大直径超长桩的承载潜力问题探讨
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摘要
基于入和没入硬层时有限元数值模拟对比分析和持力层不同时同场地现场对比试验资料分析,对大直径超长灌注桩的承载潜力问题进行了探讨.结果表明:(1)大直径超长桩入和没入桩端硬层时其承载性能会有很大区别.桩入硬层后其承载力大大提高,其极限承载力为没入硬层的3.8倍以上;(2)通过桩底注浆使持力层强度提高后,大直径超长桩的承载力大大提高.和注浆前相比,注浆后桩的承载力提高了0.27—1.0倍以上.和非注浆的桩相比,注浆桩的承载力为非注浆桩的1.25—1.61倍以上;(3)有好的天然持力层时,应设法使大直径超长桩进入该持力层;无好的天然持力层时,可进行人工桩底注浆使桩端岩土层强度提高;(4)当大直径超长桩有了好的持力层后,应使桩顶的沉降尽可能的大,这样可使桩的承载潜力充分地发挥出来.
Based on the field loading tests and FEM numerical simulation analysis,the paper probes into the potential bearing capacity of large diameter and super-long bored-cast-place piles.Conclusions are drawn as follows:Firstly,the bearing behavior is different greatly when the pile penetrates into hard soil layer and when it does not.The bearing capacity of the pile is increased greatly—its bearing capacity being 3.8 times as much as the pile that doesn't penetrate into hard soil layer. Secondly,the bearing properties of large diameter and super-long bored-castplace piles is improved greatly after the bearing layer is reinforced by pile bottom grouting.The bearing capacity of pile after the bottom grouting is 0.27—1.0 times greater than the pile' that precedes bottom grouting.The bearing capacity of grouting piles is 1.25—1.61 times as much as that of the non-grouting piles.Thirdly,when there is a strong natural bearing layer, the large diameter and super-long bored-cast-place piles would penetrate into the bearing layer.When there isn't strong natural bearing layer,the bearing properties of pile end soil layer can be enhanced through pile bottom grouting.Finally,with a strong bearing layer,the tip settlement of large diameter and super-long bored-cast-place piles should be as large as possible in order to bring the bearing capacity of pile into fully play.
Based on the field loading tests and FEM numerical simulation analysis,the paper probes into the potential bearing capacity of large diameter and super-long bored-cast-place piles.Conclusions are drawn as follows:Firstly,the bearing behavior is different greatly when the pile penetrates into hard soil layer and when it does not.The bearing capacity of the pile is increased greatly—its bearing capacity being 3.8 times as much as the pile that doesn't penetrate into hard soil layer. Secondly,the bearing properties of large diameter and super-long bored-castplace piles is improved greatly after the bearing layer is reinforced by pile bottom grouting.The bearing capacity of pile after the bottom grouting is 0.27—1.0 times greater than the pile' that precedes bottom grouting.The bearing capacity of grouting piles is 1.25—1.61 times as much as that of the non-grouting piles.Thirdly,when there is a strong natural bearing layer, the large diameter and super-long bored-cast-place piles would penetrate into the bearing layer.When there isn't strong natural bearing layer,the bearing properties of pile end soil layer can be enhanced through pile bottom grouting.Finally,with a strong bearing layer,the tip settlement of large diameter and super-long bored-cast-place piles should be as large as possible in order to bring the bearing capacity of pile into fully play.
引文
[1]邢心魁,吴敏哲,谢异同.样条小波在基桩完整性检测中的应用[J].西安建筑科技大学学报:自然科学版,2004,36(1):25-28.XING Xin-kui.WU Min-zhe,XIE Yi-tong.Application of spline wavelets for pile integrity tesdting[J].J.Xi anUniv.of Arch.&Tech.(Natural Science Edition),2004,36(1):25-28.
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[3]邢心魁,吴敏哲,郑建国.单桩Q-S曲线遗传反分析方法[J].西安建筑科技大学学报:自然科学版,2003,35(1):24-27.XING Xin-kui,WU Min-zhe,ZHENG Jian-guo.Genetic inverse methods onQ-Scurve of single pile loading test[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),2003,35(1):24-27.
[4]燕彬,黄义,潘元.护坡板桩内力计算方法的探讨[J].西安建筑科技大学学报:自然科学版,2003,35(4):398-402.YAN Bin,HUANG Yi,PAN Yuan.Discussions of calculating methods of forces in the bearing piles[J].J.Xi anUniv.of Arch.&Tech.(Natural Science Edition),2003,35(4):398-402.
