Excavation activities in undrained clays commonly result in a large ground
movement, which may induce basal heave instability and cause damage to the
adjacent building. One of the popular solutions to reduce excessive ground
movement is to improve the soil inside the excavation by means of jet grouting or
deep mixing soil method to enhance the block soil mass and increase the excavation
stability. Another possible solution is to install the buttress walls and cross walls as structural support system. However, most previous studies only focused on the
implementation of full improvement type and did not consider the real allocation of
improvement piles, whereas no study has conducted the excavation stability with
buttress and cross wall. Hence, a series of three-dimensional finite element analyses
were employed to assess the performance of ground improvement, buttress wall,
and cross wall in controlling excessive ground movement induced by the basal
heave instability. The stability analysis with the strength reduction method was
employed at the final excavation stage to obtain the factor of safety against basal
heave. The results revealed that the frictional resistance that act on the contact
surface area between the wall (diaphragm, buttress, and cross wall) and surrounding
soil is a key factor in resisting basal heave failure. In such a case, enlarging the
dimension of the buttress and cross wall could increase the frictional resistance area,
resulting in a higher safety factor. Furthermore, when the gap existed between the
wall and ground improvement, the untreated soil initially failed, causing the soil
inside the excavation to move upward along with ground improvement. Thus,
ground improvement should be directly contacted with the wall to effectively
enhance the wall friction. Moreover, new schematics of strut-free excavation
system was introduced by combining the buttress wall and ground improvement,
which could significantly enhance the excavation stability. In addition, new
simplified methods were proposed to estimate the safety factor for the case with
ground improvement, buttress walls, cross walls, and a strut-free retaining system,
which was further validated by the finite element results through the comprehensive
comparison.

Abdi, A. S., and Ou, C.Y. (2022). “A Study of the Failure Mechanism of Braced Excavations Using 3D Finite-Element Analysis.” International Journal of Geomechanics, 22(7), 1–14.

Abdi, A. S., and Ou, C. (2023a). “Numerical Study of the Effect of Ground Improvement on Basal Heave Stability for Deep Excavations in Normally Consolidated Clays.” Journal of Geotechnical and Geoenvironmental Engineering 149(7), 1–11.

Abdi A.S., and Ou, C.Y. (2023b). “Failure investigation of braced excavation in soft clays: case study on the collapse of Nicoll Highway.” IOP Conf. Series: Earth and Environmental Science. 1184:012010.

Abdi A.S., and Ou, C.Y. (2023c). “Numerical evaluation on the performance of deep excavation with the strut-free retaining system in clays.” 10th European Conference on Numerical Methods in Geotechnical Engineering. https://doi.org/10.53243/NUMGE2023-24.

ACI Committee 318 (1995) Building code requirements for structural concrete (ACI 318-95) and commentary (ACI 318R- 95). American Concrete Institute (ACI), Farmington Hills

Bayesteh, H., and Sabermahani, M. (2020). “Field study on performance of jet grouting in low water content clay.” Engineering Geology, Elsevier, 264(August 2019), 105314.

Bjerrum L, Eide O (1956) Stability of strutted excavation in clay. Geotechnique 1:32–47.

Blackburn, J. T., and Finno, R. J. (2007). “Three-Dimensional Responses Observed in an Internally Braced Excavation in Soft Clay.” Journal of Geotechnical and Geoenvironmental Engineering, 133(11), 1364–1373.

Brinkgreve, R., and Bakker, H. (1991). “Non-Linear Finite Element Analysis of Safety Factors.” Computer Method and Advances in Geomechanics.

Brinkgreve, R., Engin, E., and Swolfs, W. (2013). “PLAXIS 3D 2019 reference manual.” Delft, Netherlands.

Bryson, L. S., and Zapata-Medina, D. G. (2012). “Method for Estimating System Stiffness for Excavation Support Walls.” Journal of Geotechnical and Geoenvironmental Engineering, 138(9), 1104–1115.

Burland, J.B., Hancock, R.J.R., (1977) “Underground Car Park at the House of Commons, London: Geotechnical Aspects.” Structural Engineering 55:81–100.

Chang, M. F. (2000). “Basal stability analysis of braced cuts in clay.” Journal of Geotechnical and Geoenvironmental Engineering, 126(3), 273–275.

Chen, C.H. (2003). “A study on the anisotropic strength of composite soil specimen using true triaxial testing.” M.Sc. thesis, National Taiwan Univ. of Science and Technology, Taipei, Taiwan.

