Analysis On Disease Cause And Study On Treatment Method Of Highway Tunnel Lining In Sulphate-rich Environment

With the country’s vigorous advancement of infrastructure construction in the Western China,the number of tunnels built in the Northwest region has gradually increased.Due to the complex geological and hydrological conditions in the Northwest region,many disease problems will occur during the operation of the tunnel or when it is not put into use.Based on the on-site disease problems in a highway tunnel project in Gansu,this paper aims at combing with the corrosion mechanism of sulfate on concrete to analyze the causes of these problems and using the indoor tests and numerical software to determine the causes.The disease problems mainly include lining cracking,lining corrosion,lining side wall strength reduction,etc.In this paper,the author carries out the anti-corrosion test for the anti-corrosion concrete used in the regulation project,simulates the anti-corrosion performance of the anti-corrosion lining after the renovation,and proposes the quality control requirements of the anti-corrosion concrete based on the grey relational theory.Finally,the prevention and control measures for sulfate erosion are put forward.Firstly,aiming at the site disease of a highway tunnel in Gansu,the author learns from other domestic tunnel disease causes and uses the methods of lining strength testing and groundwater quality testing combining with the geological and hydrological conditions of the project location to initially work out the cause of the lining cracking disease.Secondly,the author carries out indoor tests in which he uses groundwater and clean water to soak the concrete test block and analyze the corrosivity of the groundwater to the concrete test block.He takes the on-site disease situation and the sulfate erosion mechanism into consideration to determine the sulfate erosion type of the tunnel in Gansu.Thirdly,according to site excavation and on-site inspections,the author uses the discrete element numerical software to simulate on-site diseases and summarized the deformation and force distribution of the initial support and secondary lining structure after sulfate erosion in groundwater.Then the author compares the numerical simulation results with the on-site disease situation to further determine the cause of the disease.Fourthly,the author analyzes the influencing factors of sulfate erosion and conducts a 180 d accelerated corrosion test of 5% sodium sulfate solution on the on-site anti-corrosion concrete to verify the anti-corrosion performance of the anti-corrosion concrete used on the site.And based on the grey correlation theory,he determines the concrete’s sulfate erosion resistance Sensitive factors and put forward on-site quality control requirementsFifthly,for the anti-corrosion concrete in the disaster-resistant section,the author uses the discrete element software to simulate the deformation and force of the lining structure after treatment when the strength of anti-corrosion concrete reaches 75%,and the improvement effect of anti-corrosion lining is analyzed.Sixthly,based on the research results of a highway tunnel in Gansu,the author proposes the prevention and treatment measures for sulfate erosion in newly-built tunnels.