Ivan Strelbitskii was involved in the assessment, conservation and structural stabilisation of the historic underground monastic complex at Sarov. The work included the underground church, passages, ventilation system and areas affected by unstable dolomite ground, water infiltration and collapsed karst formations.

The historic monastery developed on a hill between the Sarovka and Satis rivers. Its underground structures were cut into dolomite rock at depths of up to approximately 14 metres. The underground system included passages, monastic cells, a church and ventilation shafts.

The geology of the site was highly variable. Stronger areas of dolomite alternated with weak vertical karst formations filled with dolomite flour and sand, referred to as ponors. These conditions strongly influenced both the original layout of the passages and the later structural problems encountered during conservation works

The underground complex had suffered from long-term water leakage, blocked ventilation and structural deterioration. Some areas of the church vault had collapsed, while weak geological zones created cavities and unstable ground above the historic passages.

The ventilation system had been blocked and relative humidity was close to 100%, with an approximately constant underground temperature of 8°C. Restoring ventilation became an important part of the conservation strategy.

Unstable Dolomite Ground
Weak karst formations and soft infill.

Water Infiltration
Long-term leakage from underground services.

High Humidity
Blocked ventilation and moisture accumulation.

Structural Collapse
Damaged vaults and unstable emergency passages.

Vault Stabilisation

Damaged sections of the underground church vaults were stabilised using steel anchors installed into drilled holes with expanding cement mix. Metal mesh was fixed to the anchors and cavities were filled with lightweight expanded-clay concrete.

Ventilation & Moisture Control

Blocked ventilation shafts were reopened and restored. Together with natural ventilation, additional heating was used to reduce excessive moisture within the underground church.

1. Initial Surface Stabilisation
The weak ground was treated repeatedly with liquid latex spray until preliminary excavation could begin safely.

2. Removal of Collapsed Material
Loose material was progressively removed from the blocked passage.

3. Temporary Support
Scaffolding was erected and also used to support the upper part of the unstable ground mass.

4. Permanent Structural Solution
A combined structure was adopted: reinforced concrete approximately 15 cm thick was constructed behind permanent 12 cm brickwork shuttering.

5. Layer-by-Layer Construction
The structure was built progressively, with reinforcement and concrete introduced behind the brickwork.

6. Final Grouting
After completion of the vault, the remaining upper void was filled by cement injection to reduce the risk of further void development.

An unexpected archaeological discovery

During the works, a feature resembling the entrance to another underground passage or monk’s cell was discovered. Because there was insufficient time and funding for full investigation, an arched portal was formed so that the area could be studied in the future. A nearby historic icon case was also preserved.

The works combined conservation of historic fabric with targeted structural intervention. The approach aimed to retain as much original material as possible while providing safe and durable reinforcement in areas affected by geological instability, moisture and previous collapse.