旁孔透射波法确定桩底深度方法对比研究
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摘要
针对既有工程桩检测难题而提出的旁孔透射波法被认为最有应用前景的方法之一。现有关于旁孔透射波法的研究以桩顶裸露自由桩为对象尚难以考察其对既有工程桩的测试效果。现有旁孔透射波法确定桩底深度的3种方法,交点法、平移法、校正法,是否存在理论误差未知,加之在实际桩底深度确定方法的选择上没有具体原则,导致在结果可靠性评估上存在不确定性。笔者采用基于射线理论的桩-土简化理论模型分析了以上3种桩底深度确定方法的理论基础和分析误差,并通过旁孔透射波法现场试验对结果正确性进行了验证。通过有限元参数分析探讨了不同桩底深度确定方法的误差随激振点距地高度、测孔-桩侧距、桩土波速比的影响,得到了3种旁孔透射波法桩底深度确定方法的适用性及适用条件。研究结果对具体条件下选择合适的旁孔透射波法桩底深度确定方法有重要意义。
Parallel seismic( PS) test is a most promising method proposed to deal with the difficulties in pile testing of existing piles. The current research related to piles with assessable pile head condition cannot be used to evaluate the capability of PS test for existing piles. The current three for determination of pile tip depth,are intersection point,translation up-line,and correction value methods. However,that whether these three pile tip depth evaluation methods existing theoretical error is still unknown. And as there is no specific principle to choose a proper pile tip depth evaluation method in practice,the reliability of the result of pile tip depth is uncertain. In this study,theory basis of these three PS methods was established by a simplified pile-soil theoretical model based on Snell 's Law. The analytical error and its expressions were then given,which was further verified by a PS in situ test.Numerical simulation was further employed to explore the change rule of the error varying with excitation-to-ground distance,pile-to-borehole distance,and pile-to-soil ratio of the P wave velocity. Then,the feasibility and applicable scope of the current three methods for determination of pile tip depth were obtained,which is of great significance for choosing suitable pile tip depth determination method under certain condition.
Parallel seismic( PS) test is a most promising method proposed to deal with the difficulties in pile testing of existing piles. The current research related to piles with assessable pile head condition cannot be used to evaluate the capability of PS test for existing piles. The current three for determination of pile tip depth,are intersection point,translation up-line,and correction value methods. However,that whether these three pile tip depth evaluation methods existing theoretical error is still unknown. And as there is no specific principle to choose a proper pile tip depth evaluation method in practice,the reliability of the result of pile tip depth is uncertain. In this study,theory basis of these three PS methods was established by a simplified pile-soil theoretical model based on Snell 's Law. The analytical error and its expressions were then given,which was further verified by a PS in situ test.Numerical simulation was further employed to explore the change rule of the error varying with excitation-to-ground distance,pile-to-borehole distance,and pile-to-soil ratio of the P wave velocity. Then,the feasibility and applicable scope of the current three methods for determination of pile tip depth were obtained,which is of great significance for choosing suitable pile tip depth determination method under certain condition.
引文
[1]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.(Chen Longzhu,Zhao Rongxin.On determination of pile length with parallel seismic testing for existing structures[J].Chinese Journal of Underground Space and Engineering,2010,6(1):157-161.(in Chinese))
[2]贾强,张鑫,张琳.既有建筑桩基础开挖过程中承载特性数值分析[J].地下空间与工程学报,2016,12(1):114-118.(Jia Qiang,Zhang Xin,Zhang Lin.Numerical analysis on the bearing behavior of the existing building’s pile caused by excavation around piles[J].Chinese Journal of Underground Space and Engineering,2016,12(1):114-118.(in Chinese))
[3]张敬一,陈龙珠.基于小波变换的反射波法检测基桩[J].振动与冲击,2014,33(6):179-183.(Zhang Jingyi,Chen Longzhu.Sonic echo test for pile integrity testing based on wavelet transform[J].Journal of Vibration and shock,2014,33(6):179-183.(in Chinese))
[4]Gassman S L,Finno R J.Cutoff frequencies for impulse response tests of existing foundations[J].Journal of Performance of Constructed Facilities,2000,14(1):11-21.
[5]Olson L D,Liu M,Aouad M F.Borehole NDT techniques for unknown subsurface bridge foundation testing[A]∥Proceedings of SPIE,Nondestructive Evaluation of Bridges and Highways[C].1996:10-16.
