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.
The keyword LOAD_BLAST in LS-DYNA has been established to simulate the response of the structure under blast loading since V960. The ConWep algorithm in it is described in this paper. As the load and impulse computed by keyword LOAD_BLAST are smaller than those they should be, the accuracy and reliability of parameters in keyword LOAD_BLAST should be verified and adjusted according to the experiment results of the blast loading on blast door. The results show that the load and impulse computed by ConWep module in LS-DYNA will be close to the experimental results when the TNT equivalent in keyword LOAD_BLAST is multiplied by a factor of 1.35.
Operating safety of adjacent pre-constructed pipeline must be insured when the crude oil and refined oil pipeline is under construction. Applying finite element method, the peak velocities of observed points located at test segment and operating segment of West to East Gas Transmission Pipeline were calculated, and the ratio of the two peak velocities in different relative positions was also obtained. Taking advantage of quantitative relationship between the detonation charge and vibration velocity of particle on the pipeline, the ratio of detonation charge is derived from the peak velocity ratio, thereby the blasting scheme of West to East Gas Transmission Pipeline with different thickness is ascertained. This method is not only economical and convenient, but also has no damage to the pipeline, which also works for other blast schemes of different conditions.
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