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    Title: 張應變對針軋不織布過濾及阻留特性的影響
    Other Titles: The influence of tensile strain on filtration and retention properties of needle-punched nonwoven geotextiles
    Authors: 許家綸;Hsu, Jia-Lun
    Contributors: 淡江大學土木工程學系碩士班
    吳朝賢;Wu, Cho-Sen
    Keywords: 針軋不織布;張應變;開孔徑;透水速率;Giroud(1996)透水經驗式;Needle-punched nonwoven geotextiles;Tensile strain;Pore size;Flow velocity;Giroud (1996) permeability experiential formul
    Date: 2013
    Issue Date: 2013-04-13 11:48:53 (UTC+8)
    Abstract: 本研究將三種不同的針軋不織布施以不同拉伸方向(機器方向、橫穿方向、雙向)與不同程度的張應變後,進行透水速率、開孔徑及厚度的量測,進而探討拉伸應變對地工不織布開孔徑及透水能力的影響,後續再根據Giroud(1996)透水經驗式去探討理論經驗式對受拉伸不織布透水性預測的適用性。
    不織布拉伸試驗結果顯示,厚度隨著拉伸應變越大而逐漸變小,在相同應變下,不織布經單向拉伸後與未拉伸時的改變量比較,為機器方向改變量比橫穿方向大;而單向比雙向拉伸所造成的改變量小;孔隙率則皆隨應變增加而增加。
    透水速率試驗結果顯示,三種不織布的透水速率皆隨張應變增加至5%而逐漸降低,但拉伸在較大應變區間(7.5%~20%)時透水速率隨應變增大而增加。在相同張應變程度的拉伸下,針軋不織布隨著厚度的增加,透水速率越慢。三種不同拉伸方式對三種不織布的透水速率的影響為,在相同應變下,不織布經單向拉伸後透水速率為機器方向比橫穿方向快,單向皆比雙向拉伸試體快。透水速率隨著拉伸應變的增加而降低後再上升,最低的透水速率都發生在5%張應變。
    不織布開孔徑量測結果顯示,三種不織布的開孔徑皆隨張應變之增加而減少,三種不同厚度及不同拉伸方式的不織布,其開孔徑分佈曲線有相似的趨勢。在相同應變下,不織布經單向拉伸後開孔徑為機器方向比橫穿方向大,而單向皆比雙向拉伸試體大。
    Giroud(1996)所提出之經驗與本研究結果相互比較結果為,當針軋不織布受張後造成孔隙率逐漸變大,孔隙率大於0.90後與經驗式之相互差異逐漸變大,其中以雙向最為明顯。本研究孔隙率計算方式為正向應力1 kPa及2 kPa下所量測之厚度,與Giroud (1996)在高正向應力下之方式不盡相同,因此造成 Giroud (1996)所提出之經驗式與本研究試驗結果之差異性。
    The influence of uniaxial (machine direction, cross direction) and biaxial tensile strain on pore size distribution, seepage rate and thickness of three needle-punched nonwoven geotextiles were investigated in this study. Geotextile thickness upon tensile strain was used to calculate geotextile porosity and to validate Giroud’s(1996)formula using for permeability evaluation.

    The geotextiles were stretched to 0%, 2%, 5%, 7.5%, 10% and 20% strains prior to installation in apparatus. The experimental results show: (1) Geotextile thickness is decreased with the increase in tensile strain. Under a specific tensile strain, tension in machine direction reduces more specimens’ thickness than cross direction dose. Furthermore, specimen subjected to biaxial tension reduces more thickness than the other two uniaxial tensions. (2) Flow rate slows down with the increase in tensile strain till 5% strain, but the trend reversed for specimen subjected to strains higher than 5%. (3) For all tested geotextiles, opening sizes (O95,O85,O50) are reduced with increasing tensile strain. All tested specimens have similar tendency in their pore size distribution curves. (4) For geotextile subjected to tensile strain, Giroud’s equation can not predict geotextile permeability properly.
    Appears in Collections:[土木工程學系暨研究所] 學位論文

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