负摩阻力作用下的单桩竖向承载性状
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摘要
对负摩阻力作用下的单桩承载性状、负摩阻力与工作荷载之间的关系进行理论分析,然后建立单桩有限元模型,研究负摩阻力作用下桩基的承载性能、桩基的刚度以及下曳沉降变化规律。研究结果表明:下曳沉降由2部分组成,一是桩顶没有荷载作用时纯粹由负摩阻力引起的桩顶沉降;二是负摩阻力作用下,桩顶荷载下移中性点位置,使得承受桩顶荷载的桩段缩短所引起的沉降。负摩阻力在中性点平面形成的一对平衡力相当于在单桩桩体上施加了预应力,提高桩体本身的轴向刚度。
The vertical bearing behaviors of single pile under negative skin friction and the work load were analyzed.A finite element model of a single pile was set up to study the vertical bearing behavior,the pile stiffness and downdrag.The results indicate that the downdrag includes two parts: the first part is that the settlement of pile head induced only by negative skin friction and another part is the settlement of pile head caused by the work load which has moved down to the neutral plane when negative skin friction is hanging on the pile.The force equilibrium on the neutral plane acts like a prestressed force on pile which increases the pile stiff accordingly.
The vertical bearing behaviors of single pile under negative skin friction and the work load were analyzed.A finite element model of a single pile was set up to study the vertical bearing behavior,the pile stiffness and downdrag.The results indicate that the downdrag includes two parts: the first part is that the settlement of pile head induced only by negative skin friction and another part is the settlement of pile head caused by the work load which has moved down to the neutral plane when negative skin friction is hanging on the pile.The force equilibrium on the neutral plane acts like a prestressed force on pile which increases the pile stiff accordingly.
引文
[1]Fellenius B H.Unified design of piled foundations with emphasis on settlement analysis[C]//Geo-Institute Geo-TRANS Conference on Current Practice and Future Trends in Deep Foundations.Los Angeles:ASCE Geotechnical Special Publication,2004:253-275.
[2]Bjerrum L,Johannessen I J.Measurements of the compression of a steel pile to rock due to settlement of the surrounding clay[C]//Proceedings of the6th International Conference on Soil Mechanics and Foundation Engineering.Toronto:University of Toronto Press,1965:261-264.
[3]Bjerrum L,Johannessen I J,Eide O.Reduction of negative skin friction on steel piles to rock[C]//Proceedings of the7th International Conference on Soil Mechanics and Foundation Engineering.Mexico:Mexico Geotechnical Society,1969:27-34.
[4]Endo M,Minou A,Kawasaki T,et al.Negative skin friction acting on steel piles in clay[C]//Proceedings of the8th International Conference on Soil Mechanics and Foundation Engineering.Mexico:Mexico Geotechnical Society,1969:85-92.
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[6]王波,王保田,张福海,等.膨胀土地基桥台桩基负摩阻力现场试验研究[J].河海大学学报:自然科学版,2006,34(4):447-450.WANG Bo,WANG Baotian,ZHANG Fuhai.Field experimental study on negative friction along abutment pile in expansive soil ground[J].Journal of Hohai University:National Science,2006,34(4):447-450.
[7]徐兵,曹国福.部分桩身在回填土中的钻孔灌注桩负摩阻力试验研究[J].岩土工程学报,2006,28(1):56-58.XU Bing,CAO Guofu.Study on negative friction of bored piles in backfilled clay[J].Chinese Journal of Geotechnical Engineering,2006,28(1):56-58.
[8]黄雪峰,陈正汉,哈双,等.大厚度自重湿陷性黄土中灌注桩承载性状与负摩阻力的试验研究[J].岩土工程学报,2007,29(3):338-346.HUANG Xuefeng,CHEN Zhenghan,HA Suang,et al.Research on bearing behaviors and negative friction force for filling piles in the site of collapsible loess with big thickness[J].Chinese Journal of Geotechnical Engineering,2007,29(3):338-346.
[9]李玲玲,王立忠,刑月光.大直径钻孔灌注桩负摩阻力试验研究[J].岩石力学与工程学报,2009,28(3):583-890.LI Lingling,WANG Lizhong,XING Yueguang.Experimental research on negative skin friction of large-diameter bored piles[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(3):583-890.
[10]王兰民,孙军杰,黄雪峰,等.黄土场地震陷时桩基负摩阻力的现场试验研究[J].岩土工程学报,2008,30(3):341-348.WANG Lanmin,SUN Junjie,HUANG Xuefeng,et al.Field tests on negative skin friction along piles caused by seismic settlement of loess[J].Chinese Journal of Geotechnical Engineering,2008,30(3):341-348.
