Field test and elastic dynamic response analysis of shallow-buried utility tunnel under explosion load

In order to study the load distribution rule, dynamic response and failure mechanism of the tunnel structure under explosion load, evaluate the protection potential of the tunnel project, and obtain the test data of the tunnel under explosion load, the anti-explosion test of the tunnel structure is designed. This paper mainly analyzes the dynamic response at the center of the roof under three working conditions of the proportional blasting depth of 2.000, 1.587 and 1.260 mike. The test measures the size of the blasting pit, the time-history curves of the longitudinal bars and stirrup at the bottom of the roof center and the inner stirrup at the center of the side wall, acceleration time-history curve, reflection pressure time-history curve and displacement time-history curve. The test data show that the stirrup strain at the bottom of the roof center is much greater than that of the longitudinal bars, and the repeated displacement caused by the vibration of the tunnel is about the same. It is suggested that the tunnel should be symmetrical reinforcement and stirrup encryption, and ensure the compressive strength of concrete. The accuracy of the peak of reflected pressure is verified by the conventional weapon effect calculation software CONWEP, and the total pressure acting on the tunnel is further obtained and converted into uniform load. The maximum displacement of the roof center in the elastic response stage is calculated, which is in good agreement with the measured displacement.