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Will St. Petersburg have its own leaning tower of Pisa?

пизанская башня
© pixabay.com

A second skyscraper may appear opposite Moscow Victory Park, just 2 meters lower than Lakhta Center. The proposal has provoked heated discussions among experts on the safety of the construction for the surrounding area.

The investors of the project are business structures that own shares in the hotels Russia, Vyborzhets, and the Baltiets resort. They ask KGA to issue permission for changing construction limits on Chernyshevsky Square.

The initiative has caused serious resistance. Thus, the head of the regional branch of the “Fair Russia” Marina Shishkina noted that the foundation of the skyscraper would require a very deep foundation pit. This would violate the geodesic integrity of a large built-up area, endangering the foundations of nearby homes and the “blue” subway line.

гостиница Россия
© Dezidor, Википедия

Public hearings to discuss the construction of a 460-meter building on the site of the Soviet-time hotel are scheduled for December 31. Of course the opinion of citizens must be taken into consideration, but it is up to specialists to decide if the project can be realized.

Today, about 300 companies work on the St. Petersburg market of engineering surveys. The desire to expand the portfolio of orders pushes many of them to dumping prices when taking part in tenders, which then leads to savings on the process of research. Forpost addressed one of the most reputable companies in the city in the field of surveying ZAO LenTISIZ for comments.

“In St. Petersburg and its immediate surroundings there is a variety of soils, from weak clay to rock, construction on them requires the most careful study of their physical and mechanical properties. The thickness of weak clay soils of fluid and flowable plastic consistence occupies up to 70% of the area of the city, which leads to the widespread use of pile foundations. All old buildings rest on the top layers, which are usually lake-marine sands. Everywhere occur situations where modern construction has led to above-normal deformations and damage to neighboring buildings. Therefore, the situation requires strict control. In this context the issue of training well-qualified specialists in engineering surveys becomes acute once again," says Nikolay Oleynik, Director General of the company, which has been operating since 1962.

лентисиз
© Из личного архива

Any construction process starts with – be that residential and industrial buildings, structures and linear objects. No matter what tasks are set by the customer, no building or structure can be erected without surveys. The Town Planning Code and common sense obligate this.

Surveying implies a comprehensive study of the site for future construction: information on underground utilities, topography, and neighboring buildings. The data obtained are used to develop technically and economically sound solutions in the design and construction of the facility.

Of course, in world practice, there are enough examples when the builders ignored this part of the preparatory work, did it poorly or in insufficient quantity. The scale of the consequences was directly proportional to the degree of neglect - from deformations and settlements of buildings and structures to their complete destruction. At best, this leads to a several-fold increase in the cost of zero-cycle work.

обрушение
© Википедия

In California, for example, the dam collapsed just two years after construction was completed. The capacity of the reservoir was 46 million cubic meters. When the accident occurred, the water gushed from 30-meter height down the valley and swept away everything in its path. The damage was vast, not to mention the many victims. According to many commissions, the catastrophe was caused by a change in the physical and mechanical properties of the soil induced by the water. They had not been studied before the construction. The base of the dam was made of shale, gypsum, and clay. The gypsum dissolved and the clay softened, and the strength of the soil dropped by 2-3 times. This led to the formation of a large scour and, subsequently, to the collapse of the entire structure.

In terms of housing construction, the collapse of a five-story building with 100 apartments in Tula could be a good example. The cause of its deformations was also the surveyors' incorrect assessment of the properties of the foundation soils. Using the values listed in the SNiP, the surveyors did not take into account that these tables apply only to the Quaternary deposits. The house was built on clay soils of the Lower Carboniferous deposits. When exposed and moistened, their strength properties tend to decrease dramatically.

But the most beloved example of all engineering surveyors is the Tower of Pisa. Now a cultural treasure, it is, in fact, a mistake of engineers who did not take into account the heterogeneity of local soils during construction. Work to reinforce its position is carried out regularly.

“There is no need to cite examples from global and all-Russian experience - there are plenty of them in St. Petersburg. They take place even at very large facilities. Naturally, such information is not disclosed if possible: it is fraught with scandals. Usually, the accidents are caused by two reasons: the desire of the developer to save money and incompetence of specialists. For example, the survey should be conducted for a specific project. If its parameters change during the process, a new survey must be ordered. For example, during the construction of the new Arbitration Court of St. Petersburg and the Leningrad region on Smolnaya embankment, in the final design stage the depth of the projected underground parking lot was increased from 6 to 12 meters. Additional engineering surveys (hydrogeological studies) were skipped, which resulted in an emergency situation with a groundwater breakthrough in the pit during the construction of the underground part of the building.”

арбитражный суд
© spb.arbitr.ru

"In the current circumstances we prefer to work with development companies that are willing to carry out the necessary range of work, and form our own team of only well-qualified professionals. Engineering surveys include geological, geodesic, ecological and hydrometeorological works. Among the field- specific universities training staff in these areas of activity, Mining University is one of the leaders. Its graduates work for us: geodesists from the Faculty of Civil Engineering, hydrogeologists and geotechnical engineers from the Faculty of Geological Surveying, and ecologists from the Mining Faculty," says Nikolay Oleinik, a graduate of the university.

After graduation, he joined Lentisiz as an engineer. While working, he completed his Bachelor's and Master's degrees at SPbGASU. He studied at the evening department and attended classes every day after work. According to him, this was done to improve his skills, expand his competence, and to communicate with construction clients in the same professional language. At the same time, he feels himself a mining engineer.

Over the 12 years of his career, Nikolay Oleinik has held the positions of head of the field team, deputy head of the engineering geology department, and deputy chief engineer. In 2015, he became Director General of the company and currently manages a team of 140 employees. The portfolio of the organization he heads includes such landmark for the city projects as the Pulkovo Airport, the Ring Road, the reconstruction of the Hermitage, the Embankment of Europe, and many others.

лентисиз
© Пресс-служба "ЛенТИСИЗ"

Geodetic surveying has undergone considerable modernization in recent years. Old theodolites and levels have been replaced by modern GNSS-receivers. Aerial photography of the survey area is performed with the help of drones, land laser scanning is used in the reconstruction of industrial objects, and three-dimensional digital models of objects are created based on the received data.

"Progress has also touched the laboratory equipment used in conducting engineering and geological surveys. Thanks to the automation of instruments, the human factor in soil testing is now reduced to a minimum. You load a sample into the device, and at the output you actually receive a formalized protocol of laboratory tests. Today the Russian level of testing is in no way inferior to the Western one, but it requires regular retraining of the employees. Young professionals get this knowledge at higher educational institutions. Graduates from my alma mater demonstrate a high level. Students scan facades during practical classes, then process the resulting point cloud and create 3D models of buildings and structures. Mining University supplies as many ready-made specialists as possible. That’s why they make up about 40% of our engineering staff,” says Nikolay Oleynik.

лентисиз
© Строительство Второй сцены Мариинского театра

"Projects can cost hundreds of millions, and surveys are only 5-10% of the total cost of the design and survey work. No the major development companies or industrial enterprises want to risk their reputation, so every year more and more attention is paid to the experience of the company, its staff, and its survey equipment when choosing a surveyor," says Nikolai Oleinik.

Whether the city on the Neva will have its own Leaning Tower of Pisa or a project we will be proud of depends on how professional the surveys that will form its basis will be.