[5]高忠,熊仲明.膨胀土中桩的胀切力计算研究[J].西安建筑科技大学学报:自然科学版,2003,35(4):412-415.GAO Zhong,XIONG Zhong-ming.Study on the swelling shear of the calculation of piles in swelling soil[J].J.Xi an Univ.of Arch.&Tech.(Naturl Science Edition),2003,35(4):398-402.
[6]熊仲明,赵鸿铁.框架结构在桩-土共同作用下的内力计算分析[J].西安建筑科技大学学报:自然科学版,1999,31(3):288-291.XONG Zhong-ming,ZHAO Hong-tie.Calculating analysis on frame structure in soil-pile interaction[J].J.Xi anUniv.of Arch.&Tech.(Naturl Science Edition),1999,31(1):288-291.
[7]熊仲明,赵鸿铁.地震作用下桩-土共同作用对上部结构的影响分析[J].西安建筑科技大学学报:自然科学版,1999,31(1):44-47.XIONG Zhong-ming,ZHAO Hong-tie.The effect of pile-soil interaction on the upper structure under seismic condt-tions[J].J.Xi an Univ.of Arch.&Tech.(Naturl Science Edition),1999,31(1):44-47.
[8]胡长明,李迪,谢行皓.SPR排桩拱形支护结构的性状分析[J].西安建筑科技大学学报:自然科学版,1999,31(3):280-283.HU Chang-ming,LI Di,XIE Xing-hao.Behavior of arched support of SPR bent Pile[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1999,31(3):280-283.
[9]韩晓雷,黄义.灰土挤密桩成孔过程中孔周土体的应力分析[J].西安建筑科技大学学报:自然科学版,1999,31(3):256-259.HAN Xiao-lei,HUANG Yi.Analysis on the stress of the soil around the hole in hole-formation withli me soil com-paction pile[J].J.Xi an Univ.of Arch.&Tech.(Naturl Science Edition),1999,31(3):256-259.
[10]张献辉,高永贵.自重湿陷性黄土中大直径荷载传递机理试验研究[J].西安建筑科技大学学报:自然科学版,1996,28(4):467-471.ZHANG Xian-hui,GAO Yong-gui.Experi mental study the load transfer mechanism of large diameter pile in loess[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1996,28(4):467-471.
[11]吴仕琴,张保印.高层建筑主桩载荷试验的分析研究[J].西安建筑科技大学学报:自然科学版,1997,29(2):177-182.WU Shi-qin,ZHANG Bao-yin.Discussion on the test result of the bearing capacity of friction filling pile in tallbuildings[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1997,29(2):177-182.
[12]王士川,陈立新,朱晓东.厦门地区沉管灌注桩极限承载力的确定[J].西安建筑科技大学学报:自然科学版,1996,28(4):405-409.WANG Shi-chuan.CHEN Li-xin,ZHU Xiao-dong.Determination of vertical ulti mate carrying capacity of si mplexpiles in Xiamen district[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1996,28(4):405-409.
[13]蒋建平.水下大直径超长桩理论分析与工程应用[D].南京:南京大学,2002.JIANGJian-ping.The theory analysis and engineering application for large diameter and super-long bored-cast-place piles under water[D].Nanjing:Nanjing University,2002.
[14]蒋建平,高广运.大直径超长桩有效桩长的数值模拟[J].建筑科学,2003,19(3):27-29.JIANGJian-ping,GAO Guang-yun.The FEMnumerical si mulation on effective length of large diameter and su-per-long piles[J].Building Science,2003,19(3):27-29.
[15]蒋建平,章杨松,高广运,等.大直径超长灌注桩弹塑性有限元分析[J].力学季刊,2006,(2):45-49.JIANGJian-ping,ZHANG Yang-song,GAO Guang-yun,et al.The elasto-plastic FEMnumerical si mulation onlarge diameter and super-long bored-cast-place piles[J].Mechanics Quarterly,2006,(2):45-49.
[16]蒋建平,汪明武,高广运.桩端岩土差异对超长桩影响的对比研究[J].岩石力学与工程学报,2004,23(18):3190-3195.JIANGJian-ping,WANG Ming-wu,GAO Guang-yun.Contrastive study on influence of difference of pile endrock-soil layer on large diameter and super-long piles[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(18):3190-3195.
