College of Mining, NUST MISIS, Moscow, Russia:

I. I. Shornikov, Associate Professor, Candidate of Engineering Sciences, shornicovivan@gmail.com

In tunneling projects for water-bearing ground using the microtunneling technology with jacking of casings, it is necessary to predict the jacking forces. The regulatory documents in tunneling miss the widely known fact of increase in the jacking forces at restarting after stoppage. It is of the current concern to study the physical processes which initiate the increase in the take-off resistance in the shield–casing system, in particular, in the contact zones of the shield shell–soil and the tunneling machine rotor–bottomhole. The model of end forces in the take-off resistance of a rammed system in straight-line portions during the shield shift is constructed. Both characteristics of the material in the shield clearance, representing a water and support medium mix (a slurry or a muck), and characteristics of counteractions of the support pressure as well as reaction of the tunnel heading in soil are taken into account. These forces are governed by own weight portion of the tunneling machine transferred to the soil skeleton, by the ground pressure, tunnel heading zone stiffness and also friction characteristics at the shifted object–shield clearance material contact. The results both of exact and of numerical solutions of the model problem on quasistatic deformation of the shifted object at the contact with the shield clearance material are presented as the jacking force–displacement dependences. The dependences of the take-off forces and maximal jacking forces on a set of parameters governed by the shear stiffness of the shifted object, bottomhole stiffness in soil and by the support pressure are derived. The obtained results make it possible to analyze more accurately the values of the bottomhole component of the jacking forces and its sensitivity to the change in the ramming parameters.

1. Microtunneling and Horizontal Drilling: French National Project “Microtunnels”. Recomendations. London : ISTE Ltd, 2006. 342 p.
2. Orlov V. A. Trenchless technologies of pipeline laying and maintenance. Moscow : MISI–MGSU, 2012. 210 p.
3. Maidl B., Thewes M., Maidl U. Handbook of Tunnel Engineering. Vol. 1: Structures and Methods. Berlin : Ernst & Sohn, 2013. 455 p.
4. STO NOSTROY 2.27.124-2013. Underground space development. Microtunneling. Regulations and control, performance requirements. Moscow : BST, 2015. 93 p.
5. Babendererde L. Problems of TBMs in Water Bearing Ground. Rational Tunnelling : Summerschool. Innsbruck, 2003.
6. Shornikov I. I. Driving force prediction in microtunneling technology with slurry shields: Estimation of end forces at tunneling shutdowns – II. GIAB. 2019. No. 7. pp. 42–52.
7. Uesugi M., Kishida H. Frictional resistance at yield between dry sand and mild steel. Soils & Foundations. 1986. Vol. 26, No. 4. pp. 139–149.
8. Naoui Tallah, Khemissa M. Modelling of the Soil-Structure Interface Behavior by Direct Shear Tests under Monotonous Loading. Proceedings of the 12^th International Congress on Advances in Civil Engineering. Istanbul, Turkey, 2016.
9. Mohamed Khemissa, Naoui Tallah, Boubakeur Bencheikh. Experimental and numerical modeling of the sand–steel interface behavior under monotonic loading. Innovative Infrastructure Solutions. 2018. Vol. 3. 25. DOI: 10.1007/s41062-018-0130-y
10. Nakayama H., Dietz M., Lings M., Muir Wood D. Modeling the Behavior of Sand-Steel Interfaces. Characterization and Behavior of Interfaces : Proceedings of Research Symposium on Characterization and Behavior of Interfaces. Amsterdam : IOS Press, 2010. pp. 78–84.
11. Liu S., Wang J. Exploring the influence of normal boundary conditions on interface shear test. Geomechanics from Micro to Macro : Proceedings of the TC105 ISSMGE International Symposium on Geomechanics from Micro to Macro. London : Taylor & Francis Group, 2015. Vol. 1. pp. 455–458.
12. Shornikov I. I. Jacking forces prediction for tunnel lining in microtunnelling technology: factor method. GIAB. 2016. No. 12. pp. 333–341.
13. Koronatov V. A. Introduction to rigorous theory of drilling. Sistemy. Metody. Tekhnologii. 2016. No. 4(32). pp. 83–94.
14. Apenkin N. A. Prediction of ground surface deformation induced by tunnelling in soft water bearing soils: a state-of-the-art review. Metro i tonneli. 2015. No. 5. pp. 8–12.
15. Protosenya A. G., Belyakov N. A., Do Ngoc Thai. The development of prediction method of earthpressure balance and earth surface settlement during tunneling with mechanized tunnel boring machines. Zapiski Gornogo instituta. 2015. Vol. 211. pp. 53–63.
16. Wong K. S., Ng C. W. W., Chen Y. M., Bian X. C. Centrifuge modelling of passive failure of tunnel face in saturated sand. Physical Modelling in Geotechnics : Proceedings of the 7th International Conference on Physical Modelling in Geotechnics. Leiden : CRC Press/Balkema, 2010. Vol. 1. pp. 599–604.
17. Xilin Lü, Zheng Su, Maosong Huang, Yuncai Zhou. Strength reduction finite element analysis of a stability of large cross-river shield tunnel face with seepage. European Journal of Environmental and Civil Engineering. 2017. DOI: 10.1080/19648189.2017.1383942
18. Di Prisco C., Flessati L., Frigerio G., Lunardi P. A numerical exercise for the definition under undrained conditions of the deep tunnel front characteristic curve. Acta Geotechnica. 2018. Vol. 13, Iss. 3. pp. 635–649.
19. Bulychev N. S. Mechanics of underground structures. Moscow : Nedra, 1982. 270 p.
20. Borodavkin P. P. Underground main pipelines. Moscow : Nedra, 1982. 384 p.
21. Kamke E. Differentialgleichungen: Lösungsmethoden und Lösungen. Band. I. Gewöhnliche Differentialgleichungen. 10 Aufl. Wiesbaden : Springer Fachmedien Wiesbaden GmbH, 1977. 670 s.