顺层边坡岩体爆破对软弱层性态的影响研究

Effect of Blasting of Layered Slope Rockmass on Characters of Weak Intercalation

研究并确定开挖爆破对顺层岩质边坡软弱层性态的影响规律是正确进行边坡稳定性分析及其支挡设计的前提。结合现场浅孔爆破层裂试验,利用LS-DYNA3D程序模拟研究浅孔爆破时软弱层性态的变化特征。探讨距爆源不同位置处软弱层充填物的位移分布、压密度及其变化规律,给出了爆破造成层面破裂的临界位移值0.1 mm和充填物压密度的近似计算公式。此外,在模拟计算相同地质条件下深孔爆破的层裂效应基础上,分析比较了深孔爆破和浅孔爆破对软弱层性态影响的差异及其原因。研究结果表明,浅孔爆破在软弱层中形成上下左右4个方向稍微突出的近似圆形爆腔,其半径约为28.7 cm;而深孔爆破的近似圆形爆腔,其装药后方半径(89.1 cm)远小于其他3个方向半径(138.7 cm),且软弱层上下表面向后卷曲厉害;随着爆源距的增大,软弱层的位移逐渐减小,并且浅孔爆破和深孔爆破在爆源距分别小于40 cm、100 cm时,位移随爆源距的降低速度很快;软弱层的压密度在爆源附近较大,而且降低速度也很快,随着爆源距的增大,压密度逐渐减小。

To investigate and determine the effect of excavation blasting on the characters of the weak intercalation in the layered rock slope is the prerequisite for correctly carrying out the slope stability analysis and its retaining structure design The authors, in combination with the site short-hole lamination blasting test, investigated the change in the weak intercalation characters during short-hole blasting by LS-DYNA3D simulation, discussed the displacement distribution, compactness and change law of the weak intercalation at positions with different distances away from the blasting source, and deduced the critical displacement value （0.1 mm） leading to the lamination breakage by blasting and the approximate calculation formula for the compactness. Furthermore, based on the simulation of the lamination breakage effect of long-hole blasting under the same geological conditions, the difference between and causes of long-hole and short-hole blasting in the effects on weak intercalation characters were analyzed. The investigation results show that short-hole blasting forms nearround blasting cavities with about 28.7cm radius that are slightly projecting in upper, lower, left and right directions, while in the case of long-hole blasting, the near-round blasting cavity behind the charge has a radius （89. 1cm） that is far smaller than that （ 138.7 cm） of the cavities in the other three directions and the upper and lower surfaces of the weak intercalation strongly backward curves. With the increase of the distance to the blasting source, the displacement of the weak intercalation is gradually decreased and when the distance is smaller than 40 cm in short-hole blasting and 100 cm in long-hole blasting, the displacement decreases very rapidly with the decrease of the distance. The compactness of weak intercalation is high near the blasting source and decreases rapidly and with the distance increase, the compactness decreases gradually.