In order to study the deformation law of the underground continuous wall + multi-layer support system of deep foundation pit in Fuzhou soft soil area, the deep foundation pit of the Pan Dun station of Metro Line 6# in Fuzhou soft soil area is used as the engineering research background. The body deformation and the internal force and deformation of the supporting structure and the surrounding surface settlement are dynamically measured and the measuring results are analyzed. The research results show that the horizontal displacement of soil and wall gradually increases with the increase of excavation depth. The maximum displacement occurs about 6m away from the basement, then gradually decreases, and the final deformation curve is “bulging type”. The measured subsurface settlement is a parabolic type of lateral surface settlement. The maximum settlement occurs at 7m away from the foundation pit wall. The maximum settlement is about 0.29Hm, which is 0.3%Hm. The longitudinal surface settlement is roughly linear; the multi-layer support is supported. The supporting axial force in the structural system changes dynamically with the earthwork excavation of each layer, the pouring, installation and removal of adjacent supports. The axial force of the upper and lower layers is obviously smaller than that of the intermediate support. The research results verify the reliability and rationality of the design of the deep foundation pit supporting structure-underground continuous wall + multi-layer support system, and have certain reference for the design and construction of other subway line sites and similar foundation pit projects in Fuzhou area.
deep foundation pit, deep silt layer, monitoring, deformation analysis
Hu H. Y., Zhang Y. C., Liu H. K., Luo Y. D., Rao C. Q. (2014). Case study of super-deep foundation pit of Pingan IFC. Chinese Journal of Geotechnical Engineering, Vol. 36, No. 1, pp. 31-38. http://dx.doi.org/10.11779/CJGE2014S1005
Li L., Yang M., Xiong J. H. (2007). Analysis of the deformation characteristics of deep excavations in soft clay. Chinese Journal of Geotechnical Engineering, Vol. 40, No. 4, pp. 66-72. http://dx.doi.org/10.3321/j.issn:1000-131X.2007.04.012
Liao S. M., Wei S. F., Tan Y. (2015). Field performance of large-scale deep excavations in Suzhou. Chinese Journal of Geotechnical Engineering, Vol. 37, No. 3, pp. 458-469. http://dx.doi.org/10.11779/CJGE201503009
Liu C., Zhang Y. L., Zheng G., Zheng J. C., Sun Y. N. (2016). Effects of seasonal temperature change on a large excavation project. Chinese Journal of Geotechnical Engineering, Vol. 38, No. 4, pp. 627-635. http://dx.doi.org/10.11779/CJGE201604006
Liu H. T., Wu X. G., Wang Z. (2014). The construction safety control analysis of super-deep and super-large foundation excavation for Wuhan greenland center project. Construction Technology, Vol. 43, No. 17, pp. 21-25.
Mana A. I., Clough G. W. (1981). Prediction of movements for braced cuts in clay. Geotechnical Special Publication, Vol. 107, No. 118, pp. 1840-1858. http://dx.doi.org/10.2514/3.56113
Moorman C. (2004). Analysis of wall and ground movementsdue to deep excavations in soft soil based on a newworldwide database. Soils and Foundation, Vol. 44, No. 1, pp. 87–98. http://dx.doi.org/10.3208/sandf.44.87
Wang J. H., Xu Z. H., Wang W. D. (2010). Wall and ground movements due to deep excavations in Shanghai soft soils. Journal of Geotechnical & Geoenvironmental Engineering, Vol. 136, No. 7, pp. 985-994. http://dx.doi.org/10.1061/(ASCE)GT.1943-5606.0000299
Xiong Z. B., Wang Q. Y. (2009). Monitoring horizontal displacements of support structure for a complicated planar foundation pit and its reinforcement. Rock and Soil Mechanics, Vol. 30, No. 2, pp. 572-576. http://dx.doi.org/10.1016/S1874-8651(10)60073-7
Ying H. W., Yang Y. W., Hu A. F., Xie K. H. (2011). Analysis on observed performance and environmental effect of a deep excavation in soft clay. China Civil Engineering Journal, Vol. 44, pp. 90–93.