水工岩石高边坡爆破振动安全控制标准的确定研究

Determination of safety control standard for high rock slopes under blasting vibration

确定合理的岩石高边坡爆破振动安全标准是西南地区水电工程拱坝建基面爆破开挖控制的关键。基于目前广泛采用上层台阶的爆破振动速度阈值作为爆破振动安全标准的现状,分析水电工程岩石高边坡爆破振动安全标准确定的两大依据,其一为上层台阶岩体本身的允许振动速度,其二控制当前爆破梯段保留岩体的损伤深度,建立的上层台阶爆破振动速度阈值;结果表明,现采用的控制标准明显低于边坡自身的爆破损伤允许振动速度,其确定的核心依据是控制当层梯段保留岩体的损伤深度。基于应力波的衰减机制,从理论角度给出岩石高边坡爆破安全标准确定的数学描述,结果表明振动安全标准的确定与坝肩槽允许开挖损伤深度、台阶高度均密切相关,同时由于径向应力与环向应力是爆破损伤区形成的主要原因,爆破安全标准的确定应具有方向性,以水平径向与水平切向的振动速度作为控制标准更为合理。针对岩石高边坡爆破振动安全控制标准的应用,分析上层台阶马道附近的爆破振动特性,结果表明爆破振动存在局部放大的特征;建议并验证岩石高边坡爆破振动测试方法,当采用爆破振动安全标准判别当次爆破开挖的爆破响应时,宜将爆破监测点布置在马道内侧。研究结果期望为岩石高边坡的爆破开挖安全控制提供参考。

Determining the reasonable safety standard for high rock slopes under blasting vibration is one of the keys in the excavation control of foundation surface of arch dams in the Southwest of China. Currently,the peck particle velocity of the last bench is used as the control standard. On this basis,the determination of control standard for high rock slopes was analyzed. The formation of blasting damage zone was investigated. The radial and tangential stresses are the main factors of the blasting damage. Therefore,the directions should be considered in the determination of blasting safety control standard. The velocity in horizontal radial and tangential directions used as the control standard is more reasonable. The distribution characteristics of the blasting vibration aroundthe berm was analyzed. The characteristics of the local amplification was found. A test approach of blasting vibration was proposed. When the blasting vibration control standard is used to distinguish the response of the high rock slopes,the test points should be fixed on the inside of the berm. If the most adverse effect of berm of the last bench is the target,forever,the test points must be fixed on the outside of the berm.