Blast-induced Cumulative Damage Of Underground Structure And Safety Control Technology

With extensive application of blast techniques, the influence on surrounding environment and constructions caused by blast vibration has attracted more and more attentions. The damage induced by blast vibration has become an important problem of environmental protection in economic development. Hence, researchers from many countries have made hardly unremitting investigation and exploration to the problem. At present, few research on cumulative damage effects under blasting loadings is not enough to solve the problem of vibration damage. Many problems in theory and technology on blast need to be solved and consummated immediately. Aimed at above problems, the author counted out systematic study on blast-induced cumulative damage of underground structure and safety control technology. The main contents in the paper are as follows:1Relying on Changxiang highway project, a large amount of blasting vibration data was collected by using the international advanced blasting vibration measurement instruments. Taking the distance, explosive quantity, age of concrete and frequency into account, the cumulative damage induced by blast vibration was analyzed. Then, the computation model and evolution law of cumulative damage were established.2The critical speed which makes flaws of different length to crack in concrete of different ages was calculated. This can be used to judge whether a flaw will start to expand.3As a complement of the specified permissible velocity in "blasting safety regulations", the damage threshold of tunnel lining structure was decided in the paper to guarantee the safety of tunnel construction.4The blasting vibration transient energy curve was obtained by using HHT transform method. This curve made the observing of the blasting vibration intensity in each delay interval more intuitive, and corresponding measures to control damage can be proposed.5According to Sadowsky formula fitted from the measured blasting vibration data, the peak particle vibration velocity of the tower for the ultrahigh-tension power transmission lines on a shallow tunnel was predicted. In order to protect the tower, corresponding measurements were implemented.