Backfilling; Grout hardening; Numerical simulation; Shielded mechanized tunneling; Two-component grout; Earth pressure balance; Finitedifference methods (FDM); Mechanical stiffness; Mechanized tunneling; Storage and transportations; Tunnel boring machine(TBM); Two-component; Civil and Structural Engineering; Building and Construction; Materials Science (all); Mechanics of Materials; General Materials Science
Abstract :
[en] In shielded mechanized tunneling, the annular gap caused by the tunnel boring machine (TBM) driving must be backfilled instantaneously using a suitable grout. A two-component grout composed of a chemically retarded cement slurry and an accelerator is pumped into the annular gap behind the TBM shield, where it gels and attains sufficient mechanical stiffness in a very short time. This property of the grout helps restrict immediate ground movements adjacent to the TBM tail shield and reduce volume loss. In this study, the hardened twocomponent mix is tested using a confined oedometric condition, and a complete time-dependent hardening stiffness evolution is developed. Moreover, the freshly prepared grout is tested in terms of its performance suitability (storage and transportation) and serviceability owing to permeability and dewatering. The obtained parameters from the oedometer tests are incorporated into a numerical simulation of an earth pressure balance (EPB) excavation focusing on modeling of the backfilling procedure using finite-difference method (FDM) software. The study also focuses on distinguishing between two commonly used backfilling techniques implemented in numerical analyses. The numerical model consists of testing a regular tunnel section using a newly introduced hardening soil (HS) constitutive model with the soil parameters obtained from the Torino, Italy, metro case. Another set of synthetic softer soil parameters are chosen to highlight the soil properties in the model response. The two-component grout satisfies all the prerequisites for a good backfilling material in its fresh and hardened state. The grout attains sufficient mechanical strength in a very short time, remains impermeable, and achieves a stiffness of 43 MPa in 28 days. The results obtained from the oedometer tests enable development of a complete time-dependent stiffness evolution of the grout. The implementation of hardening behavior of the two-component grout is evident in terms of ground settlements when compared with the conventional backfilling simulation technique.
Disciplines :
Civil engineering
Author, co-author :
Shah, Ravi; Dept. of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Torino, Italy
ALIMARDANI LAVASAN, Arash ; University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Engineering (DoE)
Peila, Daniele; Dept. of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Torino, Italy
Todaro, Carmine; Dept. of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Torino, Italy
Luciani, Andrea; Dept. of Environment, Land and Infrastructure Engineering, Politecnico di Torino, Torino, Italy
Schanz, Tom; Foundation Engineering, Soil and Rock Mechanics, Ruhr-Universität Bochum, Bochum, Germany
External co-authors :
yes
Language :
English
Title :
Numerical study on backfilling the tail void using a two-component grout
This research has been supported by the German Research Foundation (DFG) through the Collaborative Research Center (SFB 837). The authors would like to express utmost gratitude to the organization for constant support and funding during this research. They would also like to express sincere appreciation toward Itasca consulting group for providing the license to use FLAC3D under the Itasca education partnership and their constant mentorship during the period of this research. The authors would also like to thank Infra. To for providing valuable data from the Torino metro case.
Anagnoustou, G., and Kovari, K. (1996). "Face stability in slurry and EPB shield tunneling." Geotechnical aspects of underground construction in soft ground, R. J. Mair and R. N. Taylor, eds., A.A. Balkema, Rotterdam, Netherlands, 453-58
ASTM. (2003). "Standard test method for one-dimensional consolidation properties of soils." ASTM D2435-03, West Conshohocken, PA
ASTM. (2016). "Standard test method for expansion and bleeding of freshly mixed grouts for preplaced-aggregate concrete in the laboratory." ASTM C940-16, West Conshohocken, PA
Cheng, Z., and Dettournay, C. (2016). "Plastic hardening model. I: Implementation in Flac 3D." Proc., 4th Itasca Symp. on Applied Numerical Modelling, Itasca International Inc., Minneapolis, 267-77
