爆源近傍の岩盤中に生じる動的応力について

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  • On the Dynamic Stresses within a Rock Caused by an Explosion
  • バクゲン キンボウ ノ ガンバン チュウ ニ ショウジル ドウテキ オウリョク ニ ツイテ

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In this paper the authors presented the results of the experiments in which the dynamic stresses within a rock caused by an explosion were measured. The dynamic stresses, γγ, θθ and ΦΦ, were calculated using the following relations derived from the theory of elasticity, _??_where U (γ, τ) =radial displacement, υ(γ, τ) =rate of change in radial displacement with time, γ=distance from the shot point, cL=propagation velocity of the longitudinal wave, λ, μ, =Lame's constants.<BR>The experiments were carried out in a tuffacious rocks bearing copper ores and a 45g-cartridge of No.3 Take dynamite or Tokugiri dynamite was used as an explosive in each measurement. The results obtained are briefly shown below.<BR>As to the characteristics of the dynamic stresses, it was found that the radial stress near the shot point (γ<about 1.5m) acted as the nonoscillatory compressive stress and this wave shape was almost similar to that of the radial displacement, but at about 2 meters distant from the shot poins, the wave length decreased rapidly and this stress became oscillatory, and the shape of the radial stress approached gradually to the wave shape of the rate of change in the.radial displacement with time with the increase of the distance from the shot point. On the other hand, the tangential stress started generally as the compressive stress, but it changed to the tensile stress at once, and its maximum value acted as the tensile stress. It was recognized that these characteristics agreed with those obtained from the theoretical calculation using Sharpe's theory. The values of about 600kg/cm2 and 100kg/cm2 were presumed respectively as the radial and tangential peak stresses at the point 0.5m distant from the shot point, and by comparing theses values with the results of the crater tests, which was carried out at the neighbouring place where the stress wave had measured, it was found that magnitudes of the stresses estimated by these experiments were reasonable.

収録刊行物

  • 日本鑛業會誌

    日本鑛業會誌 77 (882), 1047-1054, 1961

    一般社団法人 資源・素材学会

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