Confined blast loading occurs in many scenarios and the effects of confined blast loading may result in more serious damage to buildings due to multiple shock reflections (Shi et al. 2009). However, spherical charges are assumed for all confined explosive-effects computations in modern standards for blast-resistant design such as UFC-3-340-02 (2008) and the soon-to-be published ASCE Standard for the Blast Protection of Buildings (ASCE forthcoming) without consideration of effects of charge shape on the distribution of reflected overpressure and impulse. As confinement is an aggravation factor of explosion effects, analysis and design of infrastructure under critical scenarios of confined blast loading should take the aggravation factor into consideration. This paper is to develop a numerical model for prediction of blast loads inside unvented structures as a result of variation of the charge shape, charge orientation, geometries and volumes of confined chambers. A finite element program, AUTODYN (Century Dynamics, 2003), is utilized extensively to generate a model which is capable of being calibrated with the experimental results conducted by Wu et al. (2010) in external conditions and by Zyskowski et al. (2004) in a confined small box. The calibrated AUTODYN model is then used to conduct parametric studies to analyze the effects of the variation of charge shape, charge orientation, chamber geometry and chamber volume on the peak reflected overpressure and impulse on the walls of the chamber. The quasi-static overpressure for fully confined blast loading is characterized and the simulated results are used to derive the relationships between the quasi-static overpressure and scaled distance for the fully confined blast loading. Discussion is made on characteristics of fully confined blast loading inside chambers.

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To study the lining deformation characteristic of the cold region tunnel under the frost heaving force, a model test was designed, and the low temperature environment in the tunnel of model was made by refrigeration equipment, the groundwater inside the model was frozen, the lining structure deformation characteristic under the frost heaving force was analyzed. The results show that the lining was distorted under the frost heaving force, the lining strain of the tunnel crown and side wall was greatly, the maximum strain is 122μ, the lining strains of inverted arch and foot of wall was less, the minimum strain is 25μ.

Based on the response data of the frontal impact test of the trolley, the frontal impact simulation and analysis of the double-tube model of the trolley were carried out using finite element software. Starting from the thin-wall deformation mode, acceleration and energy curve changes as response indicators, the error between simulation and experiment is studied. With the goal of improving the simulation accuracy of the model, the influence of strain rate effect on the collision response is studied, and the deformation mode and acceleration curve are compared with those without strain rate and actual vehicle test. The final result shows that considering the strain rate effect is obviously better than not considering the strain rate in terms of the acceleration peak and the number of thin-wall deformation folding.