In April 1986, a survey of the brickwork of the remains of the Assumption Cathedral was conducted, during which samples of mortar, plinths and bricks were selected in order to identify the characteristics of their strength. Analysis of the results showed that the strength of plinfs and bricks is in the range of 5.7–20 MPa, and the strength of the masonry solution is 3.7–13 MPa. Cracking of the outer surface of the masonry under the influence of periodic locking and significant temperature fluctuations was recorded; in some of the investigated areas, the masonry solution disintegrated into separate pieces and crumbled, in some places the mortar was lost to a depth of 2-10 cm. The masonry wall was wetted , vidiiaruvannya tinkuvalnogo layer of masonry, and in places of loss of plaster on the surface of the masonry was observed the appearance of water-soluble salts. Plinfa and bricks in the places of fixation of the appearance of water-soluble salts disappeared, some plinfs were destroyed to a depth of 10 cm. At some sites there were deposits of masonry, especially in rubble stones. Both ancient and later masonry have a small significant number of cracks with a disclosure of 1-3 mm. Later cement laying of the masonry contributed to the accumulation of moisture in the masonry, which led to its destruction and the detachment of cement plaster together with the upper layer of bricks and plinfs.

Based on the results of the research, the following conclusions were formulated:

  1. The existing masonry of the Assumption Cathedral is significantly weakened as a result of the above destructive factors, emergency areas of the masonry were fixed;
  2. In order to protect the masonry from further destruction, it is necessary to perform work to strengthen the masonry (according to the recommendations of the specialists-restorers);
  3. The greatest strength is characterized by ancient plinf (130-170 kg / cm sq.), The smallest – brick (60 kg / cm sq.)

When conducting research in 1998, the results of studies from 1972 to 1986 were analyzed, systematized and supplemented. In particular, it was noted that the construction in 1986-1987 around the cathedral spot to the height of the decorative structure covered with sand and an asphalt podium for the basing of heavy machinery during the restoration of the cathedral led to a deterioration of living conditions and preservation of the remnants of the Assumption Cathedral because they turned out to be in a kind of pool, precipitation fell inside the debris and accumulated under layers of decorative masonry, asphalt and concrete floors, since there was no drainage system, soil moisture Under the surface coating, s and residues were 25%, that is, they were in a saturated state of moisture. The perennial defrost cycles have turned the surface layer of the ancient structure to a freezing conglomerate to the depth of frost penetration. The territory on which the Assumption Cathedral is located was conventionally divided into three zones: a zone of complete destruction within the epicenter of the explosion, a zone of significant destruction with remnants of ancient walls, and a zone of partial destruction with St. John theological chapel that survived the explosion. The complexity of the tasks was that a significant part of the ruins was split into separate elements and deformed, and according to the restoration requirements, all remnants of ancient structures needed to be preserved and given the possibility of their further study. In addition, John the Bogoslovsky Chapel was in acute emergency condition.

Previously conducted by the Research Institute of Building Structures of the study of the state of the foundations using the electroquilm method made it possible to identify defects in the body of some of the foundations. For example, the foundations under the northern wall of the XI century. had significant damage. In the tape foundations between the northern wall and the north-western subcapital column, cracks, displacements and hollows were recorded. Cracks and potholes of masonry were fixed in the foundations of the southern wall. The foundations in the northwestern corner of the sacristy were in relatively good condition.

The difficulty lay in the fact that the depth of the foundations in different parts of the cathedral was different. For example, the fifth foundations of the southern wall, which consisted of large blocks of sandstone on a pale-pink lime-cement mortar, were at a depth of 2.5 m. Five foundations of the north-western part of the cathedral, which consisted of horizontal rows of large stones of sandstone sandy solution with the inclusion of white brick, were at a depth of 2.75 m from the level of plates conservation floor. The fifth basement of the northern apse, which consisted of stone and plinfs on a white lime mortar with admixture of crushed ceramics, was located at a depth of 3.6 m from the level of asphalt. The foundation fifth buttress at the location of the southern apse to the central one was located at a depth of 3.30 m from the level of asphalt, and the foundation itself consisted of large boulders with the inclusion of plinths on a lime-sand gray solution.

It was noted that Plinf and solutions of the XI century. are among the strongest among the monuments of Kievan Rus of the pre-Mongol period, therefore the re-conservation of the remains of the masonry of the cathedral from the top layer should be done urgently in order to use the summer period to dry the entire spot of the cathedral. Block masonry pylon XI. it was proposed to move the cathedral beyond the spot, to preserve and preserve as a peculiar memory of the destroyed unique structure.