A Study On Reliability Method For Damage Identification Of Solid Concrete Piles Based On Low-strain Reflected Wave Method

As one of common methods for pile integrity testing,low-strain reflected wave method,on which fruitful accomplishments have been achieved in the fields of the theoretical analysis and the test system after nearly hundred years of development,has been extensively applied to the construction of municipal enginerring and highway or water transport project.However,in the traditional method,the massive assumptions are taken into account ignoring the pile-soil interaction,the damp of pile shaft material and the transverse inertia effect,making it difficult for quantitative analysis of pile defect in practical engineering.Due to the combined effects of the testing noise,and the variabilities including structural parameters,and vibrating parameters,and geologic parameters,the test results of the pile defect in low-strain reflected wave method are so uncertain that it may lead to misjudgment of the classification of pile integrity.The main innovative work in this dissertation is that both certainty analysis and reliability analysis are proposed for the damage identification of solid concrete piles.The study on the low-strain reflected wave method-based solid concrete piles damage indentification reliability methods is developed on the basis of structural reliability theory and principle of both damage identification dynamic fingerprint methods and low-strain reflected wave method.The following research results are achieved in this dissertation:(1)The development of piles is briefly stated,and the basic principle and main test system of low-strain reflected wave method are introduced.The development and application of the probability analysis of structural damage identification are summarized systematically in this paper.(2)The vibration property of the low-strain reflected wave method is introduced,including the pulse function,the pulse width and the amplitude of exciting force.The development and application of one-dimensional elastic straight rod traveling wave method based on D'Alembert solution and finite element method are summarized systematically in this paper,and their advantages and disadvantages are also pointed out.On the foundation of soil constitutive model with plain strain,the one-dimensional motion equation is established for time-domain solutions,considering the combined vibration of pile-soil interaction,the material damping and the transverse inertia effect of pile.In addition,to investigate the feasibility and effectiveness of the analytical method with pile-soil interaction,numerical examples in different codes have been analyzed.(3)The development of the damage identification of solid concrete piles is briefly stated.The low-strain dynamic signature method is proposed in this paper for pile damage identification by combining low-strain reflected wave method and analytical method with pile-soil interaction.In addition,to investigate the feasibility and effectiveness of the present method for pile damage identification,an indoor test of pile model with defect and numerical examples in different codes have been completed.(4)Based on the structural reliability theory,the reliability method of pile damage identification is presented in combination with response surface Monte-Carlo simulation method and the low-strain reflected wave dynamic signature method.In this method,both the reliability problem with given accuracy and the precision problem with given reliability of pile damage identification can be solved.In addition,according to the traditional classification of pile integrity,the probability analysis method of pile integrity classification and the pile integrity classification method in the sense of probability are proposed,the feasibility and effectiveness of which are validated by numerical examples and practical projects.The major innovative points of this study are as follows:(1)On the foundation of soil constitutive model with plain strain,the one-dimensional motion equation is established for time-domain solutions,considering the combined vibration of pile-soil interaction,the material damping and the transverse inertia effect of pile.(2)The low-strain dynamic signature method is proposed in this paper for pile damage identification by combining low-strain reflected wave method and analytical method with pile-soil interaction.(3)Based on the structural reliability theory,the reliability method of pile damage identification is presented in combination with response surface Monte-Carlo simulation method and the low-strain reflected wave dynamic signature method.In addition,according to the traditional classification of pile integrity,the probability analysis method of pile integrity classification and the pile integrity classification method in the sense of probability are proposed.