The Response Characteristics Of The Reflected Wave On Abnormal Piles And The Application Research Of Simulation

With the scale of construction expanding and the ground treatment depth increasing,the pile foundation is used in engineering more and more widely.The integrity of pile is associated with the safety of engineering.Defective piles is easy to affect the bearing capacity of pile foundation caused by engineering the loss of human,material and financial resources,so how to detect the integrity of pile in the engineering is an indispensable key link.The complexity of engineering environment and different types of the defective piles bring certain difficulty for pile integrity testing.If you don't study the response characteristics of defective piles,it is easy to cause confusion so that could not do some special prevention and governance.Combined with practical engineering problems,the article does some research about low strain reflection wave method by using the measures of the numerical simulation and field test.Combining with the current situation of low strain reflected wave method,this paper expounds the one-dimensional wave theory and presents the Dalan Bell solution,showing that the basic characteristic of the longitudinal wave in the pile foundation.According to the reflection coefficient of stress wave and displacement wave at the same time,it laid the deep theory foundation for the analysis of the reflection curve of pile.Using ABAQUS numerical software of different specifications and the integrity of the pile,pile with single defects,a numerical simulation of the pile with composite defects are discussed from the point of view of time domain of concrete strength,impact load,slenderness ratio and the influence of soil factors on the integrity of pile,at the same time the broken pile,segregation,reducing piles,pile and composite defects of hole diameter,the basic characteristics such as amplitude,phase contrast and analysis of the response curves of all kinds of pile low strain reflected wave characteristics.To test and verify the abnormal response characteristics of pile and the accuracy of the low strain reflected wave method,5 test piles and 5 engineering piles were tested at the scene by the pile strain gauge.Then,the characteristics of the reflected wave of the piles are analyzed,and their integrity are evaluated from two angles of time domain and frequency domain,providing a reference for engineering site inspection application.Studies have shown that low strain reflected wave method in pile integrity testing has obvious advantages,suitable for different types of pile testing,but there are still some problems in testing technology needs further research.