Chen, R. P., Li, Z. C., Chen, Y. M., Ou, C. Y., Hu, Q., and Rao, M. (2015). “Failure Investigation at a Collapsed Deep Excavation in Very Sensitive Organic Soft Clay.” Journal of Performance of Constructed Facilities, 29(3), 04014078.

Clough, G. W., and Hansen, L. A. (1981). ‘‘Clay anisotropy and braced wall behavior.’’ J. Geotech. Eng. Div., Am. Soc. Civ. Eng., 107(7), 893–913.

Clough, G. W. and O'Rourke, T. D. (1990), “Construction-induced movements of in situ walls.”, Design and Performance of Earth Retaining Structures, ASCE Special Publication, No. 25, pp. 439-470.

Clough, B. G. W., and Reed, M. W. (1984). “Measured behavior of braced wall in very soft clay.” Journal of Geotechnical Enginering, 110(1), 1–19.

Choosrithong, K., and Schweiger, H. F. (2020). “Numerical Investigation of Sequential Strut Failure on Performance of Deep Excavations in Soft Soil.” International Journal of Geomechanics, 20(6), 04020063.

Chowdhury, S. S., Deb, K., and Sengupta, A. (2013). “Estimation of Design Parameters for Braced Excavation: Numerical Study.” International Journal of Geomechanics, 13(3), 234–247.

Committee of Inquiry, COI. (2004). “Report of the Committee of Inquiry into the incident at the MRT circle line worksite that led to the collapse of Nicoll Highway.” (Singapore).

Corral, G., and Whittle, A. J. (2010). “Re-Analysis of Deep Excavation Collapse Using a Generalized Effective Stress Soil Model.” In Proc., Earth Retention Conf. 3, 720–731. Reston, VA: ASCE.

Do, T. N., Ou, C.-Y., and Lim, A. (2013). “Evaluation of Factors of Safety against Basal Heave for Deep Excavations in Soft Clay Using the Finite-Element Method.” Journal of Geotechnical and Geoenvironmental Engineering, 139(12), 2125–2135.

Do, T. N., and Ou, C. Y. (2020). “Factors affecting the stability of deep excavations in clay with consideration of a full elastoplastic support system.” Acta Geotechnica, Springer Berlin Heidelberg, 15(7), 1707–1722.

Do, T. N., Ou, C. Y., and Chen, R. P. (2016). “A study of failure mechanisms of deep excavations in soft clay using the finite element method.” Computers and Geotechnics, Elsevier Ltd, 73, 153–163.

Eide, O., Aas, G., and Josang, T. (1972). “Special applications of cast-in- place walls for tunnels in soft clay in Oslo.” Pub. 91, Norwegian Geotechnical Institute, Oslo, 63–72.

Endicott, J. (2013). “Case Histories of Failure of Deep Excavation Examination of Where Things Went Wrong: Nicoll Highway Collapse, Singapore.” 7th International Conference on Case Histories in Geotechnical Engineering, (3), 1–7.

Fang, Y. S., Liao, J.J., Lin, T. K. (1994). “Mechanical properties of jet grouted soilcrete”, Quarterly Journal of Engineering. Geology, 27(3):257-265.

Faheem H, Cai F, Ugai K. (2003). “Two-dimensional base stability of excavations in soft soils using FEM.”, Computers and Geotechnics; 30(2):141–63.

Faheem, H., Cai, F., and Ugai, K. (2004). “Three-dimensional base stability of rectangular excavations in soft soils using FEM.” Computers and Geotechnics, 31(2), 67–74.

Finno, R. J., and Roboski, J. F. (2005). “Three-dimensional responses of a tied-back excavation through clay.” Journal of Geotechnical and Geoenvironmental Engineering., 10 .1061/(ASCE)1090-0241(2005)131:3(273), 273–282

Finno, R. J., Blackburn, J. T., and Roboski, J. F. (2007). “Three-Dimensional Effects for Supported Excavations in Clay.” Journal of Geotechnical and Geoenvironmental Engineering, 133(1), 30–36.

Goh, A. T. C. (1990). “Assessment of Basal Stability for Braced Excavation Systems Using the Finite Element Method.” Computers and Geotechnics, 10, 325–338.

Goh, A. T. C. (1995). “Estimating basal heave stability for braced excavation in soft clay.” Journal of Geotechnical Engineering, 120(8), 1430-1436.

