為了瞭解扶壁在開挖工程對連續壁體變位的影響，本研究利用三向度有限元素軟體PLAXIS 3D(2013)進行模擬分析；首先分析兩實際開挖案例，分別為公園2001案和金山南路案。公園2001案採用T型扶壁設計且開挖深度為8.6公尺，地層主要為軟弱黏土組成；金山南路案採用I型扶壁設計，開挖深度為26.45公尺，此基地主要地層特性為砂質土。藉由上述實際案例進行回饋分析，並依據現場監測值驗證其分析合理性，爾後遂利用相同分析手法進行案例模擬與討論。由於上述兩案例開挖特性迥異，扶壁對連續壁變位的影響並不相同，本研究藉由探討扶壁機制進而了解其影響原因。
研究結果顯示，I型扶壁抵抗連續壁變位主要機制為摩擦力，若扶壁隨開挖敲除且不考慮扶壁表面磨擦，開挖面下的扶壁勁度無法抑制連續壁變形。而T型扶壁抵抗連續壁變位的主要機制除了腹板結構與土壤的摩擦力以外，翼板結構承受的土壤承載力也是主要的原因之一。
針對參數研究，鄧文賓(2013)假設一深開挖案例，對I型扶壁行為進行討論；為了讓此假設案例臻於完整，本研究假設相同開挖案例於淺開挖進行分析，並補足其研究。研究結果顯示，若扶壁隨開挖敲除，增加扶壁勁度(厚度)並無法有效抑制連續壁變形；若扶壁不隨開挖敲除，增加扶壁勁度(厚度)即可抑制連續壁變形。

Buttress walls are a common construction method in Taiwan for protection of adjacent buildings during excavation. But the design methodologies for buttress wall is still highly empirical, in order to fully understand the mechanism and efficiency of the buttress wall, it is necessary to perform investigation.
This study will perform two excavation cases and compare the results with field measurement to ensure the correctness of input parameters. The mechanisms of I-shape and T-shape buttress wall should be studied. For I-shape buttress wall, the efficiency of reducing wall deflection will increase with length of buttress wall extending due to the frictional resistance. For T-shape buttress wall, the web structure will provide frictional resistance and the flange structure will sustain the bearing capacity, and those can support the wall deflection.
For parametric study, Deng’s (2013) research which changed length and thickness of I-shape buttress wall in deep excavation to study the effect on the wall deflection. This study will perform parametric study for shallow excavation. As I-shape buttress wall was demolished during excavation without frictional resistance on the buttress wall in the analysis, the stiffness of buttress wall cannot reduce the wall deflection. On the other hand, if the buttress wall was not demolished during excavation, the results showed that not only frictional resistance acting on the web but also the stiffness of buttress wall can reduce the wall deflection.

1. 鄧建剛(1985)，「有限元素法於台北市支撐開挖工程之應用研究」，碩士論文，國立台灣工業技術學院工程技術研究所，台北。
2. 謝百鈎(1993)，「考慮異向性行為之有限元素法深開挖分析」，碩士論文，國立台灣工業技術學院工程技術研究所，台北。
3. ACI committee 318, Building Code Requirements for Structural Concrete, (ACI 318-95) & Commentary (ACI 318R-95) (1995).
4. Clough, G.W. and O'Rourke, T.D. (1990). Construction induced movements of in-situ walls, Proceeding, design and performance of earth retaining structure, ASCE, Special Conference, Ithaca, New Yark, 439-470.
5. Calvello, M. and Finno, R. (2004). Selecting parameters to optimize in model calibration by inverse analysis, Computers and Geotechnics, Vol. 31, 410-424.
6. Deng, W.B. (2013). The Effects of Buttress Walls on Wall Deflection in Deep Excavations, Master’s Thesis, Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
7. Hsieh, P.G. (1999). Prediction of Ground Movements Caused by Deep Excavation in Clay, Ph.D. Thesis, Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
8. Hsieh, H.S. and Lu, F.C. (1999). A note on the analysis and design of diaphragm wall with buttress, Sino-Geotechnics, Vol. 79, 39-50.
9. Hsieh, H.S., Wu, L.H., Lin, T.M., Cherng, J.C. and Hsu, W.T. (2011). Performance of t-shaped diaphragm wall in a large scale excavation, Journal of GeoEngineering, Vol. 6, No. 3, 135-144.
10. Jaky, J. (1944). The coefficient of earth pressure at rest, Journal of the Society of Hungarian Architects and Engineers, Vol. 78, No. 22, 355-358.
11. Khoiri, M. (2013). Evaluation of Strength and Deformation Parameters of Granular Soils and its Implication for an Analysis of Deep Excavation, Ph.D. Thesis, Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
12. Khoiri, M. and Ou, C.Y. (2013). Evaluation of deformation parameter for deep excavation in sand through case histories, Computers and Geotechnics, Vol. 47, 57-67.
13. Ladd, C.C., Foote, R., Ishihara, K., Schlosser, F., and Poulous, H.G. (1977). Stress-deformation and strength characteristics, State-of-the-ART Report, Proceedings of the Ninth International Conference on Soil Mechanics and Foundation Engineering, Tokyo, Vol. 2, 421-494.
14. Lin, Y.L. (2010). The Effect of Cross Walls on the Movements of Excavations in Clay, Ph.D. Thesis, Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
15. Lim, A., Ou, C.Y. and Hsieh, P.G. (2010). Evaluation of clay constitutive models for analysis of deep excavation under undrained conditions, Journal of GeoEngineering, Vol. 5, No. 1, 9-20.
16. Ou, C.Y., Hsieh, P.G. and Chiou, D.C. (1993). Characteristics of ground surface settlement during excavation, Canadian Geotechnical Journal, Vol. 30, No. 5, 758-767.
17. Ou, C.Y. (2006). Deep Excavation: Theory and Practice, Taylor & Francis.
18. Ou, C.Y., Hsieh, P.G. and Lin, Y.L. (2006). Case record of an excavation with cross walls and buttress walls, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 1, No. 2, 79-86.
19. Ou, C.Y., Teng, F.C., Seed, R.B. and Wang, I.W. (2008). Using buttress walls to reduce excavation-induced movements, Journal of Geotechnical Engineering, ASCE, Proceedings of the Institution of Civil Engineering, 209-222.
20. Ou, C.Y., Hsieh, P.G. and Lin, Y.L. (2010). Performance of excavations with cross walls, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 137, 94-104.
21. Plaxis (2013). Three Dimensional FEM Manual.
22. Woo, S.M. and Moh, Z.C. (1990). Geotechnical characteristics of soils in Taipei Basin, Proceedings, 10th Southeast Asian Geotechnical Conference, Special Taiwan Session, Taipei, Vol. 2, 51-65.
23. Wang, I.W. (1998). A Study of Measures for Reducing Wall Deflection in Deep Excavation, Master’s Thesis, Department of Construction Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.