Reliability is essential

Construction in St. Petersburg is far from easy. This is so due to engineering and geological conditions and the presence of historical buildings, which must be preserved. Senior Lecturer at the SPbGASU Department of Geotechnics, Ivan Dyakonov, Candidate of Engineering, is sure that the ill-considered application of foreign technologies is unacceptable here. Those should not be applied without a carefully developed theoretical and legal approach. All technologies must be verified and justified with the account of regional soil conditions.

– For the past five to six years, the SPbGASU Department of Geotechnics has conducted research on one of the most popular pile-supported technologies in our city: manufacturing piles in the ground. It has been in use for about 20 years, since it has a number of advantages. However, over time, defects began to be observed at construction sites. How can they be explained? How to eliminate them? We started looking for answers,” says Ivan Dyakonov.

– What are these defects about?

– Piles are made by the classical method: a cavity made in the ground is filled with concrete and reinforced. However, St. Petersburg is known for its complex geological and hydrogeological conditions: under high pressure, water penetrates the well, and there is a risk that the concrete of the pile shaft might be eroded. The second risk is related to how the piles are concreted. For a number of piles, concreting is carried out from the bottom up, to avoid stratification of the concrete mixture, but the method we are studying has certain technological limitations that have led to the fact that piles must be concreted from top to bottom. Just you imagine a mixture being thrown from a height of thirty meters down. Of course, it is quite likely that the mixture would delaminate during the hardening process.

– How did they take your research in the construction community?

– We worked in an atmosphere of absolute publicity. We conducted research at various sites, published articles on the results without delay, and received feedback, both positive and negative. It can be that our proposals will cause a rise in the price of technology. However, developers understand that reliability is the main thing. Professionals should know what to expect from each pile. The technologies that are used in our market must undergo quality control.

– What does the SPbGASU Department of Geotechnics do to achieve this goal?

– We train undergraduate and graduate students taking into account the latest developments of our Department. We are working on the creation of a separate standard for the piles we have studied. Teachers of the SPbGASU Department of Geotechnics under direction of the head of the department, Rashid Mangushev, regularly act as reviewers of regulatory documents; this allows them to come up with suggestions and recommendations. Being introduced into production, useful inventions of the authors of the SPbGASU Department of Geotechnics will help to avoid risk factors: the pile will be protected from groundwater, while the concrete technology will change.

✔ A technology for manufacturing piles, and in particular concretes, is the subject of a special chapter in my dissertation. Rashid Mangushev and I initially tried to limit ourselves to the scope of geotechnics, but it didn’t work out this way. The dissertations turned out to be quite comprehensive; it takes into account the technological aspects and defects of concrete. After all, the finished structure embraces technology, and structural elements, and building materials.

At SPbGASU, we managed to solve this complex problem thanks to the excellent equipment of the laboratories of the Department of Geotechnics, Department of Technology of Construction Production, Department of Technology of Construction Materials and Metrology, and the top qualification of the heads of these departments.

The results of the work and cooperation of the scientific teams of various departments of the Faculty of Civil Engineering, in my opinion, made it possible to develop a methodology for the implementation of complex field experiments of high practical value, scientific novelty and definite results.

– Could you please share your future plans?

– We are now working on two practical inventions aimed at eliminating identified defects. I would like to expand our study in terms of the operation of large pile fields, find out the magnitude of the effect of a particular pile defect on its life, develop a methodology for examining existing buildings on rammed piles.

Text: Tatyana Petrova

✔ Learn more about the Department of Geotechnics, Department of Construction Technology, and the Department of Technology of Construction Materials and Metrology