Goh, A. T. C., Kulhawy, F. H., and Wong, K. S. (2008). “Reliability Assessment of Basal-Heave Stability for Braced Excavations in Clay.” Journal of Geotechnical and Geoenvironmental Engineering, 134(2), 145–153.

Goh, A. T. C. (2017). “Deterministic and reliability assessment of basal heave stability for braced excavations with jet grout base slab.” Engineering Geology, Elsevier B.V., 218, 63–69.

Goh, A. T. C., Zhang, W. G., and Wong, K. S. (2019). “Deterministic and reliability analysis of basal heave stability for excavation in spatial variable soils.” Computers and Geotechnics, Elsevier, 108(July 2018), 152–160.

Gopal Madabhushi, S. P., and Chandrasekaran, V. S. (2005). “Rotation of Cantilever Sheet Pile Walls.” Journal of Geotechnical and Geoenvironmental Engineering, 131(2), 202–212.

Hartono, E., Wardani, S. P. R., and Muntohar, A. S. (2021). “The behavior of the clay shale stabilized by dry and wet cement mixing method.” Journal of GeoEngineering, 16(3), 81–90.

Hasofer, A. M., and Lind, N. C. (1974). “Exact and invariant second- moment code format.” J. Engrg. Mech. Div., 100(1), 111–121.

Ho, C. E., and Hu, S. (2006). “Numerical analysis of jet grout elements for braced excavation in soft clay.” GeoCongress 2006: Geotechnical Engineering in the Information Technology Age, 2006, 260.

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 Geotechnical and Geoenvironmental Engineering, 129(2), 146–157.

Hsieh, H. S., Wu, L. H., Lin, T. M., Cherng, J. C., and Hsu, W. T. (2011). “Performance of T-shaped diaphragm wall in a large scale excavation.” Journal of GeoEngineering, 6(3), 135–144.

Hsieh, P. G., Ou, C. Y., Lin, Y. K., and Lu, F. C. (2015). “Lessons learned in design of an excavation with the installation of buttress walls.” Journal of GeoEngineering, 10(2), 63–73.

Hsieh, P. G., and Ou, C. Y. (2018). “Mechanism of buttress walls in restraining the wall deflection caused by deep excavation.” Tunnelling and Underground Space Technology, Elsevier, 82(October 2017), 542–553.

Hsieh, P. G., Ou, C. Y., and Hsieh, W. H. (2016). “Efficiency of excavations with buttress walls in reducing the deflection of the diaphragm wall.” Acta Geotechnica, Springer Berlin Heidelberg, 11(5), 1087–1102.

Hsieh, H. S., Huang, Y. H., Hsu, W. T., and Ge, L. (2017). “On the system stiffness of deep excavation in soft clay.” Journal of GeoEngineering, 12(1), 21–34.

Hsieh, H. S., Cherng, J. C., Kuo, Y. T., Kuo, P. C., and Shen KC (2010) “Design of temporary support for a large scale top-down deep excavation project.” Sino-Geotechnics 124:73–82

Hsiung, B. C. B., Yang, K. H., Aila, W., and Hung, C. (2016). “Three-dimensional effects of a deep excavation on wall deflections in loose to medium dense sands.” Computers and Geotechnics, 80, 138–151.

Huang, M., Tang, Z., and Yuan, J. (2018). “Basal stability analysis of braced excavations with embedded walls in undrained clay using the upper bound theorem.” Tunnelling and Underground Space Technology, Elsevier, 79(May), 231–241.

Huang, J. X., Wang, Y. H., Nguyen, T. A., Hsu, C. S., and Hung, W. Y. (2021). “Soil Improvement By Microbial Induced Calcite Precipitation and a Chemical Method for Liquefaction Mitigation.” Journal of GeoEngineering, 16(1), 35–46.

Hung, T. N. H., Thanh, L. T., and Thang, L. H. (2013). “Soilcrete Characteristics Created by a Single Jet Grouting System in Ho Chi Minh City.” Geotechnics for Sustainable Development.

JSA (1988). “Guidelines of design andconstruction of deep excavaions.”, Japanese Society of Architecture.

Karlsrud, K., and Andresen, L. (2005). “Loads on Braced Excavations in Soft Clay.” International Journal of Geomechanics, 5(2), 107–113.

Keawsawasvong, S., and Ukritchon, B. (2019). “Undrained basal stability of braced circular excavations in non-homogeneous clays with linear increase of strength with depth.” Computers and Geotechnics, Elsevier, 115(July), 103180.