[17]龚维明,戴国亮,薛国亚,等.东海大桥超长钻孔灌注桩自平衡试验研究[J].岩土工程界,2004,7(2):40-43.GONG Wei-ming,DAI Guo-liang,XUE Guo-ya,et al.Experi mental study on super-long bored-cast-place piles inDonghai large bridge engineering[J].Geotechnical Engineering World,2004,7(2):40-43.
[18]黄生根,龚维明.苏通长江大桥北引桥二期试桩试验研究[J].工程地质学报,2005,13(1):107-111.HUANG Sheng-gen,GONG Wei-ming.Testing piles for the second state of north bridge approach of Sutong Yan-gtze River[J].Journal of Engineering Geology,2005,13(1):107-111.
[19]王志辉,刘斌,庄平辉.大直径桩端压力注浆桩的承载性状试验[J].东北大学学报:自然科学版,2002,23(2):160-163.WANHZhi-hui,LI U Bin,ZHUANG Ping-hui.Bearing behavior experi mental of bottom-grouting large diameterpore pile[J].Journal of Northeastern University(Natural Science Edition),2002,23(2):160-163.
[20]刘之春,蒋永生,龚维明.大直径扩底桩承载力的沉降变形控制设计法初探[J].东南大学学报:自然科学版,2001,31(4):49-53.LIUZhi-chun,JIANG Yong-sheng,GONG Wei-ming.Study on design method of settlement controllingfor bearing capacityof large diameter belled piles[J].Journal of Southeastern University(Natural Science Edition),2001,31(4):49-53.
[21]张聚山,王俊林.扩底墩基础设计与分析[J].岩土工程学报,1996,18(3):67-73.ZHANG Ju-shan,WANG Jun-lin.The design and analysis of belled piers foundation[J].Chinese Journal ofGeotechnical Engineering,1996,18(3):67-73.
[2]李晓莉,王玲玲,马乐为.地基参数以及结构层数对土-结构相互作用的影响[J].西安建筑科技大学学报:自然科学版,2004,36(3):299-302.LI Xiao-li,WANG Ling-ling,MA Le-wei.Influence of the foundation soil parameters and structural stories on thepile-soil-structure interaction[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),2004,36(3):299-302.
[3]邢心魁,吴敏哲,郑建国.单桩Q-S曲线遗传反分析方法[J].西安建筑科技大学学报:自然科学版,2003,35(1):24-27.XING Xin-kui,WU Min-zhe,ZHENG Jian-guo.Genetic inverse methods onQ-Scurve of single pile loading test[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),2003,35(1):24-27.
[4]燕彬,黄义,潘元.护坡板桩内力计算方法的探讨[J].西安建筑科技大学学报:自然科学版,2003,35(4):398-402.YAN Bin,HUANG Yi,PAN Yuan.Discussions of calculating methods of forces in the bearing piles[J].J.Xi anUniv.of Arch.&Tech.(Natural Science Edition),2003,35(4):398-402.
[5]高忠,熊仲明.膨胀土中桩的胀切力计算研究[J].西安建筑科技大学学报:自然科学版,2003,35(4):412-415.GAO Zhong,XIONG Zhong-ming.Study on the swelling shear of the calculation of piles in swelling soil[J].J.Xi an Univ.of Arch.&Tech.(Naturl Science Edition),2003,35(4):398-402.
[6]熊仲明,赵鸿铁.框架结构在桩-土共同作用下的内力计算分析[J].西安建筑科技大学学报:自然科学版,1999,31(3):288-291.XONG Zhong-ming,ZHAO Hong-tie.Calculating analysis on frame structure in soil-pile interaction[J].J.Xi anUniv.of Arch.&Tech.(Naturl Science Edition),1999,31(1):288-291.
[7]熊仲明,赵鸿铁.地震作用下桩-土共同作用对上部结构的影响分析[J].西安建筑科技大学学报:自然科学版,1999,31(1):44-47.XIONG Zhong-ming,ZHAO Hong-tie.The effect of pile-soil interaction on the upper structure under seismic condt-tions[J].J.Xi an Univ.of Arch.&Tech.(Naturl Science Edition),1999,31(1):44-47.
[8]胡长明,李迪,谢行皓.SPR排桩拱形支护结构的性状分析[J].西安建筑科技大学学报:自然科学版,1999,31(3):280-283.HU Chang-ming,LI Di,XIE Xing-hao.Behavior of arched support of SPR bent Pile[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1999,31(3):280-283.
