Analysis Of The Pile Foundation Vertical Bearing Characteristic In Salt Marsh Area And Research On Its Anticorrosive Technology

Salt marsh refers to such areas with over-wet surface, seasonal water, soil salinization and halophytes. The surface of salt marsh is alkaline with higher salt content in soil and the accumulated soluble salt on its surface. The salt that contained in the soil or water of the salt marsh area have both chemical and physical function to concrete, which makes the bridge pile foundation appear such corrosion damage phenomena as concrete corrosion and spallation, etc. The occurrence of such corrosion damages will affect the normal bearing capacity of the bridge and easily induce engineering diseases.According to the Highway Bridge Design General Specification(JTGD60-2004), the design reference period of highway bridge-culvert structure is 100 years. However, influenced by engineering service environment, it is very difficult for the service time of the highway bridge structures in salt marsh area to meet the design requirements.In this paper, based on the bridge project of Qinghai Dexiang Highway salt marsh area, the research was carried out aimed at the corrosion problems caused by composite salt of salt marsh area to the bridge foundation. The main research work is as follows:(1) The climate characteristics, topographical features, surface hydrological and hydrogeological conditions of the salt marsh area along the project were investigated and analyzed; and the rock mass and water types that induced the bridge pile foundation corrosion in the salt marsh area were proposed. Furthermore, by investigating some related bridge structures that have damaged by corrosion in similar engineering environment, this paper provided reference for the numerical simulation calculation condition design.(2) The mechanism of salt corrosion’s occurrence and effect was analyzed by laboratory test; following the single salt type and ion concentration that contained in the soil and water of engineering field, we prepared the corrosion solution, carried out the corrosion test and analyzed the test results.(3) Based on limited meta-simulation method to build the model for the bridge pile foundation before and after the corrosion, and in a changing situation of related salt corroding the pile body’s flaking thickness and corrosion depth, the characteristics and change rules of the vertical bearing capacity of bridge pile foundation were also analyzed.(4) From the isolation resistance, crack resistance, dense and reinforcing steel rust and other technical aspects, we put forward the corrosion prevention and control measures, elaborated the anti-corrosion mechanism of each anti-corrosion technology, and finally the key technology methods of anti-corrosion were put forward.