Khoiri, M., and Ou, C. Y. (2013). “Evaluation of deformation parameter for deep excavation in sand through case histories.” Computers and Geotechnics, Elsevier Ltd, 47, 57–67.

Kulhawy, F. H., and Jackson, C. S. (1989). “Some observations on undrained side resistance of drilled shafts.” In Foundation engineering: Current principles and practices (GSP 22). Edited by F. H. Kulhawy. ASCE, New York. Pp. 1011-1025

Kung, G. T., Juang, C. H., Hsiao, E. C., and Hashash, Y. M. (2007). “Simplified Model for Wall Deflection and Ground-Surface Settlement Caused by Braced Excavation in Clays.” Journal of Geotechnical and Geoenvironmental Engineering, 133(6), 731–747.

Lacasse, S. (1999). “The importance of dealing with uncertainties in foundation analysis.” Proc., 12th European Conf. Soil Mech. & Geo- tech. Eng., Balkema, Rotterdam, The Netherlands, 1, 385–392.

Ladd, C. C. and Foote, R. (1974), New design procedure for stability of soft clay, Journal of Geotechnical Engineering Division, ASCE, Vol. 100, GT7, pp. 763 - 786.

Lee, F. H., Yong, K. Y., Quan, K. C. N., and Chee, K. T. (1998). “Effect of Corners in Strutted Excavations: Field Monitoring and Case Histories.” Journal of Geotechnical and Geoenvironmental Engineering, 124(4), 339–349.

Lee, F. H., Hong, S. ., Gu, Q., and Zhao, P. (2008). “Application of large three-dimensional finite element analyses to practical problems.” 12th International Conference on Computer Methods and Advances in Geomechanics 2008, 1(December), 125–132.

Li, K. S., Lee, I. K., and Lo, S. C. R. (1993). “Limit state design in geotechnics.” Proc., Probabilistic Methods in Geotech. Eng., Balkema, Rotterdam, The Netherlands, 29–44.

Liao, H. J., Lin, C. C., and Huang, C. J. (2008). “Modeling the effect of ground improvement on reducing movement during bermed excavation in clay.” Journal of the Chinese Institute of Engineers, Transactions of the Chinese Institute of Engineers,Series A/Chung-kuo Kung Ch’eng Hsuch K’an, 31(1), 81–93.

Liao, H. J., and Su, S. F. (2012). “Base Stability of Grout Pile–Reinforced Excavations in Soft Clay.” Journal of Geotechnical and Geoenvironmental Engineering, 138(2), 184–192.

Liao, J. W. (2002). “Laboratory shear strength testing of composite soil specimen and its anisotropic characteristic.” M.Sc. thesis, National Taiwan Univ. of Science and Technology, Taipei, Taiwan.

Lim, A., Ou, C. Y., and Hsieh, P. G. (2010). “Evaluation of clay constitutive models for analysis of deep excavation under undrained conditions.” Journal of GeoEngineering, 5(1), 9–20.

Lim, A., and Ou, C.-Y. (2017). “Stress paths in deep excavations under undrained conditions and its influence on deformation analysis.” Journal of Tunnelling and Underground Space Technology; 63:118–32.

Lim, A., and Ou, C.-Y. (2018). “Performance and Three-Dimensional Analyses of a Wide Excavation in Soft Soil with Strut-Free Retaining System.” International Journal of Geomechanics, 18(9), 05018007.

Lim, A., Hsieh, P. G., and Ou, C. Y. (2016). “Evaluation of buttress wall shapes to limit movements induced by deep excavation.” Computers and Geotechnics, Elsevier Ltd, 78, 155–170.

Lim, A., Ou, C. Y., and Hsieh, P. G. (2019). “An innovative earth retaining supported system for deep excavation.” Computers and Geotechnics, Elsevier, 114(February), 103135.

Lim, A., Ou, C. Y., and Hsieh, P. G. (2020). “A novel strut-free retaining wall system for deep excavation in soft clay: numerical study.” Acta Geotechnica, Springer Berlin Heidelberg, 15(6), 1557–1576.

Lin, Y. L., (2010). “The effect of cross walls on the movements of excavations in clay.” M.Sc. thesis. National Taiwan University of Science and Technology, Taipei, Taiwan

Lin. Y. W., (1999) “Application of cross wall to the analysis of deep excavation.” M.Sc. thesis, National Taiwan Univ. of Science and Technology, Taipei, Taiwan.

