Salt Corrosion Resistance Of Tunnel Lining Concrete Under Groundwater And Load

The damage of salt erosion is one of the main factors for the performance deterioration of tunnel lining concrete.The remarkable feature of the tunnel structure is that it is buried below the surface of the earth.Its actual service behavior is closely related to the geological environment conditions in service,and the influencing factors are extremely complex.Therefore,it has important practical significance to carry out the salt corrosion damage of tunnel lining concrete reasonably and accurately.Based on the background of the salt corrosion damage of the lining concrete of the tunnel structure,considering the corrosion effect of the flowing groundwater on the lining concrete and the influence of the surrounding rock pressure at different load levels on the lining concrete,the research on the salt corrosion damage of the lining concrete of the tunnel is carried out.The research content mainly includes:（1）In view of the complexity of the service environment of the tunnel structure,the laboratory simulation method is adopted,considering the typicality of the salt erosion medium(Cl^-and SO₄^2-)and the particularity of the salt erosion environment factors（groundwater flow dynamics,surrounding rock pressure）.The macro performance degradation law of the lining concrete under the complex salt erosion environment is studied.Based on the comparison of the Degradation Laws of the macro performance of the lining concrete under different salt erosion environment factors,the quantitative characterization of the influence of groundwater flow dynamics and load on the degradation of the macro performance of the lining concrete is realized.（2）Considering the effect of the flowing groundwater and the load,the experimental study on the diffusion of chloride ion and sulfate ion in the lining concrete was carried out.The content of free ion and total ion in erosion lining concrete is analyzed.The influence of the binding capacity of chloride ion and sulfate ion on the ion transport behavior in lining concrete was studied.By introducing the influence coefficient of groundwater erosion and load action coefficient,the chloride diffusion model and the calculation model of the diffusion coefficient of lining concrete under different coupling factors are established.（3）By means of X-ray diffraction,thermal analysis and scanning electron microscopy,the microstructure and phase analysis of lining concrete after salt corrosion damage were characterized.According to the results of micro test,the mechanism of salt corrosion damage of lining concrete caused by flowing ground water,load and the amount of fly ash and silica fume is expounded in detail.