Load-bearing Performance Deterioration Of Rusted Reinforced Sprayed Concrete Rib And It’s Damage Evaluation

The reinforced shotcrete arch rib support structure is widely used in the weak surrounding rock of underground engineering at home and abroad due to its advantages of convenient construction and economic efficiency.The arch rib support structure is in a complex environment.The airside side is affected by the carbonization of the concrete,and the surrounding rock side is eroded by the migration of chloride salt for a long time.The internal threaded steel bars of the arch rib are prone to corrosion,which causes durability damage to the reinforced sprayed concrete arch rib.The load-bearing performance of the arch ribs is reduced,and even causes the failure and instability of the surrounding rock.Corrosion of steel bars has become a major disease affecting the normal service of reinforced shotcrete arch ribs.In order to explore the effect of steel corrosion on the bearing performance and structural damage of in-service reinforced shotcrete arch ribs,this paper establishes a calculation model for the bearing capacity of corroded arch ribs based on the limit equilibrium theory,and obtains the law of degradation of the bearing performance of corroded arch ribs;based on the load structure The rigid-end hingeless arch model is established based on the method principle to study the internal force-deformation evolution characteristics of the corroded arch ribs;according to the stress state of the corroded arch ribs at different sections,the damage coefficient is introduced to evaluate the damage degree of the arch ribs with different degrees of corrosion.The main conclusions are as follows:(1)A calculation method for the bearing capacity of corroded reinforced shotcrete arch ribs has been established.The influence of steel corrosion deterioration on the bearing capacity of arch ribs is analyzed.According to the stress state of the arch ribs under eccentric compression,the calculation method of the bearing capacity of corroded arch ribs is deduced based on the limit equilibrium theory.(2)Analysis of mechanical response of reinforced shotcrete arch ribs with different corrosion degrees.The reinforced sprayed concrete arch rib is simplified as a solid-end hingeless arch.Based on the uniform corrosion of the steel bar in the arch rib,the influence of the corrosion of the steel bar on the stiffness and thickness of the arch rib is considered.The structural mechanics method is used to derive the internal force and deformation of the corroded arch rib.Analyze the solution,compile the corresponding calculation program,and conduct textual research,use the calculation program to study the distribution law of internal force and deformation of the arch rib with different degrees of corrosion.(3)Damage assessment of reinforced shotcrete arch ribs with different corrosion degrees.Taking the extent to which the stress state of the corroded arch rib reaches the ultimate bearing capacity as the evaluation index,the quantitative damage coefficient is introduced,and the corresponding relationship between the bearing capacity and the durability damage is established,and the damage state of the arch rib with different corrosion degrees is quickly evaluated.