軟弱黏土中層狀加勁砂柱承載行為之數值模擬

淡江大學機構典藏 > 工學院 > 土木工程學系暨研究所 > 學位論文 > Item 987654321/114596

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题名:	軟弱黏土中層狀加勁砂柱承載行為之數值模擬
其它题名:	Numerical analysis of geosynthetic-laminated sand columns under vertical loading in soft clay
作者:	林明瑋;Lin, Ming-Wei
贡献者:	淡江大學土木工程學系碩士班吳朝賢;Wu, Cho-Sen
关键词:	砂石樁;層狀加勁;加勁材;軟弱黏土;數值模擬;承載力;sand column;Laminated;Soft clay;numerical modeling;bearing capacity
日期:	2017
上传时间:	2018-08-03 14:57:45 (UTC+8)
摘要:	本研究利用有限差分軟體FLAC撰寫數值分析程式，藉由分析結果探討軟弱黏土中層狀加勁砂柱之力學行為，由模型試驗為基準，驗證數值分析之正確性，而後建立現場軟弱填土中層狀加勁砂石樁數值模型，依據影響層狀加勁砂石樁承載行為之重要參數，如加勁材勁度、間距比S/D、加勁範圍Lr/L及樁徑，進行實體砂石樁之參數研究，剖析加載過程中樁體變形、黏土側向壓力與加勁材受力情形等，並以砂土內部最小主應力分佈為基準，加以分析加勁材於砂石樁內之影響範圍。由研究結果分析可得，加勁材之勁度對於樁體變形以及黏土提供之側向壓力，並無顯著之影響，其加勁提升效果會依間距比不同而有所不同，當間距比愈小時提升效果較愈加。當間距比為1.0、0.5以及0.25時，其加勁深度只需3 m、5 m以及8 m即可與全段加勁效果相同，若低於各臨界加勁深度其承載力將小於全段加勁。由加勁砂石樁砂土最小主應力分佈情形，可知其軸心受到加勁材影響最大，由軸心向外圍遞減，但遞減範圍依間距比不同而有所差異。當間距比為1.0時其內部砂土受加勁材影響範圍有限，故於加勁材勁度不同時其提升效果較差。當間距比為0.25時其內部砂土受加勁材影響範圍為全段，故於加勁材勁度不同時其提升較佳，結果可得加勁材之勁度對其影響範圍內產生作用，對於加勁範圍影響較小，加勁材勁度越高，對砂土束制力較強，對其加勁範圍內的圍壓增量提升最高，能夠達到最有效加勁效果。 The purpose of this study is to investigate the mechanical behavior of geosynthetic-laminated sand columns embedded in soft clay using the finite difference software FLAC. Numerical analysis results are verified by laboratory test results. Based on the important parameters affecting the behavior of the laminated column, reinforcement stiffness, S/D ratio, reinforced length ratio and column diameter are chosen to investigate the mechanical behavior of sand columns in this study. The influence of laminated reinforcement in terms of column deformation, later pressure of the clay and the circumferential tensile stress of the geotextiles during the loading process are investigated. The results of the analysis show that: (1) Reinforcement stiffness has insignificant effect on the deformation of the column and the later pressure of the clay, (2) The effect of reinforcement stiffness varies with the S/D ratio, reinforcement is more effective for column with smaller S/D ratio, (3) For columns with S/D=1.0, 0.5, and 0.25, the columns have reinforced depth of 3 m, 5 m and 8 m, respectively produce the same vertical loading as the fully reinforced column, (4) According to the distribution of the minor principal stress in sand column, the contribution in providing confining stress of the laminated reinforcement decrease from the axis to the periphery; the degree of variation varies with S/D ratio, (5) The influence area of the sand by the reinforcement depends on the S/D ratio only, however, reinforcement stiffness affects the magnitude of the stress.
显示于类别:	[土木工程學系暨研究所] 學位論文

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