Behavior of Underground Shell Structure under Seismic Impact from Explosion

The study presents the results of in-situ experimental investigations on the propagation of explosive seismic waves in the ground environment and the behavior of a seismically stressed underground structure in the form of a cylindrical thin-walled shell interacting with the ground during seismic impact from underground instantaneous explosions. It was taken into account that the seismic impact of an underground explosion on an underground structure depends on many factors, especially on the physical and mechanical properties of the soil of the experimental site. The composition of the soil was obtained by drilling holes for explosives from an excavated trench for installing samples of underground structures. Ground vibrations during the explosions were recorded at two points: at the main ( N 1) observation point and at the control ( N 2). Steel samples have been selected as the objects for studying the stress-strain state of underground structures in the form of cylindrical thin-walled shells of a closed section. The kinematic parameters of ground vibration were measured using seismic detectors and an oscilloscope. Ground displacements in three mutually perpendicular directions, which do not follow a linear law, are studied. Mathematical expressions have been selected to describe each of the components of the displacement vector. It is established that the longitudinal component in the equivalent state has a smoother decreasing character. Under the impact of underground explosions, the underground structure vibrates in space in a vertical plane and in two horizontal planes, with an increase in the equivalent distance, the range of vibrations is wider than the others, and the time of action of the waves on the structure increases. The values of logarithmic decrements for each component of the displacement vector of the structure are determined.