EI、Scopus 收录
中文核心期刊

P波入射非局部热黏弹性饱和土自由界面的反射特性研究

REFLECTION CHARACTERISTICS OF P-WAVE INCIDENT ON THE FREE SURFACE OF NONLOCAL THERMO-VISCOELASTIC SATURATED SOILS

  • 摘要: 为研究平面P波入射非局部热黏弹性饱和土自由表面的反射问题, 本文建立了同时考虑热效应、孔隙尺度效应(孔隙尺度变化与动态孔隙应力)及土体骨架黏弹性的非局部热黏弹性饱和多孔介质波动方程, 并在此基础上构建了反射P1波、反射P2波、反射T波与反射S波的振幅比及能量反射系数计算框架. 通过数值算例分析了松弛时间、热传导系数、介质温度与非局部参数对振幅反射系数与能量反射系数的影响, 进一步揭示了非局部效应与热-黏弹性耦合作用对反射波传播特性的影响机制. 研究表明: 中等入射角区间反射最敏感、耗散最强. 非局部效应与热黏弹性耦合使P1波反射减弱并导致极值角偏移, 且非局部效应抑制T波的反射, S波在非局热黏弹性模型下呈“单峰”变化规律. 引入骨架黏性后会影响引起反射波能量的分配: P1波的能量反射系数减小, P2波与T波则增大, 且P2波对松弛时间更敏感. 对于热物性参数的研究表明, P1波的反射系数随热传导系数与介质温度升高而增强, P2波则随温度升高减弱; T波的振幅反射系数随热传导系数呈正相关变化, 但能量反射系数随热传导系数与温度升高下降; S波的反射系数随温度升高减弱. 非局部参数与入射角度的耦合作用也对各反射波的反射行为调控显著, 反射P1波变化规律呈“U形”且随τ增大整体减弱; τ增大抑制反射P2波的振幅反射系数, 但会使其能量反射系数增大; 反射T波的能量反射系数随τ先增后减; S波的反射系数随τ增大同步衰减且峰值角基本不变.

     

    Abstract: To investigate the reflection of a plane incident P-wave at the free surface of a nonlocal thermo-viscoelastic saturated soil, this study formulates governing wave equations for a nonlocal thermo-viscoelastic saturated porous medium that simultaneously incorporate thermal effects, pore-scale effects (including pore-scale variations and dynamic pore pressure), and the viscoelastic behavior of the soil skeleton. On this basis, a computational framework is developed to evaluate the amplitude ratios and energy reflection coefficients of the reflected P1-wave, reflected P2-wave, reflected T-wave, and reflected S-wave. Numerical examples are then used to examine how relaxation time, thermal conductivity, medium temperature, and the nonlocal parameter influence the amplitude reflection coefficients and energy reflection coefficients, thereby further elucidating the mechanistic roles of nonlocality and thermos-viscoelastic coupling in shaping the propagation characteristics of reflected waves. The results indicate that reflection is most sensitive and dissipation is strongest within a moderate range of incident angles. The combined action of nonlocality and thermos-viscoelastic coupling weakens P1-wave reflection and induces a shift in the extremum angle; moreover, nonlocality suppresses T-wave reflection. Under the nonlocal thermo-viscoelastic model, the S-wave reflection exhibits a “single-peak” pattern. Incorporating skeleton viscosity redistributes reflected-wave energy: the energy reflection coefficient of the P1-wave decreases, whereas those of the P2 and T waves increase, and the P2-wave is more sensitive to the relaxation time. With respect to thermophysical parameters, the reflection coefficient of the P1-wave increases with increasing thermal conductivity and medium temperature, while that of the P2-wave decreases as temperature rises. The amplitude reflection coefficient of the T-wave is positively correlated with thermal conductivity; however, its energy reflection coefficient decreases with increasing thermal conductivity and temperature. The S-wave reflection coefficient decreases as temperature increases. The coupled effect of the nonlocal parameter and incident angle also exerts a pronounced regulatory influence on the reflection behavior of all reflected waves: the reflected P1-wave follows a “U-shaped” trend and weakens overall as τ increases; increasing τ suppresses the amplitude reflection coefficient of the reflected P2-wave but increases its energy reflection coefficient; the energy reflection coefficient of the reflected T-wave increases first and then decreases with τ; and the S-wave reflection coefficient decays monotonically with τ, with the peak angle remaining essentially unchanged.

     

/

返回文章
返回