Papers by Keyword: Ground Shock

Abstract: Numerical simulations of rock-buried tunnel collapse under plane pulse loads propagated from ground were performed using the nonlinear FEM software of LS-DYNA, the difference of structure collapse between the cases with initial stress-strain conditions being concerned and not concerned was observed. The calculations indicate that, provided other conditions are equal, when initial state is taken into account the collapse is more serious than that regardless of initial conditions. Initial stress-strain state has much influence on the underground structure’s dynamic response, hence the initial conditions should not be ignored when doing dynamic analysis of underground structures.

Abstract: Empirical formula can be used to get ground shock parameters produced by conventional weapons buried in soil medium. With the development of finite element technology, ground shock parameters can be obtained by numerical simulation. However, sometimes the numerical simulation results were not consistent with the empirical formula results. A two-dimensional axial symmetry model and a three-dimensional model were set up to calculate the ground shock from a fully buried spherical charge, numerical results and empirical formula results were compared and the causes of the calculation error were analyzed.

Abstract: Going underground has been proven an effective defense strategy. However, defense structures below the ground need to be designed for ground shock loading. In Singapore, two thirds of the land area is covered by residual soils which are mostly unsaturated. But soil moisture condition in a tropical country like Singapore can alternate between dry and wet conditions. This paper summarizes the findings of a series of small-scale field tests to investigate the effects of degree of saturation on ground shock. A new perspective is presented which will help in developing technologies to mitigate ground shock effects on underground structures in future.

Abstract: To reduce safe distance such as inhabited building distance (IBD), a new type magazine, which is referred to as a subsurface magazine, has been proposed and the explosion effects have been discussed. We have conducted explosive tests by using relatively large scale models (23 kg and 78 kg in mass) and examined mass effect (scale effect) of blast waves caused by explosion of high explosives. The magazines were composed of a arch-type explosive storage room with a line hinge along the top of the roof of the wall, a square passage way to ground which will release the blast wave. Explosion hazards from the explosion of subsurface magazines were collected to understand the characteristics of airblast, fragments, and ground shocks. Safety criteria for the subsurface magazine are discussed based on the experimental results.