Study On Evaluation And Prediction Of The Grey System Theory In Ultrasonic Testing Of Pile Foundation

During the engineering construction process, the pile foundation project contains many uncertain factors that might give rise to quality problems, thus in order to ensure the smooth progress of the engineering project, study on methods to test quality of the pile foundation project has become priority among priorities. There are lots of methods to test the pile foundation, such as low strain detection, core drilling method, high strain detection, ultrasonic testing and so on, each of which has its own characteristics, but all of them have one common drawback, that is, they all evaluate quality of the pile body with single acoustic parameters, which is definitely not scientific enough. At present, ultrasonic testing is extensively used for its features, e.g. wide detection range, relatively stable data, insusceptible to the influence of length-diameter ratio etc., but it also has some limits, for it is not able to have a comprehensive consideration of all the acoustic parameters, its detection process is tedious, which wastes manpower. According to needs of the pile foundation detection during practical projects, the paper conducts an in-depth study on evaluation of ultrasonic testing and prediction of integrity of the concrete of the pile foundation, and analyzes quality of the pile foundation with the Grey System Theory and the ultrasonic testing method combined.The paper aims to have a scientific evaluation of the pile body's integrity using data obtained by ultrasonic testing in practical construction project and the Grey Clustering Evaluation Method of the Grey System Theory, so as to avoid evaluation of the obscure pile relying on human experience. Meanwhile, the GM (1,1) Model in the Grey System Theory is adopted to carry out an effective prediction of quality of the pile body so as to avoid wasting unnecessary manpower and material resources, thereby save resources for construction units.The general method of ultrasonic testing to detect quality of concretes inside the pile body, the method to evaluate the integrity of the pile body and the method to detect the pile's defects are explained in this paper. Besides, it is also concluded by the paper that the accuracy of the current method which uses a single index, acoustic parameters, to evaluate integrity of the pile body, meets with much skepticism, besides, manpower and material resources can be easily wasted with this method used, therefore, a more scientific and effective method should be found to ensure the accuracy of the test results and avoid wasting of resources. At the same time, the Grey System Theory, Grey Prediction and Grey Evaluation are also studied in the paper, the timeliness of the Grey System Theory in solving different problems in different fields is concluded, and therefore the relationship between test data gained by ultrasonic testing and the Grey System Theory can be boldly studied. As indicated by the study, the Grey System Theory is able to accurately express integrity of the pile body according to test data gained by ultrasonic testing. Hence, corresponding mathematical methods are applied to prove this and then the paper comes up with some suggestions.In order to verify the feasibility of the Grey System Theory in evaluate integrity of the pile body with ultrasonic testing, data gained in practical construction projects are taken as the basis, the Grey Clustering Evaluation Method and establishes the Grey Clustering Model is emphatically introduced and the Grey Clustering Model is established. It has been proved by a large number of project cases, that the Grey Clustering Method is able to synthesize various influencing factors, accurately evaluate the assessment results of ultrasonic testing and very authentically reflect the pile foundation's quality, and compared with other evaluation methods, this method is proved to be more scientific; meanwhile, with the GM (1,1) Model in the Grey System Theory introduced, the scientific results gained by the Grey Clustering Evaluation Method as the basis, the GM (1,1) Model established using the actual test data and the predicted results compared with the actual test results, the paper verifies that the GM (1,1) Model is applicable in ultrasonic testing of the pile foundation and only a few data will be needed to effectively predict integrity of the pile body's quality. With such a method, manpower and material resources can be effectively saved.