臺灣博碩士論文加值系統

扶壁與地中壁工法是目前常用的深開挖工程輔助措施，連續壁受到扶壁或地中壁的束制而減少側向變形量，其變形行為亦稱為三向度效應。然而，目前工程界常採用單向度彈塑性基礎梁法或二向度平面應變的方法設計連續壁，其分析程式無法考量扶壁與地中壁的三向度變形行為。因此，本研究使用兩種分析方法預測連續壁變形，其一為三維有限元素法PLAXIS 3D，可合理反應案例真實的變形行為；其二為單向度分析程式RIDO，將三向度效應考量為修正因子進行簡化分析，其簡化分析方法為：將扶壁兩側之摩擦力視為地盤改良的效應，以提升被動土壓力，使開挖側的土壤勁度增加。
本研究首先針對兩個深開挖案例進行RIDO與PLAXIS 3D分析，由現地監測值與分析結果顯示，扶壁長度過長時，簡化分析方法高估而導致牆變位過小，因此簡化分析方法必須適當修正。再根據開挖尺寸、開挖深度、扶壁配置數量、扶壁間距與扶壁長度等影響因子進行參數研究，並修正簡化分析方法。
本文提及的修正方法是藉由修正扶壁長度 (Bb) 來改善簡化分析方法，根據參數研究的結果，歸納出以下結論：一、當開挖長度大於40公尺時，建議使用圖4.11中的Bb最小邊界線，以避免低估連續壁牆變位。二、對於大開挖基地，增加扶壁長度比增加扶壁數量更能有效地抵抗連續壁牆變位。最後，RIDO程式搭配修正後的簡化分析方法，能夠避免高估連續壁牆變位的情形發生，並可合理模擬含有扶壁工法的開挖行為。

The diaphragm wall deflection can be reduced by the restraining effect from cross walls and buttress walls, the so called three-dimensional (3D) effect. Practically, the prediction of wall deflection has been frequently conducted by one-dimensional (1D) and two-dimensional (2D) analyses under plane strain condition. However, 1D and 2D analyses are inappropriate, when the 3D effect becomes significantly profound in excavation. Therefore, 1D analysis program RIDO along with a simplified approach is performed herein to capture 3D effect, considering the side-wall frictions as the effect of soil improvement to enhance the lateral passive earth pressure. In addition, PLAXIS 3D is used to validate this approach.
Two case histories were studied to verify the simplified approach in this thesis. When the Bb is getting greater, the approach underestimates the maximum wall deflection. Therefore, a parametric study was conducted to improve the simplified approach by discussing the influence factors such as excavation size and depth, buttress wall length (Bb), the number of buttress walls. From the results of the parametric study, the following conclusions can be drawn. Firstly, the corrected Bb proposed in this study was used to improve simplified approach. Secondly, when the excavation length is greater than 40 m, the minimum boundary of corrected Bb in Fig. 4.11 is suggested to use. Thirdly, increasing Bb is more effective than increasing the number of buttress wall to reduce the diaphragm wall deflection, especially for large excavation size. Lastly, the corrected approach is capable of capturing the 3D effect in excavation with buttress wall.

致謝 i
ABSTRACT ii
摘要 iii
CONTENTS iii
LIST OF FIGURES v
LIST OF TABLES viii
LIST OF SYMBOLS ix
Chapter 1 Introduction 1
1.1 Background and Motivation 1
1.2 Research objectives 1
1.3 Research outline 2
Chapter 2 Literature Review 4
2.1 Plane Strain Ratio 5
2.1.1 The definition of PSR 5
2.1.2 The PSR equation 5
2.1.3 The PSR equation with cross wall 6
2.1.4 3D effect of excavation and PSR in loose to medium dense sand 8
2.2 Excavation with two shapes of buttress wall 9
2.3 Lateral Earth Pressure Theory 10
2.3.1 Cohesive soil 10
2.3.2 Cohesionless soil 11
2.4 Diaphragm wall design considering buttress wall effect 12
2.4.1 The equivalent soil parameters in cohesive soil 13
2.4.2 The equivalent soil parameters in cohesionless soil 14
2.4.3 Incorporating 3D effect in small/medium size deep excavation 16
Chapter 3 Case Histories 30
3.1 Case A 30
3.1.1 Project overview 30
3.1.2 PLAXIS 3D simulation 31
3.1.3 RIDO simulation 32
3.1.4 Refined analysis 34
3.2 Case B 36
3.2.1 Project overview 36
3.2.2 PLAXIS 3D simulation 36
3.2.3 RIDO analysis 37
3.2.4 Refined analysis 38
Chapter 4 Parametric Study 58
4.1 Geometry Model for Parametric Analysis 58
4.1.1 Basic Setting 58
4.1.2 The Configuration of Excavation Variables 58
4.2 A Study of Soil Strength for the Simplified Approach 59
4.3 Results and Discussions 60
Chapter 5 Conclusions and Recommendations 78
5.1 Conclusions 78
REFERENCE 80
APPENDIX 83

