Changes in stress-strained soil mass resulting from the installation of bored cast-in-situ piles and barrettes

Introduction. The paper considers the effect produced by the installation of bored cast-in-situ piles and barrettes on the stress-strain state of the surrounding soil mass for four different types of soil conditions.
Aim. To develop a procedure for determining concrete-induced stress acting on walls that enclose a borehole filled with concrete, as well as stress changes during relaxation.
Materials and methods. An analysis of experimental studies is performed, both those conducted by the present authors and those available in open sources. By means of back calculations relying on experimental data, the dependence is determined between the maximum concrete-induced stress and the rate of concr eting. The results of post-construction monitoring are used to derive a formula for describing stress relaxation following the completion of concreting works.
Results. In this study, the authors proposed a bilinear formula, developed a procedure, and calculated the concrete-induced stress acting on the walls that enclose a borehole filled with concrete, as well as stress changes in the process of relaxation. The effect of the adopted pile installation technique and soil conditions on changes in the stress-strain state of soil mass was studied. A formula was provided for determining the final values of horizontal stresses at the pile-soil interface at the full grade strength of concrete following stress relaxation in the soil, as well as recommendations for numerically calculating changes in the stressstrain state of soil mass during concreting and subsequent concrete hardening in piles and barrettes.
Conclusions. The conducted studies into the effect of bored cast in-situ pile installation on the stress-strain state of surrounding soil mass revealed that this stress-strain state depends on the soil conditions of the site, as well as the adopted pile installation technique. Due to the fact that soil is a plastic material, the final value of horizontal stresses is affected by the technique-dependent load dynamics and the soil conditions of the site, which should be taken into account by applying appropriate soil models.

1. Shulyatyev O.A. Foundations and foundations of high-rise buildings. Moscow: ASB Publ.; 2020 (in Russian).

2. Dzagov A.M., Sidorchuk V.F. On the stressed state of the foundation during the construction and loading of a bored pile in clay soils. Osnovaniya, fundamenty i mekhanika gruntov = Soil Mechanics and Foundation Engeneering. 2002;(3):10–15 (in Russian).

3. Mamonov V.M., Ermoshkin P.M. Investigation of the conditions for the formation of the bearing capacity and strength of the trunks of bored piles Osnovaniya, fundamenty i mekhanika gruntov = Soil Mechanics and Foundation Engeneering. 1982;(1):10–14 (in Russian).

4. Mamonov V.M., Dzagov A.M., Ermoshkin P.M. Bearing capacity of bored piles made of concrete of various composition. Osnovaniya, fundamenty i mekhanika gruntov = Soil Mechanics and Foundation Engeneering. 1989;(1):11–14 (in Russian).

5. Lings M.L., Ng C.W.W., Nash D.F.T. The Lateral Pressure of Wet Concrete in Diaphragm Wall Panels Cast under Bentonite. Proceedings of the Institution of Civil Engineers-Geotechnical Engineering. 1994;107(3):163–172. https://doi.org/10.1680/igeng.1994.26469

6. Lings M.L., Nash D.F., Ng C.W.W., Boyce M.D. Observed Behavior of a Deep Excavation in Gault Clay. In: Proceedings 10th European Conference on Soil Mechanics and Foundation Engineering. Vol. 2. Florence; 1991, p. 467–470.

7. Loreck C., Triantafyllidis T. Berücksichtigung des Frischbetondrucks bei der FE-Simulation der Schlitzandherstellung. Bautechnik. 2007;(9):646–655. https://doi.org/10.1002/bate.200710055

8. Ng C.W.W., Rigby D.B., Lei G.H., Ng S.W.L. Observed performance of a short diaphragm wall panel. Géotechnique. 1999;49(5):681–694. https://doi.org/10.1680/geot.1999.49.5.681

9. Delattre L., Duca V. Measured pressure exerted by a fine soil on a diaphragm wall under construction. In: Proceedings of the international symposium on geotechnical aspects of underground construction in soft ground. Lyon; 2002, p. 547–552.

10. Lächler A., Neher H.P., Gebeyhu G. A comparison between monitoring data and numerical calculation of a diaphragm wall construction in Rotterdam. In: Proceedings of thе international conference on numerical simulation of construction processes in geotechnical engineering for urban environment. Bochum, Germany; 2006, p. 83–96.

11. Lächler A., Vermeer P.A., Wehnert M. Assessment of diaphragm wall stability and deformation. In: XIV European conference on soil mechanics and geotechnical engineering. Madrid; 2007, p. 1055–1060.

12. Uriel S., Oteo C.S. Stress and strain besides a circular trench wall. In: Proceedings of the 9th conference on soil mechanics and foundation engineering. Tokyo; 1977, p. 781–788.

13. Gaba A., Hardy S., Doughty L., Powrie W., Selemetas D. Guidance on embedded retaining wall design. London: CIRIA; 2017.

14. Shulyatyev O.A., Minakov D.K. The pressure of fresh concrete on the walls of the trench when installing a wall in the ground. Geotekhnika = Geotechnics. 2017;(6):30–38 (in Russian).

15. Dzagov A.M. Development of a method for calculating the resistance of the foundations of bored piles taking into account the process of concrete hardening [Dissertation]. Leningrad; 1986 (in Russian).

16. Petrukhin V.P., Shulyatyev O.A., Mozgacheva O.A. New methods of geotechnical design and construction: Scientific publication. Moscow: ASB Publ.; 2015 (in Russian).