為了探討南市172線42k+300處邊坡在不同降雨強度下的三維邊坡穩定分析，本研究使用GMS (Groundwater Modeling System)建立研究區域的三維地質模型及三種不同時間點之地下水位面，並以2022年4月地下水位面進行三種不同降雨強度的降雨入滲模擬，進而探討此邊坡之穩定性。此外，本研究使用FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions)中內建的FISH語言編寫飽和-不飽和滲流場模型，透過基質吸力的變化去修正不飽和土壤的滲透係數與有效應力場，模擬不飽和降雨入滲行為，本研究以SCS曲線號碼法(Soil Conservation Service Curve Number)設計邊坡的有效降雨量，以2022年4月水位面作為初始水位進行三種不同降雨強度(100、200、350 mm/day)模擬，進而探討其三維邊坡穩定分析。並將此區域內的民間顧問公司監測資料與本研究模擬結果進行比較，檢視兩者間的吻合度，以此驗證模型的可靠性。
三種不同時間點水位的模擬結果顯示：2022年1月水位的民宅區域安全係數約為1.5~1.55，4月水位的民宅區域安全係數約為1.45~1.55，而7月水位的民宅區域安全係數約為1.40~1.50，其最大剪應變率隨著地下水位面上升逐漸提高。而三種不同降雨強度入滲的模擬結果顯示水位約上升0.20~2.06 m，入滲將造成局部不飽和帶的變化與整體水位抬升，使有效應力和剪力強度下降，而造成整體安全係數的降低。

To discuss the stability of the slope at 42k+300 of County Highway 172 in Tainan City under different rainfall intensities, a three-dimensional geologic model of the study area and groundwater levels at three different time points were developed using the GMS (Groundwater Modeling System), and rainfall infiltration simulations with three different rainfall intensities were carried out on the groundwater level in April 2022 to investigate the stability of this slope. In addition, three different rainfall intensities were used to simulate the rainfall infiltration at the groundwater table in April 2022 to investigate the stability of the slope.
In this study, the effective rainfall on the slope was designed by the SCS curve number method (Soil Conservation Service Curve Number), and three-dimensional slope stability analysus were conducted with three different rainfall intensities. The reliability of the model was verified by comparing the monitoring data of civil consultants in the region with the simulation results of this study to check the agreement between the two.
The simulation results of the water level at three different time points show that in 2022, the coefficient of safety of the residential area at the January water level is about 1.5~1.55, the coefficient of safety of the residential area at the April water level is about 1.45~1.55, and the coefficient of safety of the residential area at the July water level is about 1.40~1.50, whose maximum shear strain variability is gradually increasing along with the increase of the groundwater table surface. The simulation results for the three different rainfall intensities show that the water level rises by about 0.20 to 2.06 m. The increase in water level leads to a decrease in the overall safety coefficient.

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