水泥系複合土壓密性質之探討

A Study of Consolidation Properties of Soil-Cementitious Materials

李嘉益(Jia-Yih Lee)

指導教授 ： 馮道偉

中原大學/工學院/土木工程研究所/碩士(2001年)

https://doi.org/10.6840/cycu200100191

摘要

台灣地狹人稠，可利用之土地日益減少，為能於高含水量及低承載力的軟弱地盤上構築結構物，地盤改良扮演著極重要角色，而深層攪拌工法為常用之地盤改良工法，其利用生石灰或水泥與土壤拌合後所產生之物理化學反應，達到土壤改良之目的。此外，政府為延續水庫的使用壽命，定期浚挖水庫的淤積淤泥，若能增加淤泥之剪力強度並降低其壓縮性，不僅能妥善處置廢棄淤泥，更可將改良過之淤泥運用為工程材料。
深層攪拌工法於工程上的應用，大部份不是做全區改良，而是於改良區域內以局部拌合的方式進行改良，未拌合處土壤可能會因擴散作用而具某種程度之改良。為瞭解石門淤泥及高嶺土經固化材均勻拌合後之壓密行為，以及以水泥局部拌合後之石門淤泥之壓密行為，本研究將壓密試驗規劃為三種類型，一是固化材均勻拌合土的壓密試驗，有石門淤泥加水泥、石門淤泥加生石灰、高嶺土加水泥及高嶺土加生石灰均勻攪拌四種；一是不同拌合形狀的局部拌合土樣壓密試驗，以6%水泥與石門淤泥局部拌合；另一則是以石門淤泥為試驗土樣，並以10%水泥將淤泥局部拌合成淤泥－水泥複合柱體，再探討未經水泥拌合之淤泥受擴散作用影響後的壓密試驗。
試驗結果顯示，不同拌合形狀的局部拌合土因不同的拌合方式而具不同的改良預壓密應力及改良效果。探討擴散影響的壓密試驗顯示，120天的擴散時間，可能已足夠使未拌合土樣受到擴散作用的影響，因其Cα/Cc值有明顯的下降，由0.032下降至0.024。對於固化材均勻拌合土樣方面，若以預壓密應力大小來評定改良成效，以水泥之改良效果較生石灰佳，且生石灰拌合土樣需長期養治才能發展出預壓密應力。另外，試驗結果亦發現，固化材拌合土樣之滲透性隨養治時間的增加而降低。

關鍵字

擴散 ； 局部拌合 ； 壓密

並列摘要

In Taiwan, the usable land is gradually decreasing. In order to construct structures on soft ground of high water content, ground improvements play an important role. Deep mixing method has frequently been used to improve engineering properties of the soft soils. It may be possible to strengthen the mud dredged from the reservoirs so that both disposal of the dredged mud and use of engineering materials are accomplished.

Most of deep mixing methods mix part of the ground with cementitious materials. It is possible that non-mixed soil is improved by diffusion. This investigation conducted three types of oedometer tests. One uses the quicklime and cement as the soildification agent to mix with SHI-MEN. Reservoir mud and kaolinite thoroughly. One uses SHI-MEN Reservoir mud to mix with 6% cement for six kind of patterns. Another uses SHI-MEN Reservoir mud to mix with 10% cement to form mud-cement column.

Results of the oedometer tests show that various mixing patterns give different preconsolidation pressure and various mixing methods give different degree of improvement. The results also show that the non-mixing mud may be affected by diffusion after 120 days of curing , since the Cα/Cc value decreases from 0.032 to 0.024. The improvement by using cement is better than quicklime, and the permeability of soil-cementitious materials decreases with curing time.

並列關鍵字

consolidation ； diffusion ； various mixing patterns

參考文獻

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