Deformation characteristics of ultra-deep circular shaft in soft soil: A case study

Abstract

A circular shaft is often used to access a working well for deep underground space utilization. As the depth of underground space increases, the excavation depth of the shaft increases. In this study, the deformation characteristics of a circular shaft with a depth of 56.3 m were presented and analysed. The main monitoring contents included: (1) wall deflection; (2) vertical wall movement; (3) horizontal soil movement; (4) vertical surface movement; and (5) basal heave. Horizontally, the maximum wall deflection was only 7.7 mm. Compared with the wall deflection data collected for another 29 circular excavations, the ratio of maximum wall deflection to excavation depth of this shaft was smaller due to a smaller ratio of diameter to excavation depth. The wall deflection underwent two stages of deformation: the first stage was mainly circumferential compression caused by the mutual extrusion of joints between walls, and the second stage was typical vertical deflection deformation. The horizontal soil movement outside the shaft was greater than the wall deflection and the deep soil caused great horizontal movement because of dewatering at confined water layers. Vertically, a basal heave of 203.8 mm occurred in the pit centre near the bottom. Meanwhile, the shaft was uplifted over time and showed 3 stages of vertical movement. The surface outside the shaft exhibited settlement and uplift deformation at different locations due to different effects. The basal heave caused by excavation was the dominant factor, driving the vertical movement of the shaft as well as the surrounding surface. The correlation between the wall deflection and the surface settlement outside the shaft was weak.

Keywords

Circular shaft / Site monitoring / Deflection / Vertical deformation / Soft soil

CRediT authorship contribution statement

Yafei Qiao: Conceptualization, Investigation, Methodology, Formal analysis, Writing - review & editing, Supervision, Funding acquisition. Feng Xie: Methodology, Formal analysis, Validation, Writing - original draft. Zhanwei Bai: Data curation, Investigation. Jiafeng Lu: Data curation, Investigation. Wenqi Ding: Conceptualization, Investigation, Supervision, Funding acquisition.

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This research was financed by the National Natural Science Foundation of China (Grant No. 52090083), Shanghai Chenguang Program (Grant No. 20CG26) and Consulting project on Shanghai deep tunnel project.

References

[1] Abbas, Q., Yoon, J., & Lee, J. (2023). Characterization of Wall Deflection and Ground Settlement for Irregular-Shaped Excavations with Changes in Corner Configuration. International Journal of Geomechanics, 23(1), 04022258.

[2] Bian, Y. H., Huang, H. M., & Zhang, D. M. (2004). Monitoring and analysis of deep excavation in whirlpool of Baogang rolling mill. Rock and Soil Mechanics, S2, 491-495 (in Chinese).

[3] Cabarkapa, Z., Milligan, G. W. E., Menkiti, C. O., Murphy, J., & Potts, D. M. (2003). Design and performance of a large diameter shaft in Dublin Boulder Clay. In Proceedings of the BGA International Conference on Foundations: Innovations, observations, design and practice. 2-5 September 2003, Dundee, Scotland. pp. 175-185.

[4] Chehadeh, A., Turan, A., Abed, F., & Yamin, M. (2017). Lateral earth pressures acting on circular shafts considering soil-structure interaction. International Journal of Geotechnical Engineering, 13(2), 139-151.

[5] Chen, W. X. (2021). Research on Mechanical Characteristics and Influencing Factors of Retaining Structure of Circular Ultra-deep Shaft. [Master’s thesis, South China University of Technology, China]. (in Chinese).

[6] Chen, X. Q., Ding, W. Q., Qu, H. B., Qiao, Y. F., Lu, X. B., & Lai, S. Y. (2020). Influence of insertion ratio of large-diameter piles in deep mud stratum of deofrmation characteristics of foundation pit in Zhuhai. Journal of Central South University (Science and Technology), 51(9), 2514-2524 (in Chinese).

