為了探討地盤改良對軟弱黏土層中進行島區式開挖行為之影響，本研究透過1-g的超軟黏土模型試驗，以及三维有限差分程式(FLAC3D)之數值分析，來評估不同條件下地盤改良對黏土層島區式開挖之影響，並與實際工程案例比較，以探討地盤改良在島區式開挖工法之應用。研究結果顯示塊狀地盤改良減少地表沉陷之效果最佳，壁狀改良次之，柱狀改良更次之；地盤改良之寬度應達擋土壁之被動破壞面以外，且改良強度足夠時，才能提供相當程度之阻抗力。當島區式開挖之整體滑動安全係數大於1.4(穩定數Nb低於臨界穩定數Ncb)時，大致屬於位移量不大之穩定狀況，地盤改良可適度發揮其減低土壤位移之效果。若以改良土及未改良土之壓縮強度來表示經柱狀地盤改良複合土體之異向性強度，研究結果顯示改良土強度之折減高達70~85%；此外，當整體滑動安全係數小於1.2(穩定數Nb高於臨界穩定數Ncb)時，地盤改良所減少地表沉陷，依土戧尺寸(土戧邊坡坡度)及改良率之不同，而有大幅度之變化，屬於較不穩定之狀態。若土戧之尺寸夠大(即坡度較緩時)，則於土戧內部進行足夠之柱狀地盤改良，可增加開挖穩定性並大幅減少位移；而若土戧之尺寸較小(即坡度較陡時)，即便在土戧內部進行高改良率之柱狀改良，開挖造成之土壤位移仍將偏大，但尚可維持土戧複合土體之穩定及整體島區式開挖之安全。

To evaluate the effect of ground improvement on the behavior of bermed excavation in clay, a 1-g model test using the extremely soft clay was proposed here. In addition, the numerical analyses using a three-dimensional explicit finite difference program (FLAC3D) are also performed for comparing the surface settlement associated with different ground improvement layouts in the field. Also, two field observation cases are compared with the numerical analysis results to evaluate the results generated from the model study. Test and analysis results had indicated that the buttress type arrangement has a better effect on controlling the bermed excavation induced surface settlement than the column type arrangement. Moreover, it has been found that it is more effective to reduce the soil movement when the improved zone has enough strength and the dimension of improvement extends beyond the passive failure zone of the retaining wall. When the safety factor of global sliding stability of bermed excavation is lager than 1.4, the reductions in ground settlement for various ground improvement layouts are only fractional. Under this condition, the ground improvement inside the berm can more effectively reduce the soil movement caused by bermed excavation. However, when the safety factor of global sliding stability is less than 1.2, the reduction of ground settlement varies in a wider range. In summary, if the berm size is large and with sufficient ground improvement, the stability of excavation is high and can reduce a lot of soil movement. In contrast, if the berm size is small and safety factor against global sliding is low, then the soil movement will be large. But with high improvement ratio in the berm, the stability of berm can be maintained. So the ground improvement can play a role in reduction the excavation induced ground movement.

1、 大地工程學會（1998），建築技術規則建築構造編—基礎構造設計規範。