[9]韩晓雷,黄义.灰土挤密桩成孔过程中孔周土体的应力分析[J].西安建筑科技大学学报:自然科学版,1999,31(3):256-259.HAN Xiao-lei,HUANG Yi.Analysis on the stress of the soil around the hole in hole-formation withli me soil com-paction pile[J].J.Xi an Univ.of Arch.&Tech.(Naturl Science Edition),1999,31(3):256-259.
[10]张献辉,高永贵.自重湿陷性黄土中大直径荷载传递机理试验研究[J].西安建筑科技大学学报:自然科学版,1996,28(4):467-471.ZHANG Xian-hui,GAO Yong-gui.Experi mental study the load transfer mechanism of large diameter pile in loess[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1996,28(4):467-471.
[11]吴仕琴,张保印.高层建筑主桩载荷试验的分析研究[J].西安建筑科技大学学报:自然科学版,1997,29(2):177-182.WU Shi-qin,ZHANG Bao-yin.Discussion on the test result of the bearing capacity of friction filling pile in tallbuildings[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1997,29(2):177-182.
[12]王士川,陈立新,朱晓东.厦门地区沉管灌注桩极限承载力的确定[J].西安建筑科技大学学报:自然科学版,1996,28(4):405-409.WANG Shi-chuan.CHEN Li-xin,ZHU Xiao-dong.Determination of vertical ulti mate carrying capacity of si mplexpiles in Xiamen district[J].J.Xi an Univ.of Arch.&Tech.(Natural Science Edition),1996,28(4):405-409.
[13]蒋建平.水下大直径超长桩理论分析与工程应用[D].南京:南京大学,2002.JIANGJian-ping.The theory analysis and engineering application for large diameter and super-long bored-cast-place piles under water[D].Nanjing:Nanjing University,2002.
[14]蒋建平,高广运.大直径超长桩有效桩长的数值模拟[J].建筑科学,2003,19(3):27-29.JIANGJian-ping,GAO Guang-yun.The FEMnumerical si mulation on effective length of large diameter and su-per-long piles[J].Building Science,2003,19(3):27-29.
[15]蒋建平,章杨松,高广运,等.大直径超长灌注桩弹塑性有限元分析[J].力学季刊,2006,(2):45-49.JIANGJian-ping,ZHANG Yang-song,GAO Guang-yun,et al.The elasto-plastic FEMnumerical si mulation onlarge diameter and super-long bored-cast-place piles[J].Mechanics Quarterly,2006,(2):45-49.
[16]蒋建平,汪明武,高广运.桩端岩土差异对超长桩影响的对比研究[J].岩石力学与工程学报,2004,23(18):3190-3195.JIANGJian-ping,WANG Ming-wu,GAO Guang-yun.Contrastive study on influence of difference of pile endrock-soil layer on large diameter and super-long piles[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(18):3190-3195.
[17]龚维明,戴国亮,薛国亚,等.东海大桥超长钻孔灌注桩自平衡试验研究[J].岩土工程界,2004,7(2):40-43.GONG Wei-ming,DAI Guo-liang,XUE Guo-ya,et al.Experi mental study on super-long bored-cast-place piles inDonghai large bridge engineering[J].Geotechnical Engineering World,2004,7(2):40-43.
[18]黄生根,龚维明.苏通长江大桥北引桥二期试桩试验研究[J].工程地质学报,2005,13(1):107-111.HUANG Sheng-gen,GONG Wei-ming.Testing piles for the second state of north bridge approach of Sutong Yan-gtze River[J].Journal of Engineering Geology,2005,13(1):107-111.
[19]王志辉,刘斌,庄平辉.大直径桩端压力注浆桩的承载性状试验[J].东北大学学报:自然科学版,2002,23(2):160-163.WANHZhi-hui,LI U Bin,ZHUANG Ping-hui.Bearing behavior experi mental of bottom-grouting large diameterpore pile[J].Journal of Northeastern University(Natural Science Edition),2002,23(2):160-163.
[20]刘之春,蒋永生,龚维明.大直径扩底桩承载力的沉降变形控制设计法初探[J].东南大学学报:自然科学版,2001,31(4):49-53.LIUZhi-chun,JIANG Yong-sheng,GONG Wei-ming.Study on design method of settlement controllingfor bearing capacityof large diameter belled piles[J].Journal of Southeastern University(Natural Science Edition),2001,31(4):49-53.
[21]张聚山,王俊林.扩底墩基础设计与分析[J].岩土工程学报,1996,18(3):67-73.ZHANG Ju-shan,WANG Jun-lin.The design and analysis of belled piers foundation[J].Chinese Journal ofGeotechnical Engineering,1996,18(3):67-73.
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