[7] Chen, Y. F., Zhang, Q. H., Zhou, J., & Wang, Y. (2006). Half-inverted construction and supervision on circular special deep foundation excavation. Chinese. Journal of Geotechnical Engineering, s1, 1865-1869 (in Chinese).

[8] Dong, X. P., Guo, Q. H., & Zhou, S. H. (2005). Character and Factor Analysis of Deformation of Diaphragm Wall in the Cylindrical Foundation Pit. Chinese Journal of Underground Space and Engineering, 2, 196-199 (in Chinese).

[9] East China Architectural Design & Research Institute Co., Ltd, & Shanghai Construction Group Co., Ltd (2018). Technical code for excavation engineering (DG/TJ 08-61-2018). Shanghai: Tongji University Press (in Chinese).

[10] Hsieh, P. G., & Ou, C. Y. (1998). Shape of ground surface settlement profiles caused by excavation. Canadian Geotechnical Journal, 35(6), 1004-1017.

[11] Jia, J., Zhai, J. Q., Li, M. G., Zhang, L. L., & Xie, X. L. (2019). Performance of Large-Diameter Circular Diaphragm Walls in a Deep Excavation: Case Study of Shanghai Tower. Journal of Aerospace Engineering, 32(5), 04019078.

[12] Kim, D. S., & Lee, B. C. (2005). Instrumentation and numerical analysis of cylindrical diaphragm wall movement during deep excavation at coastal area. Marine Georesources & Geotechnology, 23(1-2), 117-136.

[13] Kim, K. Y., Lee, D. S., Cho, J., Jeong, S. S., & Lee, S. (2013). The effect of arching pressure on a vertical circular shaft. Tunnelling and Underground Space Technology, 37, 10-21.

[14] Kumagai, T., Ariizumi, K., & Kashiwagi, A. (1999). Behaviour and Analysis of A Large-Scale Cylindrical Earth Retaining Structure. Soils and Foundations, 39(3), 13-26.

[15] Kung, G. T. C. (2009). Comparison of excavation-induced wall deflection using top-down and bottom-up construction methods in Taipei silty clay. Computers and Geotechnics, 36(3), 373-385.

[16] Liu, R. Y., Hua, D. J., & Chen, K. J. (2021). Experimental study on interaction between rock granular flow and different structural forms of rigid retaining walls. Structures, 34, 3557-3566.

[17] Long, M. (2001). Database for retaining wall and ground movements due to deep excavations. Journal of Geotechnical and Geoenvironmental Engineering, 127(3), 203-224.

[18] Moormann, C. (2004). Analysis of wall and ground movements due to deep excavations in soft soil based on a new worldwide database. Soils and Foundations, 44(1), 87-98.

[19] Ng, C. W. W., Hong, Y., Liu, G. B., & Liu, T. (2012). Ground deformations and soil-structure interaction of a multi-propped excavation in Shanghai soft clays. Géotechnique, 62(10), 907-921.

[20] Ou, C. Y., Hsieh, P. G., & Chiou, D. C. (1993). Characteristics of ground surface settlement during excavaion. Canadian Geotechnical Journal, 30 (5), 758-767.

[21] Ou, C. Y., Liao, J. T., & Lin, H. D. (1998). Performance of Diaphragm Wall Constructed Using Top-Down Method. Journal of Geotechnical and Geoenvironmental Engineering, 124(9), 798-808.

[22] Peck, R. B. (1969). Deep Excavations and Tunneling in Soft Ground. In Proceedings of the 7th International Conference on Soil Mechanics and Foundation Engineering (pp.225-290).

[23] Placzek, D. (2005). Load bearing capacity of large-size, circular excavation walls without horizontal supporting systems. In Proceedings of the 16th International Conference on Soil Mechanics and Geotechnical Engineering (pp.1537-1541).

[24] Qiao, Y. F., Ding, W. Q., Wang, J., & Wang, C. B. (2012). Deformation characteristics of deep excavations for metro stations in Wuxi. Chinese Journal of Geotechnical Engineering, 34(s1), 761-766 (in Chinese).

