土壤非饱和区含水层对潮致地下水波动的影响

Unsaturated zone aquifer's impact on tidally-induced groundwater fluctuations

针对滨海潜水层中存在的潮致地下水波动现象,以Kong等提出的新型Boussinesq方程为理论基础,通过摄动解析法剖析波动组成及函数表达,在此基础上分析土壤非饱和区含水层对潮致地下水波动的影响机制。结果表明:地下水波传入滨海潜水层后,主频波幅呈指数型衰减,且渗透系数越小波能衰减越快;在非线性作用下,波动传播过程中将衍生出高频波,波能从低频波向高频波迁移;当土壤的非饱和持水性较强、土壤层非饱和区厚度较小、土壤孔隙率较小时,有利于潜水层内高频波的形成。

Concerning the phenomenon of tidally-induced groundwater fluctuation in a coastal aquifer,based on the new Boussinesq equation derived by Kong et al.,the function express and composition of the wave were analyzed using the perturbation method. Analytical research on the influence mechanism of a tidally-induced high-frequency groundwater wave affected by the unsaturated zone aquifer was conducted. The results indicate that,after the groundwater wave propagated into the coastal aquifer,the dominant frequency amplitude decreased exponentially,and the smaller the hydraulic conductivity was,the larger the decay rate of wave energy was. Besides,under the nonlinear effect,a high-frequency wave was generated during the wave propagation process,and the wave energy transformed from a low-frequency wave to a high-frequency wave. Numerical experiment results show that the increase of unsaturated water holding capacity,the decrease of thickness of the unsaturated zone,and the decrease of porosity of soil promote the formation of a high-frequency wave.