暴雨期間之降雨所形成的地表水經入滲後，造成表土層內部孔隙水壓增加，此為造成邊坡淺層破壞之主要原因之一。本研究主要探討降雨入滲行為，採用圓型砂柱設備利用Green-Ampt(1911)入滲公式與李(2003)降雨入滲造成濕鋒線以上孔隙水壓變化之觀念為基礎理論，探討入滲效應之行為機制。實驗以均勻級配之砂土，於不同土體孔隙率與不同定積水深度下進行討論。 實驗結果顯示較大之土體孔隙率與定積水深度皆會造成較快之入滲率；入滲濕鋒之吸力水頭值會隨著入滲時間以及積水深度增加而有逐漸增大之趨勢；當積水深度越大時，濕鋒線以上之孔隙水壓有非線性分佈之趨勢；入滲濕鋒隨著時間增加，則有越不飽和之情形等。 此外，運用Green-Ampt(1911)、Brakenseik(1977)、Wang and Benson(1995)、Kao and Hunt(1996)以及李(2003)之理論式與實驗數據比較，發現Green-Ampt最能模擬實際入滲率之情形；濕鋒線以上之孔隙水壓分佈則以李(2003)之理論式有最佳模擬結果。未來，期望運用本研究結果，探討降雨入滲造成濕鋒線以上孔隙水壓變化對淺層崩塌之影響機制。 The infiltration of the surface-water increases the seepage force and the pore water pressure, and causes the failure of the shllow-layer slopes. The purpose of this study is to examine the unsaturated shallow slope failures triggered by infiltration from the Soil Column Apparatus (S.C.A. henceforth) exposure and verification. This study takes account of experimental tests and theory verification (Green-Ampt, 1911, and Lee, 2003) to analysis pore water pressure varying with the wetting front downward.The experimental results demonstrate that the variations of the infiltration capacity were influenced by porosity and the depth of ponding water. The value of suction head at wetting front is increase the increasing of the infiltration time and the depth of the constant water depth. Furthermore, the value of pore water pressure above wetting front trend to nonlinear variation as increasing the depth of ponding water and increasing the elapsed time. Moreover, employing Green-Ampt model(1911)、Brakenseik model(1977)、Wang and Benson model(1995)、Kao and Hunt model(1996) and Lee model(2003) compare with the experimental data, the Green-Ampt model is most agreement with infiltration data , and the Lee model is best fit to variation of pore pressure above the wetting front. In the future, by employing experimental results, it expects to understand the shallow failure related to the variation of the pore water pressure caused by the rainfall infiltration.
