生態工程滲透陰井之保水滲透性能分析

The Experimental Analysis of Infiltration Well Using Ecological Engineering Design

由於都市生活機能完善，成為人口匯聚之地，人口集中導致都市居住用地需求急遽增加，舊都市土地一旦不敷所需，都市居民勢必向都市周圍發展，造成都市區域擴展，使得原有的溼地、水田、森林、綠地等區域也因而開始產生都市化之現象，造成城鄉水環境之丕變。台灣因都會區綠地不足與社區過度不透水化，土地喪失水之涵養力亦使得地表逕流量暴增造成水災頻傳。然而這些災難並非不可避免，山坡地社區也並非完全不可開發，只要加強建築基地保水及透水設計就可減緩其弊害。現階段我國綠建築政策對於滲透設施相關設計技術，尚處於理論假設之計算層次，本研究透過不同開孔率之滲透陰井，進行滲透性能測試，進而建立相關影響因素及試驗方法與步驟，並據以完成滲透陰井之設計保水量公式。

Urbanization reduces the opportunity of stormwater infiltration that lessens groundwater recharge and increases pollutant loads to streams. Reduction of Infiltration from impervious areas in the urban environment is one of the key issues in urban flooding; therefore, increasing the infiltration opportunity and capacity in the urban environment can be a good option to tackle this problem. This study assessed the performance and developed a simple approach for estimating infiltration capacity of infiltration wells by employing on-site tests. Water infiltrated from the surfaces of three diameters (30cm, 40cm and 50cm) and five opening ratios (0.892％ , 0.783％ , 0.708％ , 0.3915％ and 0.354％ ) of infiltration wells were measured under non-flowing and steady state conditions. The results from infiltration wells test indicate that the correlations between Specific Infiltration Area ( Aus ), which is defined as the finial infiltration rate divided by saturated hydraulic conductivity of the soil (Ksat ) and the depth of water (H ) is linearly dependent on each other for three diameters and five opening ratios of infiltration wells. Experimental results also indicate that when the decrease in opening ratio of the infiltration well is 50％ , the infiltration wells still retain about 90% for infiltration capacity. Based on these results, the Aus for different H and radiuses (r ) can be obtained assuming their hydraulic conditions are similar. Those design curves developed by the study provide as the practical tools for designing infiltration wells.