Deterioration And Durability Mechanical Properties Of Grouting-Reinforced Body Under Seawater Erosion

Along with the needs of national marine strategy and urban development,a large number of cross-sea tunnels and offshore tunnels are about to be put into construction,often encountering bad geology such as faults and Quaternary,and grouting is the most commonly used treatment method.Different from the mountain tunnel,the bad geological grouting and solidification have long been facing the adverse effects of seawater erosion,which has become a major threat to the safety of the tunnel in the past 100 years.Therefore,it is of great theoretical and practical value to study the deterioration law and durability of grouting and solidification performance under seawater erosion conditions to ensure the long-term service safety of submarine/offshore tunnels.(1)Structure and its durability.During the operation period,the construction of submarine/offshore tunnels often crosses the rich sand layer,and the curtain grouting method is an important means to ensure the safety of tunnel construction.In this paper,the grouting reinforcement ring of weak water-rich sand layer under seawater erosion condition is comprehensively tested by indoor test,simulation test,theoretical analysis and numerical simulation to study the deterioration of mechanical properties and durability,and gradually establish a certain number of years.The mechanical properties of the grouting reinforcement ring deteriorated,and the durability prediction model of the grouting reinforcement ring in the life cycle of the operating tunnel project was finally established.The research results have certain reference significance for ensuring the service safety of operating subsea/offshore tunnels.(2)Accelerated tests were carried out to carry out solidification uniaxial compression test,point load test,direct shear test,permeability coefficient test,solidification microscopic test,etc.for different test blocks,and the strength and cohesion of the solidified body were obtained within a certain period of time.Friction angle,permeability coefficient and micro－morphology change;and the solidification thickness reduction equation was established to study the equivalent reduction of the thickness of the reinforcement ring within a certain period of time;(3)Combined with the basic principle of damage mechanics,the dynamic damage factor is introduced by the deformation modulus of deformation modulus,and the dynamic damage factor curve with time is obtained.The evolution equation of damage and the mathematical model of damage are established.Combined with the Mohr-Coulomb criterion,the damage criterion of solidification damage is established,which provides a theoretical basis for the damage evolution model of grouting reinforcement ring;(4)Relying on the half-section curtain grouting section of an offshore tunnel operated by Qingdao Metro Line 13.Through the on-site or indoor test,the mechanical parameters of the reinforcement ring and the stratum after grouting are obtained.The model is established according to the thickness reduction equation of the grouting reinforcement ring,and the osmotic pressure change law of the reinforcement ring and the lining is analyzed to achieve 9000d(close to 25 The prediction of the change law of osmotic pressure of grouting reinforcement ring in the year;the model is established according to the damage evolution equation of grouting reinforcement ring,and the variation law of stress and deformation of grouting reinforcement ring and lining is analyzed under the actual formation stress.It is predicted to predict changes in stress and deformation of grouting reinforcement rings and linings in 28800d(nearly 80 years).