Experimental Study On Durability Of CFG Pile Material In Fulvic Acid Environment

CFG pile composite foundation has many advantages,which can be used to reinforce the peat soil.However,peat soil contains a lot of humus,which may cause corrosion damage to the CFG pile,and have an adverse impact on the mechanical properties and engineering properties of the CFG pile,thus affecting the bearing capacity of the CFG pile composite foundation,and even endangering the safety of the superstructure.Therefore,it is of great significance to study the corrosion degradation of CFG pile in peaty soil environment.This paper takes the material of CFG pile body as the research object,uses fulvic acid solution to simulate peat soil environment,studies the influence of the content of fly ash on the strength and corrosion resistance of the pile material through strength test and long-term indoor corrosion immersion test,and preliminarily reveals the interaction mechanism between the pile material and fulvic acid solution.The main research contents are as follows:(1)According to the change of compressive strength of pile material specimens in clear water with immersion time,the influence of the amount of fly ash on the early strength and the later strength growth of the pile material is studied.It is concluded that the 45% fly ash content is the most favorable for the later strength growth of pile material specimens in non-corrosive environment.A set of prediction model for the strength of pile material specimen in non-corrosive environment is proposed.(2)From the apparent change of pile material specimen immersed in fulvic acid solution for a long time,it can be seen directly that fulvic acid solution will cause obvious corrosion to pile material specimen.From the change of strength,it can be seen that fulvic acid solution can inhibit the later strength growth of pile materials,even lead to the later strength reduction.From the change trend of average acid consumption and average acid consumption rate,it can be seen that the corrosion of pile material specimen by fulvic acid solution can be divided into two stages: rapid corrosion and corrosion stability.(3)Taking the strength growth rate and anti-corrosion coefficient of pile material in fulvic acid solution as evaluation indexes,it is considered that adding appropriate amount of fly ash(35%～40% is suitable)is able to improve the anti-corrosion performance of pile material,to weaken the inhibition effect of fulvic acid solution on the strength growth of pile material.A set of strength prediction model for pile material specimen in fulvic acid corrosion environment is proposed.