[6]Liao S T,Tong J H,Chen C H,et al.Numerical simulation and experimental study of parallel seismic test for piles[J].International Journal of Solids and Structures,2006,43(7-8):2279-2298.
[7]黄大治,陈龙珠.旁孔透射波法检测水泥搅拌桩的三维有限元分析[J].上海交通大学学报,2007,41(6):960-964.(Huang Dazhi,Chen Longzhu.3D finite element analysis of parallel seismic method for integrity of cemented soil columns[J].Journal of Shanghai Jiaotong University,2007,41(6):960-964.(in Chinese))
[8]Ni S H,Huang Y H,Zhou X M,et al.Inclination correction of the parallel seismic test for pile length detection[J].Computers and Geotechnics,2011,38(2):127-132.
[9]Niederleithinger E.Improvement and extension of the parallel seismic method for foundation depth measurement[J].Soils and Foundations,2012,52(6):1093-1101.
[10]Lu Z T,Wang Z L,Liu D J.A study on the application of the parallel seismic method in pile testing[J].Soil Dynamics and Earthquake Engineering,2013,55:255-262.
[11]Zhang J Y,Chen L Z.Discussion of:A study on the application of the parallel seismic method in pile testing[J].Soil Dynamics and Earthquake Engineering,2014,67(12):370-371.
[12]张敬一,陈龙珠,宋春霞,等.旁孔透射波法与反射波法检测基桩的对比分析[J].哈尔滨工业大学学报,2013,45(8):99-104.(Zhang Jingyi,Chen Longzhu.Song Chunxia,et al.Comparison of parallel seismic and reflected wave tests for piles[J].Journal of Harbin Institute of Technology,2013,45(8):99-104.(in Chinese))
[2]贾强,张鑫,张琳.既有建筑桩基础开挖过程中承载特性数值分析[J].地下空间与工程学报,2016,12(1):114-118.(Jia Qiang,Zhang Xin,Zhang Lin.Numerical analysis on the bearing behavior of the existing building’s pile caused by excavation around piles[J].Chinese Journal of Underground Space and Engineering,2016,12(1):114-118.(in Chinese))
[3]张敬一,陈龙珠.基于小波变换的反射波法检测基桩[J].振动与冲击,2014,33(6):179-183.(Zhang Jingyi,Chen Longzhu.Sonic echo test for pile integrity testing based on wavelet transform[J].Journal of Vibration and shock,2014,33(6):179-183.(in Chinese))
[4]Gassman S L,Finno R J.Cutoff frequencies for impulse response tests of existing foundations[J].Journal of Performance of Constructed Facilities,2000,14(1):11-21.
[5]Olson L D,Liu M,Aouad M F.Borehole NDT techniques for unknown subsurface bridge foundation testing[A]∥Proceedings of SPIE,Nondestructive Evaluation of Bridges and Highways[C].1996:10-16.
[6]Liao S T,Tong J H,Chen C H,et al.Numerical simulation and experimental study of parallel seismic test for piles[J].International Journal of Solids and Structures,2006,43(7-8):2279-2298.
[7]黄大治,陈龙珠.旁孔透射波法检测水泥搅拌桩的三维有限元分析[J].上海交通大学学报,2007,41(6):960-964.(Huang Dazhi,Chen Longzhu.3D finite element analysis of parallel seismic method for integrity of cemented soil columns[J].Journal of Shanghai Jiaotong University,2007,41(6):960-964.(in Chinese))
[8]Ni S H,Huang Y H,Zhou X M,et al.Inclination correction of the parallel seismic test for pile length detection[J].Computers and Geotechnics,2011,38(2):127-132.
[9]Niederleithinger E.Improvement and extension of the parallel seismic method for foundation depth measurement[J].Soils and Foundations,2012,52(6):1093-1101.
[10]Lu Z T,Wang Z L,Liu D J.A study on the application of the parallel seismic method in pile testing[J].Soil Dynamics and Earthquake Engineering,2013,55:255-262.
[11]Zhang J Y,Chen L Z.Discussion of:A study on the application of the parallel seismic method in pile testing[J].Soil Dynamics and Earthquake Engineering,2014,67(12):370-371.
[12]张敬一,陈龙珠,宋春霞,等.旁孔透射波法与反射波法检测基桩的对比分析[J].哈尔滨工业大学学报,2013,45(8):99-104.(Zhang Jingyi,Chen Longzhu.Song Chunxia,et al.Comparison of parallel seismic and reflected wave tests for piles[J].Journal of Harbin Institute of Technology,2013,45(8):99-104.(in Chinese))
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