Study On Anti-explosion Performance And Mechanism Of RC Straight Wall Arch Reinforced By SPUA

As a commonly used component in underground engineering,RC straight wall arch is widely used in defense tunnels,tunnels,weapon caverns,missile silos and underground command posts.Since the sheltering work is usually strategically important,the RC straight wall arch is the focal point of the enemy attack.It is of great military significance to explore an effective method for strengthening and repairing RC straight wall arch structure and to enhance the anti-strike capability of underground engineering structure.In this paper,the explosion resistance of RC straight wall arch strengthened by polyurea elastomer and the residual bearing capacity after repaired by concrete repairing glue are studied by model test,and the damage process and mechanism of RC straight wall arch under explosion load are revealed by numerical simulation.The main work and results are as follows:(1)Considering the influence of concrete strength,polyurea elastomer reinforcement thickness and location of the explosion point,the experimental study on the anti-explosion performance of RC straight wall arch was carried out.The results show that the improvement of concrete strength can improve the anti-explosion performance of RC straight wall arch,which is reflected in the reduction of damage parameters.At the same time,the increase of concrete strength also increases the brittleness of the specimens to a certain extent,which is reflected in the slight increase of the number of cracks.The impact point position has no significant effect on the anti-explosion performance of the specimens.The coating of polyurea elastomer can significantly improve the anti-explosion performance of the specimen and play a certain role in energy absorption.The solid connection between polyurea elastomer and concrete can effectively prevent the flying of cracked concrete,and the effect is better with the increase of coating thickness.(2)The numerical simulation study on the damage mechanism of RC straight wall arch under contact explosion was carried out,and the influence of explosive equivalent and explosion distance on the size of RC straight wall arch fracture was carried out.RC straight wall arch specimen under the action of 200 gTNT explosion load showed local failure at the blast point,the failure mode is the bursting surface blasting and the backburst surface cracking.The bursting surface blasting pit is mainly caused by the strong compression of the shock wave to make the concrete reach the dynamic compressive ultimate strength;the backburst surface blasting pit.The sparse waves formed by the reflection of the compression wave on the free surface cause tensile damage to the concrete.Under the contact explosion,the fracture size increases with the increase of charge.Under the non-contact explosion load,the size of the fracture has little difference from the direction of the stirrup and the direction of the stressed reinforcement,and both decrease with the increase of the detonation distance.(3)The residual bearing capacity of RC straight wall arch after blast repair is studied.The JN-CE concrete repairing glue was used to repair the blasting and concrete caving parts of the top surface and the bottom surface.The residual bearing capacity test was carried out by means of dome loading.The results show that the failure mode of the test piece is: the shearing damage of the reinforced concrete,the shearing damage of the repairing glue,the shear failure of the reinforced concrete accompanied by local damage and bending failure,the residual bearing capacity of different failure modes are different.