Low, B. K. (2005). “Reliability-based design applied to retaining walls.” Geotechnique,55(1), 63–75.

Luo, Z., Atamturktur, S., Cai, Y., Juang, C.H., (2012). “Reliability analysis of basal-heave in a braced excavation in a 2-D random field. ” Computers and Geotechnics. 39, 27–37.

Mesri, G., and Huvaj, N. (2007). “Shear Strength Mobilized in Undrained Failure of Soft Clay and Silt Deposits.” (217), In Vol. 217 of Advances in measurement and modeling ofsoil behavior, Geotechnical Special Publication 173, edited by D. J. DeGroot, C.

Vipulanandan, J. A. Yamamuro, V. N. Kaliakin, P. V. Lade, M. Zeghal, U. El Shamy, N. Lu, and C. R. Song, 1–22. Reston, VA: ASCE.

Nowak, A. S. (2000). “Reliability of structures,” McGraw-Hill, New York.

Ohnisi, K., Katagiri, M., Saitoh, K. and Azuma, K. (2000). “Deformation behaviour and heaving analysis of deep excavation.” In: Kusakabe, Fujita and Miyazaki (eds). Geotechnical aspects of underground construction in soft ground. Rotterdam: Balkema, pp. 693-8.

Ou, C. Y. (2006). “Deep Excavation Theory and Practice.” London: Taylor & Francis.

Ou, C. Y., Chiou, D.-C., and Wu, T.-S. (1996a). “Three-dimensional finite element analysis of deep excavations.” Journal of Geotechnical Engineering, 122, 337–345.

Ou, C. Y., Wu, T. S., and Hsieh, H. S. (1996b). “Analysis of Deep Excavation with Column Type of Ground Improvement in Soft Clay.” Journal of Geotechnical Engineering, 122(9), 709–716.

Ou, C.Y., Shiau, B.Y., (1998) “Analysis of the corner effect on excavation behaviors.” Canadian Geotechnical Journal. 35: 532– 540.

Ou, C. Y., Lin, Y. L., and Hsieh, P. G. (2006). “Case record of an excavation with cross walls and buttress walls.” Journal of GeoEngineering, 1(2), 79–87.

Ou, C. Y., Teng, F. C., and Wang, I. W. (2008). “Analysis and design of partial ground improvement in deep excavations.” Computers and Geotechnics, 35(4), 576–584.

Ou, C. Y., Hsieh, P. G., and Lin, Y. L. (2013). “A parametric study of wall deflections in deep excavations with the installation of cross walls.” Computers and Geotechnics, Elsevier Ltd, 50, 55–65.

Ou, C. Y., Lin, C. Y., and Chien, S. C. (2020). “On the behavior of the cured electroosmotic chemical treated clay.” Acta Geotechnica, Springer Berlin Heidelberg, 15(8), 2341–2354.

O’Rourke, T. D. (1993). ‘‘Base stability and ground movement prediction for excavations in soft clay.’’ Retaining structures, Thomas Telford, London, 131–139.

Padfield, C. J., and Mair, R. J. (1984). Design of retaining walls embedded in stiff clays. CIRIA Report No. 104, England.

Panchal, J. P., McNamara, A. M., and Stallebrass, S. E. (2018). “Physical modelling of lime stabilisation in soft soils around deep excavations.” DFI Journal, Taylor & Francis, 11(2–3), 137–147.

Phan, H. K., Hsiung, B. C., and Huang, J. (2020). “Behaviours and mechanism analysis of deep excavation in sand caused by one-strut failure.” 16th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2019, (2012), 1–5.

Phoon, K. K., Kulhawy, F. H., (1999). “Characterization of geotechnical variability.” Canadian Geotechnical Journal. 36 (4), 612–624.

Pong, K. F., Foo, S. L., Chinnaswamy, C. G., Ng, C. C. D., and Chow, W. L. (2012). “Design considerations for one-strut failure according to TR26 - a practical approach for practising engineers.” IES Journal Part A: Civil and Structural Engineering, 5(3), 166–180.

Schäfer, R., and Triantafyllidis, T. (2006). “The influence of the construction process on the deformation behaviour of diaphragm walls in soft clayey ground.” International Journal for Numerical and Analytical Methods in Geomechanics, 30(7), 563–576.

Shen, S. L., Wang, Z. F., Horpibulsuk, S., and Kim, Y. H. (2013). “Jet grouting with a newly developed technology: The Twin-Jet method.” Engineering Geology, Elsevier B.V., 152(1), 87–95.

