Fundamental Research On High-strain Dynamic Pile Testing Method Based On Measured Curve Fitting Method

The construction quality of pile foundations is one of the important guarantees for the quality of the buildings,and the guarantee of piles’ bearing capacity is linked to the safety of people’s lives and property.In order to ensure the safety and reliability of pile foundations,the inspection of body integrity and bearing capacity of piles is an important step after construction.The high-strain dynamic pile testing method is a commonly used quality inspection method currently.However,the analysis method has a certain degree of experience,and the commonly used equipment and software originate from foreign countries.The independent realization based on a more scientific pile-soil interaction model is an urgent need.This thesis targets at the realization of an edited bearing capacity analysis method based on existing testing archives,and realized a visual application program,which provides a reference for the development and application of the high-strain dynamic pile testing method.The main contents are as follows:1)Establishment of traditional simulation algorithms.Through the discussion of waveform fitting method,the pile-soil dynamic model is established and the corresponding simulation algorithm is realized using wave theory.Through the calculation of several cases,its certain correctness is verified.2)Introduction of improved measures for high-strain dynamic pile testing method.This thesis introduces a softening model for pile shaft that can consider the initial ultimate shear stress and the stress softening process,a segmented hyperbolic model for pile end that can simulate the segmented performance of the bearing capacity,a soil plug model that can simulate the possible embedded soil at the bottom of the pile and the body material damping model that can simulate the vibration of the pile.At the same time,a single pile settlement simulation method based on dichotomy is introduced.The relationship curve between loads and settlements on pile top can be obtained through iteration.The sensitivity of the parameters in the improved algorithm to the calculated curve is analyzed.Then verification of the applicability and reliability of the improved analysis method through actual examples was done.The results show that the model parameters obtained by the improved analysis method can simulate the bearing performance of soil well,and the analysis results are in line with the actual situation and are reliable.3)Realization of a visualized desktop application based on the algorithm introduced in this thesis.The application is developed using the object-oriented programming language C#and WPF framework based on the modular programming concept,having rich visual input and output,strong reliability and ease of use.