Blast Vibration Effect And Initiative Control Of Vibrational Damage

With extensive application of blast techniques, more and more attentions are focused on the influence of blast vibration, i.e. the ground vibration caused by blast, on the surrounding environment and the constructions, and the blast vibration damage has become an important problem of environmental protection in economic development, so researchers of many countries have made hardly unremitting investigation and exploration to it. However, due to its strong randomicity, fuzziness and uncertainly, even a problem such as transmission laws of blast vibration waves has not yet been cognized perfectly. Especially, the study on the control of blast vibration damage is still in the air, and many problems need to be solved and consummated immediately. Aimed at the aforementioned problems, based on the foregone researches, the author brought forward a new studying subject on the blast vibration effect and its initiative damage control, and carried out systematic deep-going study based upon a vast amount of monitoring data from engineering blast.At first, considering the blast vibration signal to be a short-time non-stationary random signal, the author creatively carried out a time-frequency analysis by the wavelet packet analysis technique under different conditions from the point of view of energy analyzing, and concluded that the energy distribution of blast vibration signal varies with blast conditions during its propagation, and further pointed out the characteristic of propagation of blast vibration wave.On the basis of analyzing by using kinetic theory, the author considered that blast vibration is a course of dynamical response. For the first time, the response spectrum of blast vibration was calculated by using analytical expression of trigonometric interpolation, and the influence of explosion parameters on response spectrum of blast vibration was principally explored. The results showed that response characteristics of blast vibration have marked differences in singledecked charge and multi-decked charge blast; Multi-decked charge blast technique not only takes on good effects on wave interference, but also increases the probability of selective magnification in the structural response on blast vibration at the same time, and the effect of selective magnification to blast vibration wave varies from each construction.The key to achieving initiative control of vibration damage by means of wave interference is to ascertain reasonable delay time interval. For the first time, the author made use of time-energy density analysis based on wavelet transform and time-frequency domain transform techniques, and obtained the reasonable delay time interval by separating every sub-signal from measured millisecond blast vibration signal and comparing the superposition effect of sub-signal in different delay time interval. It can be concluded that the reasonable delay time interval isn't generally a single value, but multi-time-intervals.After analyzing the relevancy to the integral of the time-energy density (TEDI) and three factors of blast vibration, the author creatively put forward the quantitative index to evaluate strong and feebleness of blast vibration effect with TEDI. Using a fuzzy neural network forecasted TEDI according to the measured vibration data, and a preliminary unified criterion for damage induced by blast vibration was constituted. When TEDI reaches 15, blast vibration begins to damage the constructions, and the feasibility and reliability of the criterion were validated by several instances. This criterion reflects the essence of blast vibration damage more comprehensively than the theory of independent threshold value and safety criterion considering the effect of frequency.Standing at the front of blast sciences, the blast vibration effect and initiative control of blast vibrational damage were studied by the author of the dissertation using newly numerical methods and means in the course of research work. It shows a high theoretical and practical value, and established a theoretical and tec...