目前的設計中透水能力與開孔徑，皆是對未受力之織物進行量測，但埋置在土體中 的織物可能因受力而發生拉伸(張應變)，申請人的前期研究與文獻資料皆顯示，織物的 過濾特性(如透水能力、開孔徑、阻塞潛能)因張應變的發生而產生變化，經由對織物受 張後的過濾特性的探討與分析，將有助於現有設計準則的檢討與修正，確保濾材選擇的 成功。 本研究對織物於未伸張及受不同程度的張應變下，進行透水率量測、開孔徑量測， 並以改良之坡降比試驗儀，以連續變換水力坡降進行土壤-織物系統之坡降比試驗。選 用6 種針軋不織布、4 種熱熔不織布及4 種織布；單向拉伸應變為2%、5%、10％、20 ％；雙向拉伸試驗則對側向拉伸為2%、5%、10%的試體，進行正向2%、5%、10%、20% 應變的拉伸後固定，進行系列試驗。 本研究的特點為以同一拉伸後固定的試體進行 3 種試驗，因此可降低織物的不均質 對試驗結果的影響；以顯微觀察織物纖維的微觀變化，得以探討張應變造成開孔徑變化 的原因；最大拉伸應變量設定在較大值(20%)，得以涵蓋工程應用下織物受力變形範圍； 同一織法以不同厚薄材料進行試驗，其結果將能用以得到量化的關係。 The geotextiles used in filtration applications are required to meet several important objectives. Geotextile pores must be small enough to retain a significant amount of soil particles and thus prevent piping, whereas the permeability criterion requires larger pore sizes to ensure adequate water discharge. These two criteria often contradict the geotextile pore size choice. Moreover, geotextile selections based on these two criteria have not proven entirely satisfactory. Clogging or blinding may occur despite satisfactory design criteria. The design criteria or selection of suitable geotextiles involves determining the pore size and permeability of the plain geotextile and clogging potential evaluation for a soil-geotextile system. Methods to determine the filtration characteristics are carried out while the geotextile is unstrained. In many engineering applications geosynthetics are subjected to various degrees of in-plane stress/strain. The success of the aforementioned applications relies on the retention and permeability capabilities of the geotextiles and prevention of undue clogging, while geotextiles are subjected to in-plane stress/strain. The influences of axial tensile strain (uniaxial and biaxial) on the filtration characteristics of geotextiles will be studied using experimental tests. Experimental apparatus will be designed and built to carry out a series of laboratory tests. These tests included pore size distribution, flow rate measurements through plain geotextiles and gradient ratio tests. Geotextiles, nonwoven and woven, will be employed in this study. Throughout the test series, the geotextiles are stretched to various in-plane axial strains. The strained specimen test results will be compared with those from unstrained specimens. The experimental results will be used to assess the effect of tensile stress to the following filtration characteristics: pore size distribution, apparent opening size and flow rate of water through plane geotextile, and gradient ratio and discharge flow of the soil-geotextile system.