Research On Detection And Damage Assessment Of Underwater Pile Foundation

Pile foundations are the main form of bridge foundations,and timely repair of the diseases of underwater pile foundations can avoid many bridge collapse accidents.However,due to technical difficulties and late start-up development,there are many problems to be solved in the disease detection and damage assessment of underwater pile foundations.For this reason,this article has carried out research on underwater pile foundation disease detection and damage assessment.The research methods of this paper include field testing,numerical simulation calculation and mathematical modeling analysis;the main research contents and conclusions are as follows:(1)The disease detection of the Jiangwan Bridge in Jilin city was carried out.This paper compares the current mainstream underwater pile detection methods by consulting data and analyzes their respective advantages and disadvantages.After comprehensively considering the objective conditions of the site and economic factors,the method of underwater exploration and underwater photography is selected for Jilin City.The Jiangwan Bridge has been inspected for underwater pile foundation diseases.Through field testing,it is found that the underwater pile foundation damage of the Jiangwan Bridge in Jilin City is relatively minor.Typical diseases that appear are the spalling of concrete on the surface of the underwater pile foundation and the erosion and hollowing of the bottom of the pile foundation.(2)The pile foundation bearing capacity analysis under the influence of typical diseases is carried out.Because the damage information obtained by the disease detection cannot directly calculate the loss of the bearing capacity of the damaged pile foundation,in order to make the result of the disease detection intuitively and accurately reflect the decrease in the bearing capacity of the damaged pile foundation,this paper has carried out the typical disease on the bearing capacity of the pile foundation.Quantitative analysis of impact.The study was carried out by way of numerical simulation,quantitatively analyzed the bearing capacity changes of pile foundations with different pile lengths and pile diameters when they were affected by different diseases of different severity.(3)Quantitative analysis found that the size of the pile foundation has a significant impact on the loss of the bearing capacity of the pile foundation when the disease occurs,and the severity of the disease has a significant impact on the decline rate of the bearing capacity of the pile foundation when the disease occurs.The load-bearing capacity drops faster.Therefore,minor early and mid-term diseases should not be ignored in the later maintenance of bridge pile foundations,so as to avoid the rapid decline of pile foundation bearing capacity due to the deterioration of the diseases.(4)Established an underwater pile foundation damage assessment model.Since the numerical simulation results cannot completely achieve the goal of directly calculating the loss of the bearing capacity of the damaged pile foundation through the damage information obtained by the disease detection(can only be achieved under the preset working conditions),this paper uses mathematical modeling methods to carry out the numerical simulation results Fitting,an underwater pile foundation damage assessment model with the severity of the disease and the size of the pile foundation as variables is obtained,and the prediction accuracy of the model is verified by a variety of methods.(5)The practical application value of the model is analyzed.The analysis found that the damage assessment model established is not very versatile,therefore,the main value of the model does not lie in the model itself,but in the proposed new damage assessment method.The actual damage assessment can use the method proposed in this paper for reference,that is,use actual engineering information for numerical simulation calculation,and then establish a damage assessment model based on the results of the numerical simulation calculation for actual damage assessment.