Research On The Damage Identification Method Based On Dynamic Characteristics And Bearing Capacity Testing Technology Of High-piled Wharf Piles

High-piled wharf is one of the widely used harbor structure type, there are a lotof decades old high-piled wharfs in the field of port projects in China. These oldhigh-piled wharf piles were widespread damaged by ship impact loadings,environmental erosion and so on; meanwhile the detections of pile bearing capacityare the necessary preconditions of detection, evaluation and upgrading for the oldterminal. There are complex structures on the foundation piles, at this stage, for thesenon-free end piles, there are no effective and feasible damage diagnosis methods andbearing capacity detection methods. Therefore, how to identify the damages activehigh-piled wharf pile and honw to test the bearing capacity is an urgent need to studyand resolve.In this paper, theoretical analysis, numerical simulation, physical model tests andfield measurement methods were combined used to study damage diagnosis methodsbase on the dynamic characteristics, and bearing capacity detection methods of thehigh-piled wharf piles. Such scientific and technical issues were included: modalparameter identification method of the high-piled wharf under ambient excitation,damage identification and capacity detection methods of high-piled wharf piles.Firstly, research on the modal parameter identification methods of high-piledwharf under ambient excitation. Aimed at the difficult problem of exciting thehigh-piled wharf to dynamic test, the modal parameters identification methods ofhigh-piled wharf were studied based on ambient excitation load response in thenormal working hours.(1) ERA method is proposed to identify modal parameters ofhigh-piled wharf under ambient excitation. ERA algorithm is detailed derived, basedon the basic principles of the system minimal realization and natural incentivetechnologies, also the Next-ERA procedures for high-pile wharf modal identificationwere compiled.(2) The large scale high-piled wharf physical model (1:10) wasproducted considering pile-soil interaction, and the proposed theory of modalparameter identification method based on ambient excitation was applied to thephysical model testing, combined with the dynamic characteristics calculated bynumerical analysis, he high-piled wharf model modal order and dynamiccharacteristics by environmental load excitation were revealed. Secondly, research on damage diagnosis methods of the high-piled wharf piles.Aimed at characteristics of the high-piled wharf pile, the damage diagnostic methodsbased on modal strain energy was firstly proposed. Depending on the vibrationdifferential equations, the strain energy expression modal was derived in detail, andthe principle of strain energy damage localization was proved. The implementationsteps were given based on MSE and the procedures for damage diagnosis of thehigh-piled wharf piles were programmed. The damages of high-piled wharf piles indifferent conditions were diagnosed through a bent numerical analysis. The resultsalso demonstrated that modal strain energy as damage diagnosis parameter was verysensitive to damage element and could identify the high-piled wharf damages underdifferent operating conditions. The research results would provide a useful referencefor non-destructive dynamic testing based on the dynamic characteristics of high-pilewharf.Thirdly, the bearing capacity detection methods of high-piled wharf piles wereresearched. The regional heap load method to detect high-piled wharf piles capacitywas firstly proposed, also the load area, loading and unloading termination conditionsand other key technical issues were proposed and solved. The high-piled wharf pilescapacity prototype testing was firstly carried out, the deformation displacement ofwhile high-piled wharf, the displacement of piles, and the strain of structural elementswere tested under grading loads. Finally, the vertical bearing capacity of foundationpile was determined combined with numerical calculation. Based on the test results ofthe prototype test, the longitudinal beam and bored pile modification scheme wasproposed for the support project. The modification scheme can improve the overallvertical bearing capacity, while maintaining the structural integrity and deformationcompatibility.