Rock and Soil Mechanics ›› 2023, Vol. 44 ›› Issue (8): 2389-2399.doi: 10.16285/j.rsm.2022.6114

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A calculation method for deformation of diaphragm wall of narrow deep foundation pit in soft soil considering spatio-temporal effect

ZHANG Kun-yong1, 2, ZHANG Meng2, SUN Bin3, LI Fu-dong4, JIAN Yong-zhou4   

  1. 1. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing, Jiangsu 210024, China 2. Geotechnical Research Institute, Hohai University, Nanjing, Jiangsu 210024, China; 3. Jiangsu Zhongshe Group Co. Ltd., Wuxi, Jiangsu 214072, China 4. China Communications Construction Co., Ltd-Second Highway Bureau Fourth Engineering Co., Ltd., Luoyang, Henan 471000, China
  • Online:2023-08-22 Published:2023-10-31
  • About author:ZHANG Kun-yong, male, born in 1975, PhD, Professor, mainly engaged in teaching and research on the basic soil properties, soil–structure interaction, and numerical analysis of geotechnical engineering.
  • Supported by:
     the National Natural Science Foundation of China (41530637).

Abstract: To accurately evaluate the safety of foundation pit construction in soft soil area and its impact on the surroundings, the time and space influencing factors during excavation cannot be ignored. In this paper, based on the excavation of a deep foundation pit in the soft soil area of the Yangtze River floodplain, a 3D finite element model was established considering the combination of bottom-up and top-down constructions, and the calculated values of horizontal displacement of the diaphragm wall were compared with the measured values to verify the reliability of the finite element calculation. Based on theoretical analysis, numerical calculation and measured data, the influence coefficient of corner effect and equivalent horizontal resistance coefficient were used to measure the influence of spatio-temporal effect on the deformation of supporting wall, and the calculation method of the diaphragm wall deformation considering spatio-temporal effect was proposed. The necessity of the spatio-temporal effect and the rationality of the proposed method in the design of foundation pit in soft soil area were verified by engineering examples. The results can provide beneficial reference for the calculation of deep foundation pit deformation in soft soil area. 

Key words: foundation pit excavation, numerical simulation; spatio-temporal effect, retaining structure deformation calculation