To the question of concrete creep in the soil environment

• Main Authors: Zaven G. Ter-Martirosyan, Viktor V. Bakhmisov
• Format: Article
• Language: English
• Published: Moscow State University of Civil Engineering (MGSU) 2020-09-01
• Series: Vestnik MGSU
• Subjects: concrete creep; reinforce concrete structure stiffness; pile stiffness; diaphragm wall stiffness; bentonite filter cake; relative humidity of the soil environment; water vapour in soil
• Online Access: https://doi.org/10.22227/1997-0935.2020.9.1285-1296

Introduction. Concrete creep coupled with specific soil properties represent a problem for the analysis of reinforced concrete structures in geotechnical engineering. The mission of this research is to make a problem statement and to outline its potential solutions. Materials and methods. In the course of the research, the finite element method was applied and the review of works, covering various problem aspects, was performed. Results. Concrete creep in respect of a diaphragm wall is most vividly manifested in deflections and stresses in struts; as for piles, concrete creep is manifested by the longitudinal axial force distribution along the length. The co-authors have demonstrated that is necessary to single out the excavations device under bentonite slurry protection from the viewpoint of the construction technology. In this case, a 5–10 mm thick water-saturated filter cake is formed at the contact between soil and concrete. The filter cake retains its permanent water penetrability at some level that depends on pressure and injection time; therefore, concrete in trench cannot be considered isolated from filtration water flows. Following the concrete mix casting into the trench, water saturated filter cake is consolidated, and this enables the authors to make a conclusion about its resistance to vapour penetration. Conclusions. If water saturation is equal to Sr > 0.5–0.6 and if excavation works are performed under the protection of the bentonite slurry, relative air humidity of soil RH can be considered to be equal to 100 %, and if water saturation Sr < 0.5–0.6, RH needs to be analysed. Identification of concrete moisture content depending on relative air humidity, the groundwater filtration flow and influence of the filter cake at the contact between ground and concrete make it possible to take account of the effect of soil conditions on concrete creep.