[25] Ren, B. K., Shen, Y., Zhao, T. T., & Li, X. J. (2023). Deformation monitoring and remote analysis of ultra-deep underground space excavation. Underground Space, 8, 30-44.

[26] Schwamb, T., Elshafie, M. Z. E. B., Soga, K., & Mair, R. J. (2016). Considerations for monitoring of deep circular excavations. Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 169 (6), 477-493.

[27] Shi, J. W., Liu, G. B., Huang, P., & Ng, C. W. W. (2015). Interaction between a large-scale triangular excavation and adjacent structures in Shanghai soft clay. Tunnelling and Underground Space Technology, 50, 282-295.

[28] Song, Q. J., & Wang, W. D. (2010). Analysis of monitored displacement and stress of deep cylindrical structure for the 500 kV World Expo Underground Transmission and Substation project during excavation by top-down method. Journal of Building Structures, 31(5), 181-187 (in Chinese).

[29] Tan, Y., Lu, Y., Xu, C. J., & Wang, D. L. (2018). Investigation on performance of a large circular pit-in-pit excavation in clay-gravelcobble mixed strata. Tunnelling and Underground Space Technology, 79, 356-374.

[30] Tan, Y., & Wang, D. L. (2013). Characteristics of a Large-Scale Deep Foundation Pit Excavated by the Central-Island Technique in Shanghai Soft Clay. I: Bottom-Up Construction of the Central Cylindrical Shaft. Journal of Geotechnical and Geoenvironmental Engineering, 139 (11), 1875-1893.

[31] Tangjarusritaratorn, T., Miyazaki, Y., Sawamura, Y., Kishida, K., & Kimura, M. (2022). Numerical investigation on arching effect surrounding deep cylindrical shaft during excavation process. Underground Space, 7(5), 944-965.

[32] Watanabe, K., Munaf, Y., Koseki, J., Tateyama, M., & Kojima, K. (2003). Behaviors of several types of model retaining walls subjected to irregular excitation. Soils and Foundations, 43(5), 13-27.

[33] Xu, Q. W., Gong, Z. Y., Sun, Z. L., Hu, R. C., & Hu, K. F. (2022). Analysis on the monitoring results of construction deformation and internal force of ultra-deep circular foundation pit of Dianzhong Water Diversion Project. China Civil Engineering Journal, 55(6), 102-111 (in Chinese).

[34] Xu, Y. S., Shen, S. L., & Du, Y. J. (2009). Geological and hydrogeological environment in Shanghai with geohazards to construction and maintenance of infrastructures. Engineering Geology, 109(3-4), 241-254.

[35] Yang, G. H., Zhang, W. Y., Chen, F. Q., & Li, Z. L. (2022). Research on the Hoop Rigidity Non-Linear and Self-locking Effect of Circular Diaphragm Wall. Chinese Journal of Underground Space and Engineering, 18(5), 1639-1648 (in Chinese).

[36] Yang, Y. Q., Wu, H., & Liu, M. H. (2006). Monitoring Technology and Research of Wuhan Yangluo Yangtze Highway Bridge South Anchor Deep Foundation. In Proceedings of the the Second National Geotechnical and Engineering (pp.548-575) (in Chinese).

[37] Yuan, H., & Zhang, Q. (2010). Three Dimensional Performance Observed in an Irregular Deep Excavation in Shanghai Soft Clay. In Proceedings of the Geoshanghai International Conference (pp.107-113).

[38] Zhao, Y. X., Zhan, G. Y., Shi, Y. F., Liang, X. H., Jiang, Y. L., & Zhu, Y. D. (2021). Analysis of the Size Effect of a Ultra-Deep Circular Foundation Pit Under Stress and Deformation. Journal of East China Jiaotong University, 38(5), 23-29 (in Chinese).