地工蜂巢格網加勁於砂土路基之承載能力研究

A Study of Bearing Capacity for Geocell Reinforcement on Sand Subgrade

張家豪(Chia-Hao Chang)

指導教授 ： 張達德

中原大學/工學院/土木工程研究所/碩士(2004年)

https://doi.org/10.6840/cycu200400522

摘要

加勁土壤由於施工快速、造價低廉及吸能耐震等優點，目前已廣泛應用於大地工程中。而地工蜂巢格網為新興之地工合成材，於國內仍較少被使用，本研究目的即是希望能透過此一研究，對地工蜂巢格網之承載作用機制進行更詳盡之探討，以回饋現地加勁土壤之設計應用。

本研究擬以自行規劃之平鈑載重試驗設備，其試驗槽尺寸為(H)60cm×(W)90cm×(L)150cm，配合兩種不同高度蜂巢格與兩種不同尺寸之圓形平鈑 (直徑20cm、30cm)，以砂土作為介質進行研究。藉由電子式位移計(LVDT)以精確量測平鈑沉陷行為，觀測試驗過程並分析試驗結果以了解其作用機制。

根據研究成果指出，承載阻抗之發展可分成三階段，第一階段為摩擦阻抗發展期、第二階段為蜂巢格網受力伸張發展期、第三階段為土壤達到塑性期。與未加勁砂土進行比對，蜂巢格網發揮良好之加勁效果，於承載能力提升約有1.4倍，並有效減少沉陷量之產生；而承載能力也隨著地工蜂巢格網高度增加而提升，沉陷量也隨之減少。由研究發現，地工蜂巢格網加勁於載重過程破壞後，仍然具有相當之加勁成效。不論由承載比、地盤反力係數來看，都顯示出地工蜂巢格網之承載能力會隨其高度增加而增加之關係。

關鍵字

加勁土壤 ； 地工蜂巢格網 ； 承載能力 ； 平鈑載重試驗

並列摘要

The advantages of geocells in reinforcement of earth material have been applied broadly in geotechnical engineering. Geocell is newly risen geosynthetics that unusually be used in Taiwan. The objective of this dissertation study aims to present braring behavior and interaction mechanism of geocells for the future applications.

In this study, a custom-made, load plate testing device, with a size of (H)60cm×(W)90cm×(L)150cm is used. The study uses sandy soil to fit two types of geocells those different heights and two types of circle plate those different sizes (diameter, 20cm/30cm). Then we can measure the behavior of plate sediments precisely using four LVDT. Observing and analyzing test results, the mechanisms were determined.

According to the results of this study, the development of bearing resistance can be categorized in the following three stages： (1) The period of frictional resistance development. (2) The period of development that geocells is applied tension. (3)The period of soil mass is up to plasticity. It is compared with unreinforcement of earth material, geocells make the reinforcement well. It utilizes about 1.4 times in bearing capacity and decreases the occurrence of sediments very well. Bearing capacity increases with the heights of geocells and sediments decreases with the heights of geocells. In the results, we can discover that after geocells are failure in the procession of load, it still has the ability of reinforcement. It always shows that bearing capacity increases with the heights of geocells whatever in bearing capacity ratio (BCR) or coefficient of subgrade reaction (k).

並列關鍵字

earth reinforcement ； load-plate test ； bearing ； geocell

參考文獻

6.王聖昌，“地工合成材料於鐵路湧泥改善之研究”，碩士論文，國立成功大學土木工程研究所 (2003)。

11.Braja M. Das, “Principles of Foundation Engineering”, 3th Editon, 1996.

12.Mandal, J.N. and Sah, H.S., ” Bearing Capacity Texts on Geogrid- Reinforced Clay, ” Geotextiles and Geomembrances, 1992.

14.Mhaiskar, S.Y. (I.I.T); Mandal, J.N. “Soft clay subgrade stabilisation using geocells”, Geotechnical Special Publication, v 2, n 30, 1992, p 1092-1103.

15.Dash, S.K. Rajagopal, K. Krishnaswamy, N.R. “Strip footing on geocell reinforced sand beds with additional planar reinforcement”, Geotextiles and Geomembranes, v 19, n 8, December, 2001, p 529-538