Construction Quality Testing And Comprehensive Assessment Of Pile Based On Reflected Wave Method

In the social context of vigorously developing the transport services andinfrastructure，bridge structure has been widely used in China. As an important part of thebridge structure，Pile foundation can be able to transfer the upper structure weight load tothe deeper soil or rock where is more stable and has higher carrying capacity.it caneffectively reduce the impact of uneven geological conditions to ensure the safe andcomfortable operations of the upper bridge superstructure. However, the quality of ourconstruction teams varies greatly in good and bad, not able to strong grasping on thetechnology of construction. Foundation pile prone to defects in the construction process,thus it is easy to effect the carrying capacity.Therefore, it is greatly practical meaningful todetect and assess the quality of construction.The acoustic reflection is a method of detecting the pile integrity based on stress wavereflection.The simple and easy method which has mature theoretical foundation has beenmost widely used at home and abroad. In this article, combining the project of Jilin to thegrass city highway construction project, the pile integrity evaluation method based on thereflection wave method carried out as follows:Firstly,it described establishing procedures and principles of one dimensional waveequation of the pile foundation;secondly, it discussed the transient vibration responsecharacteristics of friction piles and end bearing pile transient.thirdly, it elaborated defectdiagnosis principle of pile integrity testing based on the reflection wave method.first of all, based on one dimensional wave equation and the principle of integritytesting of the piles foundation,it introduced acquisition of the characteristic parameters ofthe wave velocity, pile length, frequency, etc in acoustic reflection time-domain curve.second, the simulation of the complete pile, segregation piles and cross-section changes piletypical piles domain curve with the ANSYS/LS-DYNA finite element analysis softwareprovides the basis for practical engineering applications. Finally, the analysis of encountered of the typical time-domain curve during the test combining with practicalengineering experience can provide a reference for the practical application of the method.Taking into account the determining method of the pile integrity categoriesprescribed in the specification is not clear enough, it proposed a comprehensive evaluationmethod for the quality of pile construction based on the Analytic Hierarchy. The methodtakes into account acquisition of the characteristic parameters of wave velocity, pile length,geological conditions, the level of important for t he bridge, pile defects,etc to evaluate thequality of construction for t he pile foundation.it effectively reduce the influence of humanfactors to provide a more objective and accurate judgment for the quality of construction ofthe pile. Finally, the proposed assessment method has been used for quality assessment ofthe pile construction in actual project and made a good practical effect.