2、 王建智（1997），「深開挖引致之軟弱黏土不排水潛變行為之研究」，博士論文，國立台灣科技大學營建工程研究所。
3、 王建智（2001），「應用FLAC程式進行深開挖分析之方法與實例」，中英深開挖工程及結構物耐震設計研討會。
4、 石正義譯 (1992)，「鑚探圖的判讀要領」，詹氏書局出版。
5、 李崇正、林志棟、林俊雄（1994），「大地工程研究者之新工具:離心模型試驗」，岩盤工程研討會論文集，中壢，第649~669頁。
6、 周功台、趙基盛（1987），「擋土牆型式之選擇與設計之考慮」，地工技術雜誌，第17期，第15-22頁。
7、 吳宗憲（1994），「柱狀地盤改良應用於深開挖之分析研究」，國立台灣科技大學營建工程研究所碩士論文。
8、 巫振春（2000），「單柱改良複合土體承受軸向力之力學性質與可靠度分析」，碩士論文，國立台灣科技大學營建工程研究所。
9、 杜明昇（2002），「攪拌樁應用於軟弱黏土深開挖之模型試驗」，國立台灣科技大學營建工程研究所碩士論文。
10、 黃啟瑞 （2005），「攪拌樁配置對軟弱黏土層島區開挖之影響」，國立台灣科技大學營建工程研究所碩士論文。
11、 陳煌銘（1987），「深開挖引致之地盤移動」，地工技術雜誌，第20期，第19-33頁。
12、 陳文洲（2004），「複合試體之異向性力學行為及強度評估」，碩士論文，國立台灣科技大學營建工程研究所。
13、 陳建和（2003），「複合土壤試體強度異向性之真三軸試驗研究」，碩士論文，國立台灣科技大學營建工程研究所。
14、 彭木田（1991），「深層攪拌工法強化深開挖安全性之探討」，碩士論文，國立台灣工業技術學院營建工程技術研究所。
15、 梁文耀 （2004），「壁外改良對黏土層深開挖行為影響之研究」，國立台灣科技大學營建工程研究所碩士論文。
16、 黃思銘 （2001），「軟弱黏土層深開挖之底部穩定模型試驗」，國立台灣科技大學營建工程研究所碩士論文。
17、 楊才賢（2004），「地盤改良對黏土層島區開挖行為之影響研究」，國立台灣科技大學營建工程研究所碩士論文。
18、 廖洪鈞 (1991)，「水泥攪拌樁強度和配置對軟弱土壤抗剪行為之影響」，中國土木水利工程學刊，第七卷，第一期，第23-33頁。
19、 廖洪鈞、林志誠、黃啟瑞（2005），「利用超軟黏土模型試驗探討地盤改良對黏土層島區式開挖之影響」，第十一屆大地工程學術研究討論會，台北縣萬里。
20、 廖洪鈞、林志誠、黃啟瑞 (2007)，「地盤改良對減低黏土層島區式開挖所引致土壤位移之效果」，2007海峽兩岸岩土工程/地工技術交流研討會，天津。
21、 廖洪鈞、許世宗（1990），「開挖擋土壁體之合理貫入深度探討」，地工技術雜誌，第32期，第78-89頁。
22、 廖瑞堂（1996），「逆打深開挖之行為研究」，國立台灣工業技術學院營建工程技術研究所博士論文。
23、 歐章煜（2002），「深開挖工程-分析設計理論與實務」，科技圖書出版。
24、 歐章煜、蕭文達 (1994)，「台北粉質粘土之不排水勁度特性」，中國土木水利工程學刊，第六卷，第二期，第233-237頁。
25、 歐章煜、謝百鈎（2000），「利用擬塑性模式於黏土不排水條件之深開挖分析」，中國土木水利工程學刊，第十二卷，第四期，第703-713頁。
26、 劉泉枝、謝旭昇、黃志祥（1997），「黏性土壤深開挖穩定性分析方法之探討」，第七屆大地工程學術研究討論會，台北金山，第629-638頁。
27、 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，國立臺灣工業技術學院工程技術研究所。
28、 盧紹均（2001），「單柱改良複合土體承受側向力之力學性質與可靠度分析」，碩士論文，國立台灣科技大學營建工程研究所。
29、 謝百鈎（1999），「黏土層開挖引致地盤移動之預測」，博士論文，國立台灣科技大學營建工程研究所。
30、 謝百鈎（2001），「黏土層深開挖引致地盤最大位移預測」，中國土木水利工程學刊，第十三卷，第三期，第489-498頁。
31、 謝百鉤（2002），「利用有限元素法分析土戧擋土開挖與問題探討」，地工技術雜誌，第93期，第43-52頁。
32、 蘇世豐 (2007)，「柱狀式改良地盤之異向性剪力強度」，2007海峽兩岸岩土工程/地工技術交流研討會，天津。
33、 American Society for Testing and Materials (ASTM) (2000), “Standard Test Method for Laboratory Miniature Vane Shear Test for Saturated Fine-Grained Clayey Soil,” D 4648-00, West Conshohocken, PA, USA.
34、 Bjerrum, L. and Eide, O. (1956), “Stability of Strutted Excavations in Clay,” Geotechnique, Vol. 6, No. 1, London, England, pp. 32-47.
35、 Bowles, J. E.（1986）, “Foundation Analysis and Design,” 4th Ed., McGraw-Hill Book Company, New York, USA.
36、 British Standard Institution (BSI), 1990, “Methods of Test for Soils for Civil Engineering Purposes,” BS 1377, London, UK.
