TIME-SERIES ANALYSIS FOR DETERMINING VERTICAL AIR PERMEABILITY IN UNSATURATED ZONES
TIME-SERIES ANALYSIS FOR DETERMINING VERTICAL AIR PERMEABILITY IN UNSATURATED ZONES
复制标题
确定不饱和区域垂直透气度的时间序列分析
DOI：
10.1061/(asce)1090-0241(1999)125:1(69
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发表时间：
1999
影响因子：
3.9
通讯作者：
N. Lu
中科院分区：
文献类型：
--
作者：
N. Lu
当气压随时间变化时，非饱和地下的气压动态变化。取决于材料性质和边界条件，大气压力和地下压力之间的相关性的强度可以在两个持续模式中得到证明：（1）振幅衰减;和（2）主要模式的相位滞后，例如周日、半日和8小时潮汐。振幅衰减和相位滞后通常取决于可分为两类的性质：（1）大气压力参数，例如由大气潮汐等控制的视压力振幅和频率;以及（2）多孔介质的材料性质，例如空气粘度、充气孔隙度和渗透率。基于叠加原理和傅立叶时间序列分析，给出了一种预测大气压力波动引起的地下气压变化的解析解。利用计算得到的振幅衰减（或相位滞后）和大气参数与多孔介质参数之间的适当解析关系，可以定量地确定空气渗透率（或气动扩散率）。利用实测资料的分析表明，傅立叶时间序列分析可为预测地下气压变化和确定非饱和带空气渗透率提供一种潜在的可靠和简单的方法。«少
The air pressure in the unsaturated subsurface changes dynamically as the barometric pressure varies with time. Depending on the material properties and boundary conditions, the intensity of the correlation between the atmospheric and subsurface pressures may be evidenced in two persistent patterns: (1) the amplitude attenuation; and (2) the phase lag for the principal modes, such as the diurnal, semidiurnal, and 8-h tides. The amplitude attenuation and the phase lag generally depend on properties that can be classified into two categories: (1) The barometric pressure parameters, such as the apparent pressure amplitudes and frequencies controlled by the atmospheric tides and others; and (2) the material properties of porous media, such as the air viscosity, air-filled porosity, and permeability. Based on the principle of superposition and a Fourier time-series analysis, an analytical solution for predicting the subsurface air pressure variation caused by the atmospheric pressure fluctuation is presented. The air permeability (or pneumatic diffusivity) can be quantitatively determined by using the calculated amplitude attenuations (or phase lags) and the appropriate analytical relations among the parameters of the atmosphere and the porous medium. An analysis using the field data shows that the Fourier time-series analysis may provide a potentially reliable and simplemore » method for predicting the subsurface barometric pressure variation and for determining the air permeability of unsaturated zones.« less