集集地震引起濁水溪沖積扇水文及水文地質變化之解析與地質統計分析

Deterministic and geostatistical analysis of the hydrological and hydrogeological changes associated with the ChiChi earthquake in the ChouShui River alluvial fan

林允斌(Yun-Bin Lin)

指導教授 ： 譚義績

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/博士(2004年)

https://doi.org/10.6342/NTU.2004.02191

摘要

本研究第一部份為解析分析，藉由發展一個黏彈性模式用以模擬台灣地區濁水溪沖積扇地下水水位於集集地震後之水位變化，在假設拘限含水層於共震期間無滲流之情況下，求得模式之解析解，該解析解應用於分析設置在濁水溪沖積扇上高密度之地下水位觀測站網所蒐集到的資料，模擬的結果與現地觀測值十分吻合，模式的黏滯係數與含水層之水利傳導係數有高度相關性，同時經由模擬發現，含水層水文地質非均勻性構造對於濁水溪沖積扇於地震後之地下水位變化與土壤液化之位置具有決定性之影響，此外，更進一步探討利用地震引起之地下水位變化推測地下水文地質分均勻性現象之可能性。
本研究第二部分為地質統計分析，首次利用一般克利金法、連續高斯模擬法及褪火演算法處理地下水觀測站網與標準衛星控制點系統兩站網所蒐集到完全異位性資料之問題，並利用因子克利金法分析並繪製兩站網七個變數間之關係圖，其中七個變數包含三個含水層的水文傳導係數、三個含水層於地震後地下水水位變化及地表之垂直位移，本研究並描述因芮氏強度7.3級之集集地震所導致空間上水文地質於不同尺度下之異常變化，研究顯示，地震所引起的水文地質變化可分為三個尺度，分別為影響距離為9公里的微尺度、12公里的中尺度及36公里的大尺度，進一步利用因子克利金分析法之成分分析求得，微尺度下地下水文之空間變化主要受孔隙壓所之影響，中尺度下主要為含水層非均勻沉積物之影響，而大尺度下則取決於反覆作用之剪應力，此外，大尺度之區域化因子亦充分顯示因地震所導致沖積扇中水文地質特性的變化特性。

關鍵字

集集地震 ； 解析解 ； 地下水文 ； 水文地質 ； 地理統計

並列摘要

This thesis includes two parts concerning the deterministic and the geostatistical analysis of the hydrological and the hydrogeological changes associated with the ChiChi earthquake in the ChouShui river alluvial fan.
In the deterministic analysis, a visco-elastic model is developed to simulate the groundwater level changes in the Cho-Shui River alluvial fan in Taiwan after the Chi-Chi earthquake. An analytical solution is derived with the assumption that no leakage occurred in confined aquifers during the co-seismic period. The solution is used to analyze the data collected from a high-density network of hydrologic monitoring wells in the Cho-Shui River alluvial fan. The simulated groundwater level changes agree with the observations. The viscosity coefficient of the model was found to correlate with the hydraulic conductivity of the aquifer. The field observations and the simulations reveal the influence of geological structures and heterogeneity on the groundwater changes and locations of sediment liquefactions in the alluvial fan during the Chi-Chi earthquake. Possible applications to imaging subsurface hydraulic heterogeneity are discussed using information about groundwater level changes induced by earthquakes.
Due to over simplified assumptions for determining the analytical solution of the former deterministic relation, the geostatistical method is then used to investigate the statistical significant of the mechanics, concerning the inhomogeneous strata of the aquifers, adopted in developing the deterministic relation and fitting the analytical solution. The causes of the spatial variations of groundwater hydrological changes at different scales are also discussed.
In the geostatistical analysis, Ordinary Kriging (OK), Sequential Gaussian Simulation (SGS) and Simulated Annealing Simulation (SAS) are used to relocate the completely heterotopic dataset from the locations of the Standardized Satellite Oriented Control Point System (SSOCPS) stations to the Groundwater Monitoring Networks (GMNS) stations and factorial kriging to analyze and map relationships among seven variables, including the hydraulic conductivities of three aquifers, the vertical displacements of the ground and groundwater level changes in the wells of three aquifers, and also to delineate the anomalies of multi-scale spatial variation of hydrogeological properties associated with the ChiChi earthquake, measuring 7.3 on the Richter scale, in the ChouShui River alluvial fan in Taiwan. In this study, the anomalies of spatial variation of hydrogeological properties associated with the earthquake are illustrated at micro, local and regional scales of 9, 12 and 36 km, respectively. In the study area, regionalization components associated with variation at local and regional scales are obtained and mapped by factorial kriging. Factorial Kriging Analysis (FKA) also demonstrated that the main effects of the ChiChi earthquake on the spatial variations of groundwater hydrological changes include porous media compression at micro scale, hydrogeological heterogeneousness of the sediments within the aquifer at local scale and the cyclic loading of deviatoric stress at regional scale. Finally, maps of spatial variations of regional components fully depicted all of the anomalies of spatial variation of hydrogeological changes due to the ChiChi earthquake and can be used to identify, confirm and monitor the hydrogeological properties in this study area.

並列關鍵字

Hydrogeology ； Deterministic solution ； ChiChi earthquake ； Groundwater hydrology ； Geostatistics

參考文獻

Almeida, A., and A. Journel, Joint simulation of multiple variables with Markov-type coregionalization model, Mathematical Geology, 26, 565-588, 1994.

Anderson, T. W., An introduction to multivariate statistical analysis, John Wiley & Sons, New York, 1984.

Bardet, J. P., A viscoelastic model for the dynamics behavior of saturated pore-elastic solids, Journal of Applied Mechanics, 59, 128-135, 1992.

Berryman, J. G., L. Thigpen, and C. T. Chin, Bulk elastic wave propagation in partially saturated porous solids, The Journal of the Acoustical Society of America; 4, 360-373, 1988.

Biot, M. A., Theory of propagation of elastic waves in a fluid-saturated porous solid, I. low-frequency range, The Journal of the Acoustical Society of America, 28, 168-178, 1956a.