall[J].Geotechnique,1989,39(2):175-188.
[16]黄雪峰,张蓓,覃小华,等.悬臂式围护桩受力性状与土压力试验研究[J].岩土力学,2015,36(2):340-346.HUANG Xue-feng,ZHANG Bei,QIN Xiao-hua,et al.Experimental investigation on force behavior and earth pressure of cantilever fender pile[J].Rock and Soil Mechanics,2015,36(2):340-346.
[17]郑刚,陈红庆,雷杨,等.基坑开挖反压土作用机制及其简化分析方法研究[J].岩土力学,2007,28(6):1161-1166.ZHENG Gang,CHEN Hong-qing,LEI Yang,et al.AStudy of mechanism of earth berm and simplified analysis method for excavation[J].Rock and Soil Mechanics,2007,28(6):1161-1166.
[18]彭述权,周健,樊玲,等.考虑土拱效应刚性挡墙土压力研究[J].岩土力学,2008,29(10):2701-2707.PENG Shu-quan,ZHOU Jian,FAN Ling,et al.Research on earth pressure of rigid retaining wall considering soil arching[J].Rock and Soil Mechanics,2008,29(10):2701-2707.
[2]申永江,杨明,项正良.双排长短组合桩与常见双排桩的对比研究[J].岩土工程学报,2015,37(2):96-100.SHEN Yong-jiang,YANG Ming,XIANG Zheng-liang.Comparative study on double-row piles with different lengths of several common anti-slide piles[J].Chinese Journal of Geotechnical Engineering,2015,37(2):96-100.
[3]俞峰,刘念武,房凯.软黏土中双排微型桩围护结构的开挖过程性能分析[J].岩石力学与工程学报,2013,32(2):4139-4148.YU Feng,LIU Nian-wu,FANG Kai.Excavation-induced behavior of retaining structure using double-rowed micropiles in soft clay[J].Chinese Journal of Rock Mechanics and Engineering,2013,32(2):4139-4148.
[4]王星华,谢李钊,章敏.深基坑开挖中双排桩支护的数值模拟及性状[J].中南大学学报,2014,45(2):596-602.WANG Xing-hua,XIE Li-zhao,ZHANG Min.Numerical simulation and characteristic of a double-row piles retaining structure for deep excavation[J].Journal of Central South University,2014,45(2):596-602.
[5]郑刚,聂东清,程雪松,等.基坑分级支护的模型试验研究[J].岩土工程学报,2017,39(5):785-793.ZHENG Gang,NIE Dong-qing,CHENG Xue-song,et al.Experimental study on multi-bench retaining foundation pit[J].Chinese Journal of Geotechnical Engineering,2017,39(5):785-793.
[6]朱建明,林庆涛,高晓将.临近地下室外墙影响下的挡土墙空间土压力研究[J].岩土力学,2016,37(12):3417-3426.ZHU Jian-ming,LIN Qing-tao,GAO Xiao-jiang,et al.Research on space earth pressure behind retaining wall adjacent to existing basements exterior wall[J].Rock and Soil Mechanics,2016,37(12):3417-3426.
[7]杨明辉,戴夏斌,赵明华,等.曲线滑裂面下有限宽度填土主动土压力计算[J].岩土力学,2017,38(7):2029-2035.YANG Ming-hui,DAI Xia-bin,ZHAO Ming-hua,et al.Calculation of active earth pressure for limited soils with curved sliding surface[J].Rock and Soil Mechanics,2017,38(7):2029-2035.
[8]FRYDMAN S,KEISSAR I.Earth pressures on retaining walls near rock faces[J].Journal of Geotechnical Engineering,ASCE,1987,113(6):586-599.
[9]TAKE W A,VALSANGKAR A J.Earth pressures on unyielding retaining walls of narrow backfill width[J].Canadian Geotechnical Journal,2001,38(11):1220-1230.
[10]邱仓虎,詹永勤,秦玉康,等.北京市音乐堂改扩建工程的结构设计[J].建筑科学,1999,15(6):28-32.QIU Cang-hu,ZHAN Yong-qin,QIN Yu-kang,et al.Structural design of the reconstruction and expansion project of Beijing music hall[J].Building Science,1999,15(6):28-32.
[11]SHAN H F,YU F,XIA T D,et al.Performance of the underpinning piles for basement-supplementing retrofit of a constructed building[J].Journal of Performance of Constructed Facilities,2017,31(4):1-10.
[12]BRIAN S,PAUL J V.Results of monitoring at the British Library excavation[J].Geotechnical Engineering,2013,167(GE2):99-116.
[13]李大鹏,唐德高,闫凤国,等.深基坑空间效应机理及考虑其影响的土应力研究[J].岩土力学,2014,48(9):1632-1639.LI Da-peng,TANG De-gao,YAN Feng-guo,et al.Mechanics of deep excavation,spatial effect and soil pressure calculation method considering its influence[J].Rock and Soil Mechanics,2014,48(9):1632-1639.
[14]谢征兵.既有建筑下挖改造排桩支护体系研究[D].杭州:浙江理工大学,2016.XIE Zheng-bing.Study on soldier-pile retaining system for excavation beneath constructed buildings[D].Hangzhou:Zhejiang Sci-Tech University,2016.
[15]FOURIE A B,POTTAT D M.Comparison of finite element and limiting equilibrium analyses for an embedded cantilever retaining wall[J].Geotechnique,1989,39(2):175-188.
[16]黄雪峰,张蓓,覃小华,等.悬臂式围护桩受力性状与土压力试验研究[J].岩土力学,2015,36(2):340-346.HUANG Xue-feng,ZHANG Bei,QIN Xiao-hua,et al.Experimental investigation on force behavior and earth pressure of cantilever fender pile[J].Rock and Soil Mechanics,2015,36(2):340-346.
[17]郑刚,陈红庆,雷杨,等.基坑开挖反压土作用机制及其简化分析方法研究[J].岩土力学,2007,28(6):1161-1166.ZHENG Gang,CHEN Hong-qing,LEI Yang,et al.AStudy of mechanism of earth berm and simplified analysis method for excavation[J].Rock and Soil Mechanics,2007,28(6):1161-1166.
[18]彭述权,周健,樊玲,等.考虑土拱效应刚性挡墙土压力研究[J].岩土力学,2008,29(10):2701-2707.PENG Shu-quan,ZHOU Jian,FAN Ling,et al.Research on earth pressure of rigid retaining wall considering soil arching[J].Rock and Soil Mechanics,2008,29(10):2701-2707.