时程稳定性系数确定的边坡逐孔起爆孔间微差降振时间

为了获得边坡逐孔爆破最佳降振微差时间,以某个实际边坡逐孔微差爆破施工现场为原型,先利用ANSYS建立二维静态模型,借助有限元折减法确定自然状态下的潜在滑动面和静态安全系数;基于已确定的二维潜在滑动面重新建立同尺寸同性质的三维逐孔微差爆破动态模型,利用LS-DYAN进行动力分析,整个过程分别设置同排3个炮孔0、17、25、42和65 ms等5种不同孔间微差起爆方式;同时,对该施工现场进行排、孔间(25 ms,17 ms)、(25 ms,25 ms)、(25 ms,42 ms)、(25 ms,65 ms)等4种微差时间控制的等比例相似小炮测振实验。提取模拟结果中3个炮孔同时起爆时滑面单元的应力数值代入极限平衡法计算公式,绘制了冲击载荷作用下边坡稳定性系数曲线,通过对曲线的理论分析发现,最佳降振微差时间约为48 ms;而三维数值模拟和测振实验结果均显示,孔间微差时间取42 ms时降振效果较佳。这说明,边坡稳定性系数曲线给出的微差时间与模拟和实验结果较为接近,可为今后边坡逐孔微差爆破降振研究提供参考。

Millisecond time for reducing vibration between two holes for slope blasting determined by stability coefficient of time history

In the present study we found out about the optimum millisecond time for reducing vibration in hole-by-hole blasting, on the basis of an actual slope detonation work. At first we constructed a two-dimensional static model using ANSYS and determined the potential sliding surface and the static safety factor in the natural state using finite element reduction. Then we rebuilt the three-dimensional dynamic model of millisecond hole-by-hole blasting and carried out the dynamic analysis using LS-DYAN. In the whole process, we set up three holes in the same row using millisecond detonating by five differential millisecond time control of 0, 17, 25, 42 and 65 ms. At the end of the construction site, we conducted small-scale vibration tests of four millisecond time control in row holes (25 ms, 17 ms), (25 ms, 25 ms), (25 ms, 42 ms), (25 ms, 65 ms), with the stress value of the sliding surface unit during the simultaneous detonation of three holes in the simulated results taken into the formula of limit equilibrium, and drew out the time history curve of slope stability coefficient under impact loading. Analyzing the time history curve, we found that the optimum millisecond time for vibration reduction was 48 ms. Moreover, the results of three-dimensional numerical simulation and vibration test showed that the effect of vibration reduction was better when the millisecond time between holes was 42 ms. The result shows that the millisecond time, given by the slope stability coefficient, is consistent with the simulated and experimental results, which provides a reference for related research on vibration reduction of millisecond hole-by-hole blasting.