Application Of Acoustic Reflection And Transmission Technique On Integrity Assessment For Piles

Pile foundation is the most widely used form of basis, With the healthy and harmonious development of national economy, the investment in the area of state transportation infrastructure increase year by year. A large number of highways, provincial roads, channels and a variety of municipal construction projects to invest in construction. Pile Foundation meets the design requirements directly related to the bridge structure and people's lives and property. However, due to the high pile of hidden construction, construction quality is difficult to control, influence the quality of Pile Foundation Construction influenced by many factors, therefore, a reasonable selection of pile testing methods for ensuring the quality of the project is of great significance.In this paper the actual engineering projects, for engineering drilling, filling pile of quality testing, the use of acoustic wave reflection method and transmission method for testing the integrity of the pile, trying to be their application in all its aspects summarized, so that inspectors a more specific understanding, and promote the proper application of the method is reasonable and healthy development of the main contents of this paper is as follows:The first chapter introduces the importance of pile integrity testing. The integrity of the pile and the material strength and other quality issues directly affect the stability of the entire upper structure, if the pile there is no timely identify quality problems and take remedial measures, the whole project will be irreparable loss, the people pose a threat to life and property. Especially given the team quite a mixed bag of pile foundation construction, construction technology range, good buckwheat missing construction machinery, pile foundation construction quality is very unstable, resulting in a lot of security risks. Defects in the pile of concrete and construction methods are closely related. Defects of different types of construction methods and the emergence of different types of defects are not as likely to occur. Infusion and water infusion of underwater concrete piles were prone to defects in detail, widely used in engineering, pile testing technology was introduced.The second chapter describes the low-strain reflected ultrasonic wave method and pile integrity testing for the basic principles. For low strain reflected wave method in time domain and frequency domain analysis theory described in detail, with specifications, reflected wave on the low strain detection instruments and equipment, field testing techniques and data analysis and processing is described in detail. For the ultrasonic testing of pile integrity, its acoustic principles described in detail, with specifications. The method of detection equipment, scope, field test technologies and test data analysis and processing is described in detail. For the subsequent chapters provide a solid theoretical foundation.Chapter III will combine theory and engineering practice, detailing the necking, expanding, segregation, and other defective piles pile typical time-domain curve. For segregation piles, piles and other bottom sediment is more difficult to determine the shaft defects, in view of these piles is currently no definite wave curve, is relatively difficult to judge, with coring of this chapter, for such time-domain analysis of pile put forward some suggestions. On the one hand demonstrate the basic theory of reflection wave method, on the other hand also provide guidance on future testing. Frequency domain analysis to test the vibration analysis of an important part. Frequency domain analysis can be used to guide the sensor installation, remove all noise disturbances frequency domain analysis to make up for lack of time. Engineering practice in this chapter, on the complete defect pile piles and frequency domain analysis of the simple set, proved that the method can determine the length of pile construction and defect location, but can not determine the type of defect. Therefore, the actual project should be considered in the time domain and frequency domain analysis of the results, draw conclusions to determine the most ideal.Chapter IV on the basis of the acoustics, the sound wave transmission technology in pile integrity testing, on the practical application has a guiding value. Acoustic reflection method to each point on the pile of sound, the sound velocity, amplitude and so the data reflect real-time, through the acoustic pipe laying, to overcome the low-strain pile length emission wave method limited by the defects.For a complete pile, its velocity, amplitude, time curves of the sound is less than the critical value; for necking pile should be understood on the basis of geological data, tends to reduce the speed of sound, sound a longer time; for segregation pile, velocity, amplitude, PSD curve are often abnormal. Ultrasonic testing should be considered for various factors, to avoid miscarriage of justice.Chapter V of this paper, a detailed summary of the content, and future research directions are put forward.