一种量测松散介质对应力波衰减效应的实验方法及其在珊瑚砂中的应用

砂土等松散介质对在其中传播的应力波有非常明显的衰减作用，因此，松散介质常常作为爆炸波消波材料被广泛应用于防护工程中。为了准确地量测松散介质对应力波的衰减效应，基于并改进了传统SHPB装置，提出了一种定量研究应力波在砂土介质中衰减规律的新方法。该文方法适用于所有在冲击荷载的应变率范围内（约1~102 s-1）应变率效应不明显的松散介质。方法基于拟合的透射系数T₂，通过杆中的三波（入射波、反射波和透射波）计算得到试件两端真实的峰值应力，还可以计算试件的弹性波速、峰值应力速度、试件端部应力波的前沿升时等关键参数，简单实用，可操作性强。采用提出的方法，对干燥珊瑚砂进行了应力波衰减实验，得出了应力波荷载峰值随传播距离的衰减规律。经对比实验与参数讨论发现，拟合透射系数引起的结果误差不超过2.83%，具有很好的可靠性与实用性。

A TESTING METHOD ON THE ATTENUATION OF STRESS WAVES IN LOOSE POROUS MEDIA AND ITS APPLICATION TO CORAL SAND

Stress waves exhibit excellent attenuation characteristics when propagating in loose porous media, which is commonly used for wave mitigation in protection engineering. In order to accurately measure the stress wave attenuation effect of loose porous media, a new method to quantitatively study the attenuation of one-dimensional strain waves in loose porous media by an improving SHPB device was presented. The proposed method is suitable for loose porous media that is independent of or insensitive to strain rate within the range of strain rate of impact load (about 1-102 s-1). Based on the fitting transmission coefficient T₂, the true peak stress at both ends of the specimen could be calculated by three waves (incident wave, reflected wave and transmitted wave) in the bars. Other key parameters, such as the elastic wave velocity, the peak stress velocity and the rise time of the stress wave at both end of the specimen, can also be tested by the method. By using the new testing method, the stress wave attenuation in dry coral sand was tested. Parametric analysis shows that the error of the fitting transmission coefficient of T₂ was less than 2.83%, indicating satisfactory reliability and practicability of the proposed method.