Shibazaki, M. and Ohta, S. (1982). “A unique underpinning of soil solidfication utilizing super-high pressure liquid jet.” Proceedings, Conference on Grouting on Geotechnical Engineering, ASCE, New Orleans, 680-693.

Shirlaw, J. N. (2004). “Copyright ASCE 2004 Grouting and Ground Treatment Grouting 2003.” Grouting and Ground Treatment, American Society of Civil Engineering.

Tanaka, H. (1994). “Behavior of braced excavations stabilized.” Soils and Foundations, Elsevier Masson SAS, 33(2), 105–115.

Tang YG, Kung GTC (2007) “Wall deflection and surface settlement induced by deep excavation: case studies in the Zone K-1 of Taipei basin.” J Chinese Inst Civ Hydraul Eng 19(3):329–339.

Teng, F., Ouedraogo, C., and Sie, Y. C. (2020). “Strength improvement of a silty clay with microbiologically induced process and coir fiber.” Journal of GeoEngineering, 15(2), 79–88.

Teparaksa W (1993) “Behavior of deep excavations using sheet pile bracing system in soft Bangkok clay.” Proc, 3rd Int Conf Case Hist Geotech Eng 745–750.

Terzaghi, K. (1943). “Theoretical soil mechanics”. New York : John Wiley & Sons.

TGS (2001). “Design specifications for the foundation of the building.”, Taiwanese Geotechnical Society.

Uchiyama, N., and Katsura, Y. (1984). “Case studies of buttress-wall type ground improvement in strutted excavations.” Geotechnical Aspects of Underground Construction in Soft Ground, Kusakabe, Fujita & Miyazaki (eds), 1(2), 161–162.

Ukritchon, B., Whittle, A. J., and Sloan, S. W. (2003). “Undrained Stability of Braced Excavations in Clay.” Journal of Geotechnical and Geoenvironmental Engineering, 129(8), 738–755.

Whittle, A. J., Corral, G., Jen, L. C., and Rawnsley, R. P. (2015). “Prediction and Performance of Deep Excavations for Courthouse Station, Boston.” Journal of Geotechnical and Geoenvironmental Engineering, 141(4), 04014123.

Whittle, A. J., and Davies, R. V. (2006). “Nicoll Highway collapse: evaluation of geotechnical factors affecting design of excavation support system.” International Conference on Deep Excavations, 28(June), 30.

Wen, D. (2015). “Use of Jet Grouting in Deep Excavations.” Ground Improvement Case Histories: Chemical, Electrokinetic, Thermal and Bioengineering Methods, 109–122.

Wong, I.H., Poh, T.Y., (2000). “Effects of jet grouting on adjacent ground and structures. ” Journal of Geotechnical and Geoenvironmental Engineering. ASCE 126 (3), 247–256.

Wu, S. H., Ching, J., and Ou, C. Y. (2013). “Predicting Wall Displacements for Excavations with Cross Walls in Soft Clay.” Journal of Geotechnical and Geoenvironmental Engineering, 139(6), 914–927.

Wu, S. H., Ou, C. Y., and Ching, J. (2014). “Calibration of model uncertainties in base heave stability for wide excavations in clay.” Soils and Foundations, Elsevier, 54(6), 1159–1174.

Yeh, T., Ou, C.-Y., and Lim, A. (2022). “A case study of strut-free excavation retaining system.” Acta Geotechnica, 17(12), 5557-5571.

Yu, C.H., Chang, T.K., Yang, H.W., (2010) “Design and construction management of deep excavation for site adjacent to High Speed Rail.” Sino-geotech 124:33–44

Zdravkovic, L., Potts, D. M., and St. John, H. D. (2005). “Modelling of a 3D excavation in finite element analysis.” Geotechnique, 55(7), 497–513.

Zhang, S. D. and Zhang, H. D. (1994). “Stability of deep excavation in soft clay.” Centrifuge 94, Singapore, pp. 643-647.

Zhang, W., Hong, L., Li, Y., Zhang, R., Goh, A. T. C., and Liu, H. (2021). “Effects of jet grouting slabs on responses for deep braced excavations.” Underground Space (China), Tongji University, 6(2), 185–194.

Zhang, W., Li, Y., Goh, A. T. C., and Zhang, R. (2020). “Numerical study of the performance of jet grout piles for braced excavations in soft clay.” Computers and Geotechnics, Elsevier, 124(May), 103631.