[1] Bowles, J.E. (1996). Foundation analysis and design, 5th Edition, McGraw-Hill Book Company, New York, USA.
[2] Caquot, A. and J. Kerisel, (1948), Tables for calculation of passive pressure, active pressure and bearing capacity of foundations, Gauthier-Villars, Paris.
[3] Chi, S.Y., Chern, J.C. and Wang, C.C. (1999). ”Optimization of soil parameters for RIDO program,” Sino-Geotechnics, Vol. 75, pp.61-76.
[4] Clough, G.W., Smith, E.M., and Sweeney, B.P. (1989). “Movement control of excavation support systems by iterative design,” Current principles and practices, Foundation Engineering Congress, Vol. 2, ASCE, Reston, Va., pp.869–884.
[5] Finno, R. J., Blackburn, J. T., and Roboski, J. F. (2007). “Three-dimensional effects for supported excavations in clay,” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 133, pp.30-36.
[6] Hsieh, H.S., Cherng, J.C., Tsai, T.H. and Yang, M.J. (1996). “Practical considerations on diaphragm wall analysis,” Sino-Geotechnics, Vol. 53, pp.35-44.
[7] Hsieh, H.S. and Lu, F.C. (1999). “A note on the analysis and design of diaphragm wall with buttresses,” Sino-Geotechnics, Vol. 76, pp.39-50.
[8] Hsieh, H. S., Cherng, J. C. and Huang, H. F. (2010). “A note on the diaphragm wall design for small/medium size excavations”, Sino-Geotechnics, Vol. 123, pp.15-22.
[9] Hsieh, P.G., Lin, Y.L. and Ou, C.Y. (2010). “Three-dimensional numerical analysis and performance of deep excavation with cross walls and buttress walls,” Journal of the Chinese Institute of Civil and Hydraulic Engineering, Vol. 22, No. 1, pp.11-12.
[10] Hsieh, P.G., Ou, C.Y. and Shih, C. (2012). “A simplified plane strain analysis of lateral wall deflection for excavations with cross walls,” Canadian Geotechnical Journal, Vol. 49, pp.1134-1146.
[11] Hsieh P.G., Ou C.Y., Lin Y.L. (2013). “Three-dimensional numerical analysis of deep excavations with cross walls,” Acta Geotech, Vol. 8, pp.33–48.
[12] Hsieh, H.S., Huang, Y.H. and Kuo, T.Y. (2013). “System stiffness for deep excavation in soft clay,” Proceedings of the 15th Conference on Current Researches in Geotechnical Engineering in Taiwan.
[13] Hsieh, P.G. and Ou, C.Y. (2016). “Simplified approach to estimate the maximum wall deflection for deep excavations with cross walls in clay under the undrained condition,” Acta Geotechnica, Vol. 11, pp. 177-189.
[14] Hsieh, P.G., Ou, C.Y. and Hsieh, W.H. (2016). “Efficiency of excavations with buttress walls in reducing the deflection of the diaphragm wall,” Acta Geotech, Vol. 11, pp.1087–1102.
[15] Hsiung, B.B., Yang, K.H., Aila, W. and Hung, C. (2016). “Three-dimensional effects of a deep excavation on wall deflections in loose to medium dense sands,” Computers and Geotechnics, Vol. 80, pp.138–151.
[16] Janbu, N. (1963). “Soil compressibility as determined by oedometer and triaxial tests,” European Conference on Soil Mechanics and Foundation Engineering, Wiesbaden, Germany, Vol.1, pp.19-25.
[17] Jacky, J. (1944). “The coefficient of earth pressure at rest,” Journal of the Society of Hungarian Architects and Engineers, Vol. 8, No. 22, pp. 355-358.
[18] Khoiri, M. and Ou, C.Y. (2013). “Evaluation of deformation parameter for deep excavation in sand through case histories,” Computers and Geotechnics, Vol. 47, pp.57-67.
[19] Lee W.P. (2000). “Analysis of retaining wall deformation of deep excavation using simple beam method,” M.S. Dissertation, National Taiwan University of Science and Technology, Taipei, Taiwan.
[20] 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, TGS, Vol. 5, No. 1, 9-20.
[21] Likitlersuang, S., Surarak, C., Wanatowski, D., Oh, E., and Balasubramaniam, A. (2013). “Finite element analysis of a deep Excavation: a case study from the Bangkok MRT,” Soil and Foundations, Vol. 53, No. 5, pp.756-773.
[22] Ou, C.Y., Chiou, D.C., and Wu, T.S. (1996). “Three-dimensional finite element analysis of deep excavations,” Journal of Geotechnical Engineering, Vol. 122, No.5, pp.337-345.
[23] Ou, C.Y., and Lai, C.H. (1994). “Finite-element analysis of deep excavation in layered sandy and clayey soil deposits,” Canadian Geotechnical Journal, Vol. 31, pp.204-214.
[24] Ou C.Y. (2006). Deep excavation: theory and practice, Taylor and Francis, London.
[25] Padfield, C.J. and Mair, R.J. (1984). “Design of retaining walls embedded in stiff clay,” CIRIA Report No. 104, England, pp. 83-84.
[26] Terzaghi, K. (1955). “Evaluation of the coefficient of subgrade reactions,” Geotechnique, Vol. 5, No. 4, pp.197-226.
[27] Vesic, A.S. (1961). Beam on elastic subgrade and the Winkler’s hypothesis, 5th ICSMFE, Vol. 1, pp. 845-850