37、 Burland, J. B., Simpson, B. and St John, H. D. (1979), “Movements around Excavations in London Clay,” Proceedings of 7th European Conference on Soil Mechanics and Foundation Engineering, Brighton 1, UK, pp. 13-29.
38、 Burland, J. B., Potts, D. M. and Walsh, N. M. (1981), “The Overall Stability of Free and Propped Embedded Cantilever Retaining Walls,” Ground Engineering, Vol. 14, No. 5, pp. 28-38.
39、 Clough, G. W. and Denby, G. M. (1977), “Stabilizing Berm Design for Temporary Walls in Clay,” Journal of the Geotechnical Engineering Division, ASCE, Vol. 103, No.GT2, pp. 75-90.
40、 Clough G. W. and O，Rourke, T. D. （1990）, “Construction-induced movement of insitu walls,” Design and Performance of Earth Retaining Structures, ASCE Special Publication, No.25, pp.439-470.
41、 Duncan, J. M. and C. Y. Chang (1970), “Nonlinear Analysis of Stress and Strain in Soils,” Journal of the Soil Mechanics and Foundations Division, ASCE, Vol. 96, No. 5, pp. 637-659.
42、 Feng, T. W. (2000), “Fall-cone penetration and water content relationship of clays,” Geotechnique, Vol. 50, No. 2, pp. 181-187.
43、 Georgiadis, M. and Anagnostopoulos, C. (1998), “Effect of Berms Sheet-Pile Wall Behaviour,” Geotechnique, Vol. 48, No.4, pp. 569-574.
44、 Hansbo, S. (1957), “A New Approach to the Determination of the Shear Strength of Clay by the Fall-Cone Test,” Proceedings of Royal Sweden Geotechnical Institution, Stockholm, No. 14, pp. 7-47.
45、 Head, K. H. (1982), “Manual of soil laboratory testing Volume2 Permeability shear strength and compressibility tests,” 中央圖書出版社。
46、 Hsieh, H. S., Lu, F. C., Wu, L.H. and Lin, Y. K. (1995), “Application of JG and DMP to Reduce Excavation Induced Diaphragm Wall Deflection,” Proceedings 10th Asia Regional Conference on Soil Mechanics and Foundations Engineering, International Academic Publisher, Beijing, China, pp. 403-406.
47、 Hsieh, H. S., Wang, C.C. and Ou, C. Y. (2003), “Use of Jet Grouting to Limit Diaphragm Wall Displacement of a Deep Excavation,” Journal of the Geotechnical and Geoenvironmental Engineering Division, ASCE, Vol. 129, No. 2, pp.146-157.
48、 Hsieh, P. G. and Ou, C. Y. (1997), “Use of the modified hyperbolic model in excavation analysis under undrained condition,” Geotechnical Engineering, SEAGS 28(2), pp.123-150.
49、 Houlsby, G. T. (1982), “Theoretical analysis of the fall-cone test,” Geotechnique, Vol. 32, No. 2, pp. 111-118.
50、 Iai, S. (1989), “Similitude for Shaking Table Tests on Soil-Structure-Fluid Model in 1g Gravitational Field,” Soils and Foundations, Vol. 29, No. 1, pp. 105-118.
51、 Itasca Consulting Group, Inc. (1997), FLAC3D Fast Lagrangian Analysis of Continua in 3 Dimensions, Version 2.0, Minnealopis, Minnesota, USA.
52、 Karlsson, R. (1961), “Suggested improvement in the liquid limit test, with reference to flow properties of remoulded clays,” Proceedings 5th Int. Conf. Soil Mech. Found. Eng, Paris, Vol. I, pp. 171~184.
53、 Kimura et al. (1993). “Stability of unsupported and supported vertical cut in soft clay,” Proceedings of 11th Southeast Asian Geotech. Conf., pp. 61-70, Singapore.
54、 Kusakabe, O. (1982). “Stability of excavation in soft clay” PhD. Thesis, Cambridge University.
55、 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, pp421-494.
56、 Liao, H. J., Lin, C.C. and Huang, C.J. (2005), “Case Studies on Grout Pile Improved Bermed Excavation in Taipei Silty Clay,” Proceedings of 6th International Conference on Ground Improvement Techniques, Coimbra, Portual, pp.393-400.
57、 Lin, H. D. and Chen, W. C. (2007), “Anisotropic Strength Characteristics of Composite Soil Specimen under Cubical Triaxial Conditions,” Journal of Mechanics, Vol. 23, No. 1, pp.41-50.
