碩士 / 國立臺灣大學 / 土木工程學研究所 / 91 / The purpose of this excerpt is to build up a method, it can be used for parameter identification of confined or unconfined aquifer which the area is by the sea . The excerpt presume that the aquifer and the coastline is contact by vertical , it also doesn’t need to consider the difference of seawater and fresh water of the specific gravity and presume the surface of seawater and fresh water is a vertical surface .
The method of parameter identification of this excerpt can be divide into two phases, the first phase is to use the tided observation watermark and the observation watermark of observation well by Fourier spectrum to get the tides efficiency and delayed time under the condition of no pumping water, then use the analytical solution of Ferris(1951) to get the speculated values of parameter ratio, put this data into the optimal mode to proceed the parameter examination. For confined aquifer, we can find out the ratio(S/T) of real reserve water parameter and circulate parameter. For unconfined aquifer, we can not only find out the ratio of specific and hydraulic power conducted coefficient but also get the thickness b from sea surface to the bottom of aquifer; The second phase is to utilize the results from the first phase and the watermark observation data of the pumping water test then we put this data into the optimal mode to get individual parameter values. The parameter examine optimal mode of objective functions of this excerpt are the most small square sum of difference between observed watermark and calculated watermark, the limited form is a control formula for counting water table, it is a non-linear question because of optimal mode problem. This excerpt is utilize the BFGS method to co-operate with the influence-coefficient-method to find out the searching direction from parameter examination, and use the principle of approximately quadratic curve to get optimal movable step-size for counting the correction of parameter in every iteration until the objective function became to be the most small value.
The limit forms of parameter examination optimal mode in this excerpt are all groundwater flow control formula. The process of solving the confined aquifer’s water flow controlling formula, we utilize Ferris(1951) to conduct the analytical solution of watermark which the aquifer is by the sea and combine with the Theis method and image well to get the original formula’s analytical solution, but when we are in the process of solving the unconfined aquifer’s water flow controlling formula, we adopt the limited differential method and Full implicit method to establish a value mode then we can use iteration method to solve it.
In order to manifest this method is usability, we utilize a fictitious system of aquifer by the sea to be used for the designed two phases parameter examination of this article, as the study result reveal, when observation data didn’t influence by disturbed under the condition of no pumping water at first phase, we not only can examine the truth value of confined aquifer’s parameter ratio(S/T) by tides and water table observing data, but also can examine the truth value of unconfined aquifer’s parameter ratio(Sy/K) and thickness b from sea surface to the bottom of aquifer; Under the condition of pumping water at second phase, we can examine the truth value of individual parameter(S&T and Sy&K). In order to suit for real condition, this excerpt also consider the situation that the observing data was influence by disturbed, as the result reveal, the more noise we did, the bigger value we got when we examine the difference of parameter and real parameter value. In order not to influence the result of second parameter identification from the incorrect outcome of first parameter identification, this research is trying to prove the suitability of “two-steps parameter identifications method” with the way of examining parameters at the same time. The result of this research shows that “two-steps parameter identifications method” is feasible.
| Identifer | oai:union.ndltd.org:TW/091NTU00015028 |
| Date | January 2003 |
| Creators | Chia-Cheng Li, 李家彰 |
| Contributors | Nien-Sheng Hsu, 徐年盛 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 0 |
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