軟弱粘土層中水平層狀加勁砂樁承載試驗

Model Tests on Bearing Behavior of Horizontal Laminated Reinforced Sand Columns in Soft Clay

陳冠龍(Guan-Long Chen)

指導教授 ： 洪勇善

淡江大學/工學院/土木工程學系碩士班/碩士(2015年)

https://doi.org/10.6846/TKU.2015.00975

摘要

本研究針對軟弱粘土中層狀加勁砂樁的應用進行模型試驗，為使試驗符合現地真實行為，依模型相似律之因次分析，選擇適當的材料與尺寸進行試驗。試驗針對三種不同強度之加勁材料，分五層、十層與同向及交叉擺設以及不同加勁範圍之層數配置進行模型試驗。此外，也進行純粘土及未加勁砂樁的試驗，比較純粘土所提供的承載能力與未加勁以及不同加勁材強度、層數等承載能力的變化。

試驗結果顯示，當軟弱粘土層中之砂樁水平置入加勁材後，能有效提升軸向承載壓力，並將上方載重傳遞至砂樁底部。當擺設之加勁材強度大時，較密的加勁材間距可大幅提升砂樁之承壓能力。若加勁材具有較大之強度異向性，交叉擺設較同向擺設能帶來較好的效果。而不同加勁範圍方面，由試驗得知部分加勁無法達到與全段加勁相近之軸壓能力。擺設加勁材後，能束制砂樁側向腫脹程度，擺設間距較密且強度較大之加勁材，更能有效束制側向腫脹並使樁體變形更趨均勻。

關鍵字

砂樁 ； 軟弱粘土 ； 地工合成材 ； 層狀加勁 ； 模型試驗

並列摘要

This study investigates the bearing behavior of individual geosynthetic-laminated sand columns embedded in very soft clay through model tests. Similarity analysis was first executed to determine the suitable properties of the constituents used in the model test to ensure comparable behavior between the prototype-scale and model-scale geosynthetic-laminated sand columns. The model tests were conducted on three types of geosynthetics was employed to reinforce the sand columns either with 5 or 10 layers in same and cross direction of geosynthetic sheets horizontally placed in these model sand columns. Loading tests performed on soft clay, ordinary sand column (OSC) and laminated reinforced sand column (LRSC) were employed to explore the effectiveness of reinforcement and various horizontal spacing.

Experimental results showed that horizontally inserted reinforcements improve the bearing capability of the model sand columns. Using the reinforcements with high strength and smaller spacing can exhibit significant improvement in bearing capacity of sand column. Consequently, the greater amounts of stress are transmitted from the top to the bottom of the laminated reinforced sand columns, and the columns deform in a relatively uniform manner along the height of the columns. If the reinforcement has obvious anisotropic behavior on strength, then place it in cross can provide higher bearing capability. Additionally, local reinforced area in sand columns cannot obtain the close bearing capability.

並列關鍵字

Sand column ； Soft clay ； Geosynthetic ； Laminated reinforced ； Model test

參考文獻

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