58、 Liu, C. J., Hsieh, H. S., and Wang, K. R. (1994), “Undrained Strength Parameters selection of Taipei City Soft Clay for Deep Excavation Design,” Proceedings of the Second Young Asian Geotechnical Engineers Conference, AIT, Bangkok, Thailand.
59、 Lyndon, A. and Schofield, A. N. (1970), “Centrifuge model test of short term failure in London clay,” Geotechnique, Vol. 20, No. 4, pp. 440-442.
60、 Madhav, M. R. and Krishna, K. S. R. (1977), “Undrained Modulus from Vane Shear Test,” Journal of the Geotechnical Engineering Division, ASCE, Vol. 103, No. 11, pp. 1337-1340.
61、 Mana, A. I., and Clough, G. W. (1981), “Prediction of Movements for Braced Cut in Clay,” Journal of the Geotechnical Engineering Division, ASCE, Vol. 107, No. 8, pp. 758-777.
62、 Naval Facilities Engineering Command (1982), Design Manual NAVFAC-7.2, Foundations and earth structures, Washington, DC: US Navy.
63、 O’Rourke, T. D. (1981), “Ground Movements Caused by Braced Excavations,” Journal of the Geotechnical Engineering Division, ASCE, Vol. 107, No. 6, pp.1159-1177.
64、 Ou, C. Y., Liao, J. T. and Lin, H. D. (1998), “Performance of Diaphragm Wall Constructed Using Top-Down Method,” Journal of Geotechnical and Geoenvironmental Engineering Division, ASCE, Vol. 124, No. 9, pp. 798-808.
65、 Ou, C. Y., Wu, T. S. and Hsieh, H. S. (1996), “Analysis of Deep Excavation with Column Type of Ground Improvement in Soft Clay,” Journal of Geotechnical Engineering Division, ASCE, Vol. 122, No. 9, pp. 709-716.
66、 Peck, R. B. (1969), “Deep Excavation and Tunneling in Soft Ground,” Proceedings of seventh International Conference on Soil Mechanics and Foundation Engineering,” State-of-the-Art Volume, Mexico City ,pp. 225-290.
67、 Seok, J. W., Kim, O. Y., Chung, C. K. and Kim, M. M. (2001), “Evaluation of Ground and Building Settlement near Braced Excavation Sites by Model Testing,” Canadian Geotechnical Journal, Vol. 4, No. 5990, pp. 70-87.
68、 Skempton, A. W. (1951), “The Bearing Capacity of Clays,” Proceedings of Building Research Congress Vol. 1, London, pp. 180-189.
69、 Skempton, A. W. and Northey, R. D. (1953), “The sensitivity of clays,” Geotechnique, Vol. 3, No. 1, pp. 30-53.
70、 Takada, N., Ohshima, A., Mikasa, M. and Kawamoto, K. (1988), “Centrifuge Model Tests on Anchored Sheet Pile Quay Wall on Clay Ground Improved by Sand Compaction Piles,” Proceedings of the International Conference on Geotechnical Centrifuge Modeling - Centrifuge 88, Paris, France, pp. 233-242.
71、 Takemura, J., Kondoh, M., Esaki, T., Kouda,M. and Kusakabe, O. (1999), “Centrifuge Model Tests on Double Propped Wall Excavation in Soft Clay,” Soils and Foundations, Vol. 39, No. 3, pp. 75-87.
72、 Terashi, M. (2003), “The State of Practice in Deep Mixing Methods,” Proceedings 3rd International Conference on Grouting and Ground Treatment, New Orleans, USA, ASCE Geotechnical Special Publication, No. 120, pp. 25-49.
73、 Terzaghi, K. (1943), “Theoretical Soil Mechanics,” John Wiley and sons, New York, N. Y.
74、 Terzaghi, K. and Peck, R. B. (1967), “Soil Mechanics in Engineering Practice,” 2nd Edition, John Wiley and sons, New York, N. Y.
75、 Wood, D. M. and Wroth, C. P. (1978). “The use of the cone penetrometer to determine the plastic limit of soil,” Ground Engng. Vol. 11, No. 3, pp. 37.
76、 Zreik, D. A., Ladd, C. C. and Germaine, T. T. (1995). “A new fall cone device for measuring the undrained strength of very weak cohesive soils,” Geotechnical Testing Journal, Vol. 18, No. 4, pp. 472-482.