Measured characteristics of a deep soft soil excavation in complex environment
YING Hong-wei1, 2, SUN Wei1, 2, LÜ Meng-jun3, CHEN Dong4
1. Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058,China; 2. MOE, Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education, Zhejiang University, Hangzhou 310058, China; 3. The Hangzhou canal group investment and Development Co., Ltd., Hangzhou 310014, China; 4. Zhejiang Province Institute of Architectural Design and Research, Hangzhou 310006, China
Abstract：The monitoring data of a 17.4 m~19.8 m-deep multi-strutted soft clay excavation built on hard shell layer soft soil foundation in Hangzhou is analyzed. The deep excavation is supported by a concrete diaphragm wall and multi-storey reinforced concrete brace. The monitoring includes soil and wall deflections, surface and subsurface ground settlements, axial forces of concrete struts. This study shows that the maximum horizontal displacements are 0.24%Hm~0.75%Hm, in which Hm is the total excavation depth. The maximum horizontal displacement is larger than 100 mm, in which the proportions of creep deformation reach up to 44%~56%. The horizontal creep rates are in 0.15~0.76 mm/d and closely related with the excavation depth and the properties of the soils near the base. The technology of T-diaphragm wall and partition wall can reduce the horizontal displacement of the excavation to some extent. The distribution of the lateral settlement is in a parabolic shape and the longitudinal settlement is in a saddle shape. The maximum settlements are 0.26%Hm ~0.7%Hm and the settlement rates are 0.1~0.6 mm/d. The relationship between the maximum settlements is between and 2.57, in which is the maximum horizontal displacement. The axial forces of the struts change dynamically during the excavation and construction or removal of the adjacent braces.
应宏伟, 孙威, 吕蒙军, 陈东. 复杂环境下某深厚软土基坑的实测性状研究[J]. 岩土工程学报, 2014, 36(zk2): 424-430.
YING Hong-wei, SUN Wei, LÜ Meng-jun, CHEN Dong. Measured characteristics of a deep soft soil excavation in complex environment. Chinese J. Geot. Eng., 2014, 36(zk2): 424-430.
 PECK R B. Deep excavation & tunneling in soft ground[C]// Proc 7th International Conference on Soil Mechanics and Foundation Engineering. Mexiocity, 1969: 225-281.  MANA A I, CLOUGH G W. Prediction of movements for braced cuts in clay[J]. Journal of Geotechnical Engineering Division, ASCE, 1981, 107(6): 759-777.  OU C Y, LIAO J T, LIN H D. Performance of diaphragm wall constructed using the top-down method[J]. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 1998, 124(9): 798-808.  LONG M. Database for retaining wall and ground movements due to deep excavations[J]. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2001, 127(3): 203-224.  LIU G B, NG C W W, WANG Z W. Observed performance of a deep multi-strutted excavation in Shanghai soft clays[J]. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2005, 131(8): 1004-1013.  WANG J H, XU Z H, WANG W D. Wall and ground movements due to deep excavations in Shanghai soft soils[J]. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2010, 136(7): 985-995.  应宏伟, 谢康和, 潘秋元, 等. 软黏土深基坑开挖时间效应的有限元分析[J].计算力学学报, 2000, 17(3): 349-354. (YING Hong-wei, XIE Kang-he, PAN Qiu-yuan, et al. FEM analysis on time-effects of deep excavations in soft clay[J]. Chinese Journal of Computational Mechanics, 2000, 17(3): 349-354. (in Chinese))  OU C Y, LAI C H. Finite-element analysis of deep excavation in layered sandy and clayey soil deposits[J]. Can. Geotech. J, 1994, 31(2): 204-214.  应宏伟, 杨永文, 胡安峰, 等. 软土某深基坑开挖的实测性状和环境效应分析[J]. 土木工程学报, 2011, 44(增刊): 90-93. (YING Hong-wei, YANG Yong-wen,HU An-feng,et al. Analysis on observed performance and environmental effect of a deep excavation in soft clay[J]. China Civil Engineering Journal, 2011, 44(增刊): 90-93. (in Chinese)).  MOORMAN C. Analysis of wall and ground movements due to deep excavations in soft soil based on a new worldwide database[J]. Soils and Foundation, 2004, 44(1): 87-98.  OU C Y, HSIEH P G, CHIOU D C. Characteristics of ground surface settlement during excavation[J]. Canadian Geotechnical Journal, 1993, 30(5): 758-767.