| 摘要: | 順向坡滑動造成的重大損失不計其數，民國99年4月國道三號3.1k處山崩崩落、民國104年烏來忠治大規模崩塌以及民國111年11月汐止交流道走山事件等，不僅造成財產損失，亦有可能發生人員的傷亡，由此可知順向坡穩定性猶為重要。本研究結合地質模型(弱面分布)與地面模型(力學強度參數)，探討滑動機制(地工模型)受力學參數與弱面分布之影響。邊坡滑動穩定性除了以極限平衡法、二維數值模擬外，亦可透過三維數值模型分析整體邊坡穩定性，不再只是針對某一個最危險斷面進行分析；此外，大規模順向坡的滑動面，是否為既有明顯已貫通之弱面，或是位移過程坡體內部弱面貫通而形成，亦與順向坡內部之岩層弱面特性有關。
本研究以陽明交通大學陽明校區為例，以三維數值軟體（3DEC）進行順向坡穩定性模擬分析，透過LiDAR獲得研究區域之數值高程地形資料，並於3DEC中進行數值建模，再根據既有之鑽探報告、岩心資料及現地調查的方式，將簡化地質模型設定於數值模型中。隨後各地層內部建立符合岩心判釋結果之離散裂隙網路(DFN)，最後，針對不同順向坡滑動情境下之潛在滑動面進行弱面強度參數弱化(分別對岩石強度弱化10%、50%以及100%)，以了解力學參數弱化下，裂隙分布與生成之滑動面之關係。
根據數值分析結果，目前狀況下，校區整體是相當穩定的。然而，在力學強度弱化100%情形下，於各種假設之潛在滑動面情境中，位於操場與網球場處之邊坡產生較大位移量，經與現地調查進行比對，此處亦有發現些許張力裂縫，且產生位移之區域與台灣世曦提供之邊坡分析報告書中風險較高之區域部分重疊，仍須持續關注其穩定性。
;Dip slope stability analysis is extremely important due to the huge potential losses caused by dip slope sliding disasters. In this research, the geological model (i.e., weak plane distribution) with the ground model (mechanical properties of the weak planes) were assumed to explore the effect of weak plane distribution and mechanical properties on the failure mechanisms (Geotechnical Model) of dip slopes. To analyze the stability of dip slopes, besides the limit equilibrium method and two-dimensional numerical analysis (Slice method, etc.), it is also possible to adapt the 3D numerical analysis to analyze the overall stability of the slopes. In addition, typical dip slope sliding could occur along a given sliding plane. However, based on rock core information and boring logs, various fissures in a thick rock layer that are parallel to the potential sliding plane may be connected and form a potential sliding plane in the sliding mass.
In this research, we take the dip slope in Yang-Ming campus of National Yang-Ming Chiao Tung University as an example, and the three-dimensional distinct analysis software 3DEC was employed to analyze the overall stability of the dip slope. First of all, the 3D numerical models were generated with the digital elevation model (DEM) derived by LiDAR. Secondly, the simplified geological model with the discrete fracture network (DFN) was established in the numerical model based on the boring logs, rock core information, and field survey. Finally, various sliding scenarios corresponding to different potential sliding planes with different strength parameters were analyzed (weakening with ratios of 10%, 50%, and 100%, respectively).
Numerical analysis results show that the dip slope is relatively stable under the current situation. However, if the mechanical strength weakened up to 100%, the slope at the playground and tennis court produces larger displacement in all of the potential sliding scenarios. When comparing with the field investigation information, some tension cracks were also found here, and the area where the displacement occurred partially overlaps with the area with a higher risk in the slope analysis report provided by CECI. Hence, the dip slope may require more monitoring systems, especially for high-risk areas. |
