高能量冲击下淤泥土体能量传递规律试验研究

Experimental study of energy transfer in muck soil subjected to high-energy impact

以往动力排水固结室内模型试验,通常冲击能量低,软土物理力学响应激发不够,难以寻求与工程实践相符的能量传递规律。利用可提供高冲击能的多向高能高速电磁力冲击智能控制试验系统,对淤泥类超软土进行静动力排水固结模型试验,获得了高能量多遍冲击作用下竖向与表层水平向能量传递规律:(1)冲击荷载下浅层土中相应土压增量始终最大,但随着夯击遍数增加,其下土层土压增幅随之相对增大;而就土层压缩量而言,首遍夯击下浅层土最大,此后中层与深层之值均大于浅层土之值,且其比值随着夯击遍数增加而增大,表明了主要压缩区向下移动;(2)静动力排水固结法中,冲击能量初始主要作用于浅层,此后随着淤泥力学性质不断沿深度方向改善,能量逐渐向下传递以主要加固下层及深层土体;(3)夯击作用下土层表面同一位置处竖向质点振动速度最大,径向次之,环向最小,且在一定的距离处趋向同一稳定值;振动加速度亦呈现相同的变化规律;模型试验得到的振动主要影响范围与实际工程一致。

Traditionally dynamic consolidation tests were performed under low-energy impact, which is not sufficient to trigger significant mechanical response of soft soil so that the laboratory tests cannot properly simulate the actual energy transfer process in the field. In this study, static and dynamic consolidation tests are performed on muck soil, using a self-developed multi-directional high-energy electromagnetic impact testing system, from which the energy transfer processes in horizontal and vertical directions are characterized under repeated high-energy impacts. The experimental results include （1） The pressure increase in shallow soil is always the largest under impact; and the pressure increment in deep soil increases with the impact number; after first impact, the compression amount of shallow soil is the largest, and then the compression amount of deeper soils exceeds that of the shallow soil; and the difference becomes larger and larger as the impact number increasing, indicating that the main compression zone moves down gradually. （2） In both static and dynamic consolidation tests, the impact energy initially acts on the shallow soil, and then transfers to deeper soils, resulting in the improvement of the mechanical properties of the muck soil in depth. （3） Under impact loading, the vertical particle velocity is the maximum, followed by the radial direction, and ring direction is minimal at the same position of the surface layer of soil, and particle velocity approaches the same stable value at a certain distance; vibration acceleration also shows the same variation law; the region under the influence of vibration observed in the model test is consistent with those of the actual engineering projects.