散体材料桩复合地基桩土应力比计算方法研究
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摘要
基于圆孔扩张理论,假定散体材料桩与桩周土均满足完全弹性、各向同性和连续性条件,在侧向桩与土的分界面上满足变形协调条件和应力平衡方程,在竖向视桩-土变形相等,得到了桩土应力比的理论计算公式。引入了桩-土弹性模量比Kn及桩竖向-侧向应力比n',分析了桩-土弹性模量比、置换率、桩泊松比及桩周土泊松比等4个参数对桩土应力比和桩竖向-侧向应力比的影响。研究结果表明:桩土应力比和桩竖向-侧向应力比随桩-土弹性模量比的增大而增大,随桩、土泊松比及置换率的增大而减小。并在此基础上,利用桩土应力比现场实测结果对理论计算结果进行了验证,数据表明两者吻合较好。
Based on the theory of cavity expansion,the granular pile and soil around pile were treated as a perfectly elastic,isotropic,homogeneous continuous medium,and were assumed to satisfy the compatibility conditions of deformation and stress balance equation in the lateral pile-soil interface,and their vertical deformation was assumed to be equal.The theoretical calculation formula of pile-soil stress ratio was obtained.The pile-soil modulus ratio Knand vertical-lateral stress ratio n' were introduced as two new parameters.Then the effects of 4 parameters,which are pile-soil elasticity modulus ratio,replacement rate,pile Poisson' s ratio and soil Poisson' s ratio,on pile-soil stress ratio and vertical-lateral stress ratio were investigated.The results show that:the pile-soil stress ratio increases with the increase of the elastic modulus ratio,while decreases with the increase of pile Poisson's ratio,soil Poisson's ratio and replacement ratio,and the vertical-lateral stress ratio follows the same rules.Moreover,it is proved that the theoretical results agree with the measured data well by a field test.
Based on the theory of cavity expansion,the granular pile and soil around pile were treated as a perfectly elastic,isotropic,homogeneous continuous medium,and were assumed to satisfy the compatibility conditions of deformation and stress balance equation in the lateral pile-soil interface,and their vertical deformation was assumed to be equal.The theoretical calculation formula of pile-soil stress ratio was obtained.The pile-soil modulus ratio Knand vertical-lateral stress ratio n' were introduced as two new parameters.Then the effects of 4 parameters,which are pile-soil elasticity modulus ratio,replacement rate,pile Poisson' s ratio and soil Poisson' s ratio,on pile-soil stress ratio and vertical-lateral stress ratio were investigated.The results show that:the pile-soil stress ratio increases with the increase of the elastic modulus ratio,while decreases with the increase of pile Poisson's ratio,soil Poisson's ratio and replacement ratio,and the vertical-lateral stress ratio follows the same rules.Moreover,it is proved that the theoretical results agree with the measured data well by a field test.
引文
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[14]赵明,赵明华,陈昌富.确定碎石桩复合地基桩土应力比的一种新方法[J].湖南大学学报:自然科学版,2002,29(2):112-116.ZHAO M,ZHAO M H,CHEN C F.New pile-soil stress ratio calculation method in gravel-pile composite foundation[J].Journal of Hunan University:Natural Sciences,2002,29(2):112-116.
[2]龚文惠.碎石桩复合地基中桩土应力比的试验研究[J].土工基础,2002,14(4):57-60.GONG W H.Testing Study on Pile-Soil Stress Ratio in Crushed-stone-pile Composite Foundation[J].Soil Eng.and Foundation,2002,14(4):57-60.
[3]张定.复合地基中桩体变形的模量与计算[J].岩土工程学报,1999,21(1):205-208.ZHANG D.Analysis and computation of the deformation modulus of the pile in the composite foundation[J].Chinese Journal of Geotechnical Engineering,1999,21(1):205-208.
[4]邢皓枫,龚晓南,杨晓军.碎石桩复合地基固结简化分析[J].岩土工程学报,2005,27(5):521-524.XING H F,GONG X N,YANG X J.Simplified analysis for consolidation of gravel-pile composite foundation[J].Chinese Journal of Geotechnical Engineering,2005,27(5):521-524.
[5]Madbav M R.Recent developments in the use and analysis of granular piles[J].Symposium on Recent Developments in Ground Improvement Techniques,Bangkok,1982,1:605-609.
[6]王剑平,李景林,曹国兴,等.一个振冲碎石桩单桩承载力的经验公式[J].岩土工程学报,2002,24(4):496-498.WANG J P,LI J L,CAO G X,et al.An empirical formula for bearing capacity of vibro replacement stone column[J].Chinese Journal of Geotechnical Engineering,2002,24(4):496-498.
[7]Greenwood D A.Discussion on vibro flotation compaction in non-cohesive soils[J].Ground Treatment by Deep compaction,ICE,London,1976,23:17-45.
[8]韩杰,叶书麟,张德松.碎石桩复合地基应力及孔隙水压力的原位观测分析[J].岩土工程学报,1993,15(5):40-47.HAN J,YE S L,ZHANG D S.In-situ Observations on Backpressure and pore water pressures in composition foundation with stone columns[J].Chinese Journal of Geotechnical Engineering,1993,15(5):40-47.
[9]钱征.振冲法加固海底软土的试验研究[J].岩土工程学报,1988,10(4):49-56.QIAN Z.Vibroflotation Method in i mprovement of soft foundation at the sea bottom[J].Chinese Journal of Geotechnical Engineering,1988,10(4):49-56.
[10]黄茂松,陈云敏,吴世明.振冲碎石桩加固饱和粉砂粉土地基试验研究[J].岩土工程学报,1992,14(6):69-73.HUANG M S,CHEN Y M,WU S M.Strengthening of saturated silty soil by vibro replacement stone columns[J].Chinese Journal of Geotechnical Engineering,1992,14(6):69-73.
[11]马崇武,慕青松,马君伟,等.碎石桩单桩和多桩荷载传递方式的实验研究[J].岩石力学与工程学报,2008,27(S1):3 116-3 121.MA C W,MU Q S,MA J W,et al.Testing research on load transfer modes of single and multiple gravel piles[J].Chinese Journal of Rock Mechanics Engineering,2008,27(S1):3 116-3 121.
[12]赵明华,邓岳保,杨明辉.路堤荷载作用下碎石桩复合地基桩土应力比计算及试验研究[J].岩土力学,2009,30(9):2 623-2 628.ZHAO M H,DENG Y B,YANG M H.Calculation and model test for pile-soil stress ratio of gravel pile composite foundation under embankment load[J].Rock and Soil Mechanics,2009,30(9):2 623-2 628.
[13]刘杰,张可能.碎石桩复合地基应力应变分析[J].中南工业大学学报,2002,33(5):457-461.LIU J,ZHANG K N.Analysis of stress and strain on the composite foundation of gravel piles[J].J.CENT.South Univ.Technol,2002,33(5):457-461.
[14]赵明,赵明华,陈昌富.确定碎石桩复合地基桩土应力比的一种新方法[J].湖南大学学报:自然科学版,2002,29(2):112-116.ZHAO M,ZHAO M H,CHEN C F.New pile-soil stress ratio calculation method in gravel-pile composite foundation[J].Journal of Hunan University:Natural Sciences,2002,29(2):112-116.