地形影响地面运动的观测研究

AN OBSERVED EFFECT OF TOPOGRAPHY ON SURFACE MOTION

本文利用矿山爆破,进行了地形对地面运动影响的观测研究.9次爆破的结果表明,山顶处位移和速度的谱曲线的峰区较山前和其它测点的集中,振幅的量值也大,其放大倍率约为3,其中与山体走向平行的水平分量放大得最大,与之垂直的次之,而垂直于地面的最小;山顶测点不同分量上最大位移所对应的周期接近,其对山前的放大量值近于2,也是水平分量大于垂直分量;山顶处地面运动的延续时间取决于爆破的药量和方式,山前等测点延时的放大为3—4倍,也是水平分量大于垂直分量.山顶上地面运动的这种特殊性,是由于入射波所激发的山体共振所引起的.

An explosion seismic observation war, cairied out from tops to feet of two long narrow-mountains by ten sets of seismometers whicn measure ground displacement and velocity separately in order to study the effect of topography on surface motion. From 9 explosion records,, it appeared that the peak values in displacement and velocity spectrum on the mountain tops were greater than those at the mountain feet and other points, and the peak area was more concentrated too. The amplification ratio (2.6) for the component perpendicular to the ridge strike was less than that (5.0) parallel to the ridge strike and greater than the vertical one (2.0). The periods (0.5s) corresponding to the maximum displacements in different components on the mountain tops were nearly constant, and the amplification ratio (1.9) for horizontal component was larger than the vertical one (1.6). The vibration delay time on the mountain top, which depended on explosive charge and method, was greater than that at other points, the amplification ratio possessed similar character with the period's ratio.The character of surface motion on moutain top was attributed to the resonance of these mountains.