岩质深基坑爆破振动放大效应测试研究

为分析岩石深基坑爆破振动沿基坑边坡的传播规律,研究基坑坡顶不同位置处的高程放大效应,以嘉晟国际基坑爆破开挖工程及其对邻近瑞达基坑的影响为实例,在瑞达基坑坡顶边缘位置及两基坑坡顶中间位置分别布置两个测点,监测嘉晟基坑不同开挖深度下两个测点的振动效应,对振动测试数据进行回归分析,并结合实际工况对瑞达基坑坡顶边缘位置质点振动速度进行模拟。结果表明:一定高差范围内,瑞达基坑坡顶边缘质点振动速度峰值与主频随高差增加逐渐增大,超出一定高差范围后则逐渐衰减,利用现场实测与数值模拟数据对基坑边坡进行分区,爆破振动速度增大与衰减的高差临界值分别为6.21 m,8.36 m;两基坑坡顶中间位置处质点无高程放大效应;考虑高程效应的振动速度预测公式精确度优于传统的萨氏公式。研究结论对今后类似工程具有一定的借鉴意义。

Research on Amplification Effect of Blasting Vibration in Rock Deep Foundation Pit

In order to analyze the propagation behavior of blasting vibration along the slope of foundation pit,the elevation amplification effect in different slope height and influences on neighbor Ruida foundation pit was investiga-ted on Jiasheng foundation pit blasting excavation engineering.Two measuring points were arranged in the edge posi-tion of Ruida foundation pit and the middle position of two foundation pits to monitor the vibration effect in different excavation depths of Jiasheng foundation pit,and then vibration test data was treated by regression analysis.Besides, vibration velocity of measuring point in the edge position on slope of Ruida foundation pit was simulated according to actual condition.The results show that in a certain height range,the peak vibration velocity and frequency of measur-ing point in the edge slope of Ruida foundation pit gradually increased with the increasing of height,then decreased beyond a certain height.The slope of foundation pit was partitioned with field measurement and numerical simulation data.The critical height between blasting vibration velocity increasing and attenuation was 6.21 m and 8.36 m,re-spectively.There was no elevation amplification effect in the middle positions of two foundation pit.Considering the altitude effect,the accuracy of vibration velocity prediction formula was better than traditional Sadaov's formula.