饱和冻土场地凹陷地形对平面P波的散射规律研究

SCATTERING OF PLANE P-WAVES BY CIRCULAR-ARC CANYON IN SATURATED FROZEN SOIL HALF-SPACE

  • 摘要: 基于饱和冻土介质波动理论,利用波函数的Fourier-Bessel级数展开法,研究平面P波入射在饱和冻土半空间凹陷地形的散射问题。通过数值算例,分析了平面P波入射饱和冻土半空间凹陷地形时入射频率、入射角度、温度(含冰量)、孔隙率、接触参数等物理力学参数对地表位移幅值的影响规律。研究结果表明:在不同深宽比和入射频率下温度(含冰量)对地表位移幅值影响显著。在不同深宽比条件下,半圆形凹陷地形相对于浅圆形凹陷地形对温度的变化更为敏感。在低频时,竖向位移随入射角度的增加而减小,水平位移随入射角度增加而增大;水平位移随孔隙率的增加而降低,但对竖向位移影响较小。随着入射波频率的增大,饱和冻土半空间凹陷地形中位移幅值的空间分布更加复杂。且随着频率的继续增大,位移幅值随入射角的变化不再明显,而孔隙率的影响逐渐增大,尤其在浅圆形凹陷地形中,孔隙率的增加导致位移幅值更为敏感。此外,在较低温度下(T=−0.7 ℃),凹陷地形表面位移幅值随接触参数的变化尤为显著,而在较高温度下(T=−0.3 ℃),水平位移和竖向位移变化不明显。

     

    Abstract: Based on the wave theory of saturated frozen soil medium, the scattering problem of plane P wave incident on the concave terrain of saturated frozen soil half-space is studied by using the Fourier-Bessel series expansion method of wave function. Through numerical examples, the influence of physical and mechanical parameters such as incident frequency, incident angle, temperature (ice content), porosity and contact parameters on the surface displacement amplitude is analyzed when the plane P wave is incident on the half-space concave terrain of saturated frozen soil. The results show that the temperature (ice content) has a significant effect on the surface displacement amplitude at different depth-width ratios and incident frequencies. Under different depth-width ratios, the semi-circular depression terrain is more sensitive to temperature changes than the shallow circular depression terrain. At low frequency, the vertical displacement decreases with the increase of incident angle, and the horizontal displacement increases with the increase of incident angle. The horizontal displacement decreases with the increase of porosity, but the porosity has little effect on the vertical displacement. With the increase of the incident wave frequency, the spatial distribution of the displacement amplitude in the half-space depression terrain of saturated frozen soil is more complicated. As the frequency continues to increase, the change of displacement amplitude with the incident angle is no longer obvious, while the influence of porosity gradually increases, especially in shallow circular concave terrain, the increase of porosity leads to more sensitive displacement amplitude. In addition, at lower temperature (T=−0.7°C), the displacement amplitude of the concave terrain surface changes significantly with the contact parameters, while at higher temperature (T=−0.3°C), the horizontal displacement and vertical displacement do not change significantly.

     

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