| 摘要: | 臺灣西北部臺地邊緣常於豪雨後發生邊坡滑動，此一地質現象與地形、地質以及水文等因素均有密切之關連性。本文以湖口臺地南緣復發性崩塌地為案例，探討：(1)膠結不良砂泥岩互層邊坡水力傳導係數之異向性與異質性以及(2)與砂頁岩不整合接觸之臺地礫石自由含水層，分別對邊坡地下水流動之影響，以及滑動面孔隙水壓分布之影響。本研究利用有限差分法程式FLAC(Fast Lagranglan Analysis of Continua)進行地下水流動之模擬，根據鑽井岩心地質紀錄以及現地透水試驗，以建立研究區之水文地質概念模型，並藉由92年3月~94年1月之現地水壓計監測資料，校正水文地質概念模型與模式之參數。根據校正後之模型數值模擬結果，本研究以逆分析(Back analysis)以獲取湖口臺地地層滑動之相關材料參數。為瞭解水文地質因素對湖口臺地邊坡活動頻繁之影響，本研究進行參數敏感度分析與邊坡穩定正分析，以了解各項水文地質特性對滑動面上孔隙水壓以及邊坡安全係數之影響。 研究結果顯示，水力傳導係數異向性與異質性以及臺地礫石層之自由含水層，均高度影響著邊坡孔隙水壓的分佈，因而影響邊坡有效應力、抗剪強度以及安全係數。對於不整合上覆臺地礫石之更新世砂、頁岩互層邊坡，水文地質作用對於其復發式的地滑活動扮演不可忽視之影響。 The terrace of northwestern of Taiwan part often takes place slides after torrential rain. This have close connection, geological phenomenon and topography, geology, and hydrology factor. This text regards the south reason of HuKou terrace recuring collapse as the case, probe into: (1) anisotropic and heterogeneous of hydraulic conductivity of Poorly cemented and stratified sandstone, mudstone and shale , and (2) the free aquifer of terrace gravel contact sandstone, mudstone and shale, influence opposite side slope and groundwater flow, and influence that pore water pressure distributes on slip face. This research utilizes limited difference to divide the law procedure FLAC (Fast Lagranglan Analysis of Continua ) to carry on the simulation that the groundwater flowed. the In base of core noted down and the field permeability test, we set up the hydrogeological conceptual models of the studying area, and combining March of 2003 ~ January of 2005 water pressure monitors to calibrate the hydrogeological conceptual model and parameters . According to the model numerical simulation result after calibrating, we use back-analysis in order to obtain the relevant material parameter of the south reason of HuKou terrace and stratum in this research. For find out about hydrogeological factor to the south reason of HuKou terrace that takes place slides frequently, this research carry on parameter susceptibility analysis with steady to analysis in slope, in order to understand that every hydrogeological characteristic is to slipping the influence of pore water pressure and slope safety coefficient on the slip face. The result of study shows that anisotropic and heterogeneous of hydraulic conductivity and the free aquifer of gravel terrace both influence highly pore watwer pressure distribution on the slope, therefore influence the effect strength, resisting shear strength and safety factor of the slope. Slope of one layer of sides as to not exactly closing sandstone, mudstone and shale in Pleistocene covering terrace gravel each other, hydrology geologic process slippery activity act the influence that can't be ignored. |
