Air velocity u AP - air shock wave overpressure, Pa; P0 - undisturbed air pressure, Pa; C. an undisturbed air envelope speed, (= 331 (1 + 7546), m / sT. an undisturbed air Temperature, C; P - compressed air density, kg / m3; an air adiabatic index, r = 1.4. Using the above theory, estimate the example in the first section: 160m reinforced concrete chimney demolition blasting in Linxi Hexi Thermal Power Plant, Shanxi The occurrence of air shock wave damage, estimated from the strength and damage of the site wall, the effect of the air shock wave overpressure 4 households = X105Pa, if the air at normal temperature speed (:. = 331, P = 1.25kg / m3, the application of public, only When it is blasted and collapsed, all parts of the barrel can be fully broken, so that the compressed air in the cylinder can be shunted out from all directions, in order to reduce the intensity of the compressed air shock wave. In particular, to avoid the chimney landing, the first part in the middle of the chimney The impact compression causes the compressed air to be concentratedly ejected from the top of the chimney or from the broken root cylinder to form a strong directed air shock wave, which would otherwise cause damage in the above example. Therefore, when using the chimney blasting incision to surround the wall to protect the flying stone, the wall position should not be too large to leave the wall of the chimney, generally 3050cm, the height of the wall should not exceed 3m, and the wall is preferably made of soft, high porosity material. For example, ash and soil, sand and other bags are piled up; when the cushion layer is laid in the direction of collapse of the bacon, the sandbags are piled into strips, and the spacing of the strips is not too large, generally 810m, all The height of the strip dyke should be the same, not more than 3m. For the building blasting, in addition to the protective covering at the blasting site, soft materials such as straw mats, straw bags, woven bags, etc. should be used on the “relieved†doors and windows. Enclosure is carried out to reduce the strength of the compressed air shock wave when it escapes; there is a need to focus on the protection of the building facilities. When using barrier protection, the structure of the barrier should have a certain strength, and the position of the barrier should be appropriate. Keep a certain distance to prevent damage to the building facilities if the barrier is pushed down by the air shock wave.
For high-rise structure blasting (such as reinforced concrete chimney), in addition to the protective covering of the chimney blasting incision, the orientation window of the chimney, the flue of the incision part, the pre-opening window, etc. shall also be covered to protect against the shock wave of compressed air. Concentrate the escape and reduce the shock wave intensity; when there are building facilities on both sides and the rear of the collapse direction, it is necessary to set up the barrier protection, but also to ensure the structural strength of the barrier, and prevent the barrier from being damaged by the shock wave and causing damage to the protected object.
1 cited from. CK Savinke waited, Long Weiqi, translated in Aaron. Downhole air shock wave (M). Beijing. Metallurgical Industry Press, 1979.
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