[11]夏力农,柳红霞,欧名贤.垂直受荷桩负摩阻力时间效应的试验研究[J].岩石力学与工程学报,2009,28(6):1177-1182.XIA Linong,LIU Hongxia,OU Mingxian.Experimental research on time effects of negative skin friction behaviors of vertical-loaded piles[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1177-1182.
[12]聂如松,冷伍明,杨奇,等.桩-土间剪切应力的传递探讨[J].岩土力学,2009,30(3):799-804.NIE Rusong,LENG Wuming,YANG Qi,et al.Discusion of the shear stress between pile and soil[J].Rock and Soil Mechanics,2009,30(3):799-804.
[13]JGJ94—2008建筑桩基技术规范[S].JGJ94—2008.Technical code for building pile foundations[S].
[2]Bjerrum L,Johannessen I J.Measurements of the compression of a steel pile to rock due to settlement of the surrounding clay[C]//Proceedings of the6th International Conference on Soil Mechanics and Foundation Engineering.Toronto:University of Toronto Press,1965:261-264.
[3]Bjerrum L,Johannessen I J,Eide O.Reduction of negative skin friction on steel piles to rock[C]//Proceedings of the7th International Conference on Soil Mechanics and Foundation Engineering.Mexico:Mexico Geotechnical Society,1969:27-34.
[4]Endo M,Minou A,Kawasaki T,et al.Negative skin friction acting on steel piles in clay[C]//Proceedings of the8th International Conference on Soil Mechanics and Foundation Engineering.Mexico:Mexico Geotechnical Society,1969:85-92.
[5]聂如松,冷伍明.软土地基桥台桩基负摩擦力的试验研究[J].铁道建筑,2005(6):1-4.NIE Rusong,LENG Wuming.Field test of negative skin friction on bridge abutment pile foundation in soft ground[J].Railway Engineering,2005(6):1-4.
[6]王波,王保田,张福海,等.膨胀土地基桥台桩基负摩阻力现场试验研究[J].河海大学学报:自然科学版,2006,34(4):447-450.WANG Bo,WANG Baotian,ZHANG Fuhai.Field experimental study on negative friction along abutment pile in expansive soil ground[J].Journal of Hohai University:National Science,2006,34(4):447-450.
[7]徐兵,曹国福.部分桩身在回填土中的钻孔灌注桩负摩阻力试验研究[J].岩土工程学报,2006,28(1):56-58.XU Bing,CAO Guofu.Study on negative friction of bored piles in backfilled clay[J].Chinese Journal of Geotechnical Engineering,2006,28(1):56-58.
[8]黄雪峰,陈正汉,哈双,等.大厚度自重湿陷性黄土中灌注桩承载性状与负摩阻力的试验研究[J].岩土工程学报,2007,29(3):338-346.HUANG Xuefeng,CHEN Zhenghan,HA Suang,et al.Research on bearing behaviors and negative friction force for filling piles in the site of collapsible loess with big thickness[J].Chinese Journal of Geotechnical Engineering,2007,29(3):338-346.
[9]李玲玲,王立忠,刑月光.大直径钻孔灌注桩负摩阻力试验研究[J].岩石力学与工程学报,2009,28(3):583-890.LI Lingling,WANG Lizhong,XING Yueguang.Experimental research on negative skin friction of large-diameter bored piles[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(3):583-890.
[10]王兰民,孙军杰,黄雪峰,等.黄土场地震陷时桩基负摩阻力的现场试验研究[J].岩土工程学报,2008,30(3):341-348.WANG Lanmin,SUN Junjie,HUANG Xuefeng,et al.Field tests on negative skin friction along piles caused by seismic settlement of loess[J].Chinese Journal of Geotechnical Engineering,2008,30(3):341-348.
[11]夏力农,柳红霞,欧名贤.垂直受荷桩负摩阻力时间效应的试验研究[J].岩石力学与工程学报,2009,28(6):1177-1182.XIA Linong,LIU Hongxia,OU Mingxian.Experimental research on time effects of negative skin friction behaviors of vertical-loaded piles[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(6):1177-1182.
[12]聂如松,冷伍明,杨奇,等.桩-土间剪切应力的传递探讨[J].岩土力学,2009,30(3):799-804.NIE Rusong,LENG Wuming,YANG Qi,et al.Discusion of the shear stress between pile and soil[J].Rock and Soil Mechanics,2009,30(3):799-804.
[13]JGJ94—2008建筑桩基技术规范[S].JGJ94—2008.Technical code for building pile foundations[S].
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