Dai, Z., Bai, Y., Peng, F., and Liao, S. (2010). "Study on mechanism of simultaneous backfilling grouting for shield tunnelling in soft soils." GeoShanghai Int. Conf. on Deep and Underground Excavations, ASCE, Reston, VA, 182-190
Demagh, R., Emeriault, F., and Hamnoud, F. (2013). "3D modelling of tunnel excavation using pressurized tunnel boring machine in overconsolidated soils." Studia geotechnica et mechanica, 35(2), 3-17
FLAC3D version 5.0 [Computer software]. Itasca Consulting Group, Inc., Minneapolis
Gilbert, R. I., and Ranzi, G. (2011). Time-dependent behaviour of concrete structures, Taylor & Francis/CRC Press, Boca Raton, FL
Guglielmetti, V., Grasso, P., Mahtab, A., and Xu, S. (2008). Mechanized tunneling in urban areas: Design methodology and construction control, Taylor & Francis/A.A. Balkema, Leiden, Netherlands
Italian Standards. (2005). "Water suspensions of hydraulic binders for grouting-Characteristics and test methods." UNI 11152:2005-13, Milano, Italy
Kasper, T., and Meschke, G. (2006). "A numerical study of the effect of soil and grout material properties and cover depth in shield tunnelling." Comput. Geotech., 33(4-5), 234-247
Lambrughi, A., Medina Rodriguez, L., and Castellanza, R. (2012). "Development and validation of a 3D numerical model for TBM-EPB mechanized excavations." Comput. Geotech., 40, 97-113
Lavasan, A. A., and Schanz, T. (2017). "Numerical investigation of hydromechanical interactions at the tail void of bored tunnels due to grouting." Proc., 9th Int. Symp. on Geotechnical Aspects of Construction in Soft Ground, A.A. Balkema, Rotterdam, Netherlands
Oh, J. Y., and Ziegler, M. (2014). "Investigation on influence of tail void grouting on the surface settlements during shield tunnelling using a stress pore pressure coupled analysis." KSCE J. Civ. Eng., 18(3), 803-811
Peila, D., et al. (2015). "Long term behaviour of two component backfill grout mix used in full face mechanized tunneling." Geoingegneria ambientale e mineraria, 1, 57-63
Peila, D., Borio, L., and Pelizza, S. (2011). "The behaviour of a twocomponent back-filling grout used in a tunnel boring machine." ACTA geotechnica Slovenica, 1, 5-15
Pelizza, S., Peila, D., Borio, L., Dal Negro, E., Schulkins, R., and Boscaro, A. (2010). "Analysis of the performance of two-component back-filling grout in tunnel boring machines." ITA-AITES World Tunnel Congress 2010, Tunneling Association of Canada, Vancouver, Canada
Pelizza, S., Peila, D., Sorge, R., and Cigritti, F. (2012). "Backfill grout with two component mix in EPB tunneling to minimize settlements: Rome metro-line C case history." Geotechnical aspects of underground construction in soft ground, CRC Press, Boca Raton, FL, 291-99
Schanz, T., Vermeer, P., and Bonnier, P. (1999). "The hardening soil model: Formulation and verification." Proc., 1st Int. PLAXIS Symp. on Beyond 2000 in Computational Geotechnics, A.A. Balkema, Rotterdam, Netherlands, 281-96
Shah, R., Peila, D., and Lucarelli, A. (2016). "Tunneling with full face shielded machines: A study on the backfilling of the tail void." ITA-AITES World Tunnel Congress, San Francisco, 1505-1514
Shah, R., Zhao, C., Lavasan, A. A., Peila, D., Schanz, T., and Lucarelli, A. (2017). "Influencing factors affecting the numerical simulation of the mechanized tunnel excavation using FEM and FDM techniques." IV Int. Conf. on Computational Methods in Tunneling and Subsurface Engineering, Studia Universitätsverlag, Innsbruck, Austria, 483-490
Thewes, M., and Budach, C. (2009). "Grouting of the annular gap in shield tunneling-An important factor for minimisation of settlements and production performance." 35th ITA-AITES World Tunnel Congress, Hungarian Tunnelling Association, Budapest, Hungary
Vakili, K., Lavasan, A. A., Schanz, T., and Datcheva, M. (2014). "The influence of the soil constitutive model on the numerical assessment of mechanized tunneling." Proc., 8th European Conf. on Numerical Methods in Geotechnical Engineering, CRC Press/A.A. Balkema, London, 889-894
Zhao, C., Lavasan, A. A., Barciaga, T., Kämper, T., Christoph, M., and Schanz, T. (2017). "Prediction of tunnel lining forces and deformations using analytical and numerical solutions." Tunnelling Underground Space Technol., 64, 164-176
Zhao, C., Lavasan, A. A., Barciaga, T., Zarev, V., Datcheva, M., and Schanz, T. (2015). "Model validation and calibration via back analysis for mechanized tunnel simulations The Western Scheldt tunnel case." Comput. Geotech., 69, 601-614
