旁孔透射波法与反射波法检测基桩的对比分析
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摘要
为了解决桩基检测中长桩桩底与深部缺陷难以识别的问题,采用旁孔透射波法,建立桩-土系统简化理论模型,对旁孔透射波法提出了桩身缺陷及桩底深度的检测分析方法,并采用三维轴对称有限元模型,对比分析了旁孔透射波法与低应变反射波法检测的技术效果.结果表明,反射波法适用于非长桩的长度和深度不大的桩身缺陷检测,虽然指数放大有助于辨识长桩底端和较深处桩身缺陷的反射信号,但在实际应用中仍会存在一定的不确定性.旁孔透射波法受桩长和长径比的影响显著小于反射波法,在桩身缺陷位置及其程度和桩底深度的检测分析中更具优势.
For solving the difficulties in evaluation of the pile tip embedded depth for a long pile and depth of a deep embedded defect,the parallel seismic test is proposed in this paper.A simplified theoretical model of pile-soil system is established to determinate embedded depths of the pile tip and defect.Three-dimensional(3-D) axisymmetric finite element models were established for comparison of the parallel seismic(PS) and the reflected wave(RW) tests for piles.It was found that the RW test was suitable for determination tip embedded depth of a non-long pile and a non-deep embedded defect of a pile.Exponential amplification could be employed to deal with such difficulties,but still there were uncertainties existing in practical application.Compared to RW test,PS test is much less affected by pile length and depth-to-diameter ratio,and has advantages in identifying the embedded depth and degree of a defect as well as the embedded depth of the pile tip.
For solving the difficulties in evaluation of the pile tip embedded depth for a long pile and depth of a deep embedded defect,the parallel seismic test is proposed in this paper.A simplified theoretical model of pile-soil system is established to determinate embedded depths of the pile tip and defect.Three-dimensional(3-D) axisymmetric finite element models were established for comparison of the parallel seismic(PS) and the reflected wave(RW) tests for piles.It was found that the RW test was suitable for determination tip embedded depth of a non-long pile and a non-deep embedded defect of a pile.Exponential amplification could be employed to deal with such difficulties,but still there were uncertainties existing in practical application.Compared to RW test,PS test is much less affected by pile length and depth-to-diameter ratio,and has advantages in identifying the embedded depth and degree of a defect as well as the embedded depth of the pile tip.
引文
[1]陈凡,徐天平,陈久照,等.基桩质量检测技术[M].北京:中国建筑工业出版社,2003:2-25.
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[7]LO K F,HUANG S H,ZHOU X M.Measurement ofunknown bridge foundation depth by parallel seismicmethod[J].Experimental Techniques,2009,33(1):23-27.
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[9]黄大治,陈龙珠.旁孔透射波法检测既有建筑物桩基的三维有限元分析[J].岩土力学,2008,29(6):1569-1574.
[10]吴宝杰,杨桦.联合平行地震法和磁法检测预应力混凝土长管桩的长度[J].工程质量,2009,27(1):27-29.
[11]LIAO S T,TONG J H,CHEN C H,et al.Numericalsimulation and experimental study of parallel seismic testfor piles[J].International Journal of Solids andStructures,2006,43(7/8):2279-2298.
[12]ZHANG Jingyi,CHEN Longzhu.Selection of piletesting signals for parallel seismic test[J].AdvancedMaterials Research,2012,368-373:2045-2049.
[13]KIM D S,KIM H W,KIM W C.Parametric study onthe impact-echo method using mock-up shafts[J].NDT&E International,2002,35:595-608.
[14]CHOW Y K,PHOON K K,CHOW W F.Low strainintergrity testing of pile:three-dimensional effect[J].Journal of Geotechnical and GeoenvironmentalEngineering,2003,129(11):1057-1062.
[15]陈龙珠,赵荣欣.旁孔透射波法确定桩底深度计算方法评价[J].地下空间与工程学报,2010,6(1):157-161.
[2]CHAI H Y,PHOON K K,ZHANG D J.Effects of thesource on wave propagation in pile integrity testing[J].Journal of Geotechnical and GeoenvironmentalEngineering,2010,136(9):1200-1208.
[3]LIAO S T,ROESSET J M.Identification of defects inpiles through dynamic testing[J].International Journalfor Numerical and Analytical Methods in Geomechanics,1997,21(4):277-291.
[4]KIM D S,KIM H W.Effects of surrounding soilstiffness and shaft length in the impact-echo test ofdrilled shaft[J].Journal of Civil Engineering,KSCE,2003,7(11):755-762.
[5]HUANG Y H,NI S H,LO K F,et al.Assessment ofidentifiable defect size in a drilled shaft using sonic echomethod:numerical simulation[J].Computers andGeotechnics,2010,37(6):757-768.
[6]GASSMAN S L,FINNO R J.Cutoff frequencies forimpulse response tests of existing foundations[J].Journal of Performance of Constructed Facilities,2000,14(1):11-21.
[7]LO K F,HUANG S H,ZHOU X M.Measurement ofunknown bridge foundation depth by parallel seismicmethod[J].Experimental Techniques,2009,33(1):23-27.
[8]KENAI S,BAHAR R.Evaluation and repair of Algiersnew airport building[J].Cement and ConcreteComposites,2003,25:633-641.
[9]黄大治,陈龙珠.旁孔透射波法检测既有建筑物桩基的三维有限元分析[J].岩土力学,2008,29(6):1569-1574.
[10]吴宝杰,杨桦.联合平行地震法和磁法检测预应力混凝土长管桩的长度[J].工程质量,2009,27(1):27-29.
[11]LIAO S T,TONG J H,CHEN C H,et al.Numericalsimulation and experimental study of parallel seismic testfor piles[J].International Journal of Solids andStructures,2006,43(7/8):2279-2298.
[12]ZHANG Jingyi,CHEN Longzhu.Selection of piletesting signals for parallel seismic test[J].AdvancedMaterials Research,2012,368-373:2045-2049.
[13]KIM D S,KIM H W,KIM W C.Parametric study onthe impact-echo method using mock-up shafts[J].NDT&E International,2002,35:595-608.
[14]CHOW Y K,PHOON K K,CHOW W F.Low strainintergrity testing of pile:three-dimensional effect[J].Journal of Geotechnical and GeoenvironmentalEngineering,2003,129(11):1057-1062.
[15]陈龙珠,赵荣欣.旁孔透射波法确定桩底深度计算方法评价[J].地下空间与工程学报,2010,6(1):157-161.
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