Study On Uniaxial Compression Damage Model And Failure Mechanism Of Polymer Grouting Materials Under Acid And Alkali Corrosion Environment

Non-water reaction foaming polymer grouting material is a kind of maintenance and reinforcement grouting material with good comprehensive performance,which has been widely used in the field of infrastructure.The mechanical properties of the nonwater reaction foaming polymer grouting material subjected to different chemical corrosion are the theoretical basis for evaluating the long-term performance,which,however,is not clear yet.Here,the influence of acid and alkali corrosion environment on the mechanical properties of polymer grouting materials under uniaxial compression was studied.Based on the Lemaitre strain equivalence hypothesis,the statistical damage constitutive model under the coupling effects of chemical corrosion and the external load was established.Combined with scanning electron microscopy,infrared spectroscopy,and molecular dynamics simulation methods,the mechanism of mechanical degradation of polymer grouting materials after acid and alkali corrosion was revealed from the microscopic point of view,and the acceleration coefficient of the indoor immersion test was preliminarily explored theoretically.The main achievements and conclusions are as follows:1.The stress and strain curves of polymer grouting material samples under uniaxial compression can be divided into five stages,namely initial compression,linear elasticity,yield,yield plateau,and strain hardening.Results show that the water brings little influence whereas both the acid and alkaline environments degrade the strength of PU grouting materials,and the longer the chemical corrosion time is,the greater the decrease in strength.2.Based on the Lemaitre strain equivalence hypothesis,the Weibull distribution function is used to define the damage of polymer grouting material under uniaxial load,Results show that the theoretical prediction curve is in good agreement with the experimental curve in the elastic stage and yield stage.In addition,based on the measured stress-strain curves,statistical damage constitutive models suitable for two different types of stress-strain curves are established.The statistical damage constitutive model under the coupling effects of chemical corrosion and the external load established in this study can predict the change of stress-strain curves of polymer grouting samples under uniaxial load after acid and alkali solution immersing for different times.3.After immersing in acid and alkali solution,the absorption peaks of various groups in the IR spectra of polymer grouting materials are obviously weakened,such as ester bond,carbamate bond,urea bond,etc.In addition,the absorption peak strength of groups with better stability(such as benzene ring)is also significantly weakened.Matetial Studio was used to establish the whole atom model and the molecular dynamics model of four states.The simulation results were consistent with the macroscopic test results.