頁籤選單縮合
題 名 | 抽取地下水導致孔隙壓變化之探討=Investigation on Change of Pore Pressure Due to Pumping of Groundwater |
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作 者 | 施清吉; | 書刊名 | 農業工程學報 |
卷 期 | 44:3 1998.09[民87.09] |
頁 次 | 頁9-24 |
分類號 | 443.67 |
關鍵詞 | 地下水; 地層下陷; 孔隙壓; Groundwater; Land subsidence; Pore pressure; |
語 文 | 中文(Chinese) |
中文摘要 | 飽和含水層的上方與下方各有一層滲漏非常小的透水層。假設自飽和含水層抽取 地下水而導致之水流動,僅限制於平面,同時也假設只有沿垂直方向的滲漏;則在飽和含水 層內,因抽取地下水而導致孔隙壓之遞減,為擴散方程式所規範,但另含兩項,常數項與線 性項分別代表抽水量與滲漏。另外,再假設地層下陷僅來自垂直方向的壓密,則利用孔隙壓 遞減量與土層厚度變量之間的關係,就可間接求得沉陷量。針對孔隙壓的變化,分析解係由 Green函數構建求得,其結果為描述四者的相互關係:無因次空間座標、無因次孔隙壓差距 、擴散參數與遞減參數,後兩項均與時間有關。直角座標的分析解可由控制方程式直接積分 求得,其組成以誤差函數為主;而極座標的分析解只能簡化至瑕積分,無法再直接積分求得 ,被積函數係由第零階與第一階貝塞函數所組成。小於零的無因次孔隙壓差距不具意義。不 論是妨礙分析的應用,小於1.0×10的分析解均會呈現時正時負的現象,但是這並不妨礙分 析解的應用,因為1.0×10實在太小了。呈現時正時負的現象是必然的。直角座標是來自分 析解本身所含的負號,而極座標係來自其貝塞函數的特性。數值計算所涵蓋的範圍如下:擴 散參數的值為0.001、0.01、0.1與1 ;而遞減參數的值為0.0001、0.001與0.01。 |
英文摘要 | Due to the decrement of the pore pressure as resulted from the pumping of the groundwater from a saturated aquifer, confined between two weakly leaking stratum, it is assumed that the movement of the groundwater is restricted in a horizontal plane only while the leaking through the strata is limited in a vertical direction only. The decay of the pore pressure in the saturated aquifer is then described by a diffusion equation with two extra terms, the constant term representing the pumping discharge while the linear term denoting the decaying rate of the pore pressure. In addition, it is further assumed that the land subsidence is exclusively caused by a vertical settlement in the saturated aquifer. Based on the relationship between the decrement of the pore pressure and that of the relative thickness of the aquifer, the amount of the land subsidence can consequently and indirectly be determined. Analytical solutions, as constructed from the Green function, are referred to the change of the pore pressure and present a functional relationship amoung four iterms: the dimensionless pore pressure decrement, the dimensionless spatial coordinate, the diffusion parameter and the decay parameter, the later two iterms relating to the time. In the cartesian coordinate, analytical solutions, as integrated directly from the governing equation, are entirely composed of the error function. On the other hand, in the polar coordinate the governing equation can only be integral partially, and be simplified further to end up with an improper integral with an integrand consisting with the zeroth order and the first order of the Bessel functions. It is meaningful only if the value of the dimensionless pore pressure decrement as predicted by the analytical solution is greater than zero. It is found that analytical solutions will present oscillation if the value of the dimensionless pore pressure decrement is less than 1.0E-09 regardless of the coordinate systems. However, the oscillation of the analytical solution will not stifle applying the analytical solution on some other related fields, since the value of 1.0E-09 is too small. The presence of the negative value for the dimensionless pore pressure decrement is inevitable. In the cartesian coordinate system it is due to the negative operation in the analytical solutions, while in the cylindrical coordinate system it is originated from the characteristics of the Bessel functions. Ranges of numberical calculation of analytical solutions are 0.001, 0.001, 0.1 and 1 for values of the diffusion parameter, while for the decay parameter three values are used, i.e., 0.0001,0.001 and 0.01. |
本系統中英文摘要資訊取自各篇刊載內容。