During the construction of the zero cycle, some technological sequences were not followed. As a result, after the facility was put into operation, the base of the floor structures and foundations became wet, which led to soil washout and a significant change in the deformation modulus.

Task
Determine the degree of loosening of the foundation and ensure normal operating conditions for the facility (operation of the construction facility in accordance with the conditions provided for in building codes or the design brief, including appropriate maintenance, major repairs and reconstruction, GOST 27751‑2014, article 2.1.7).

First of all, URETEK specialists performed a visual inspection of the facility and determined a list of further actions. To determine the mechanical properties of the foundation soil, assess the uniformity of its structure, and identify and delineate loosened zones, dynamic probing of the foundation soil was carried out from the clean floor surface of the premises at 39 points in the suspected loosened zone. To determine the volume of voids that had formed under the floor slab structure, an inspection of the sub‑slab space was performed using a video scope. Data on slab irregularities were obtained by levelling surveys and recorded in a report on the work performed. After office processing of the results, a technical solution was developed that included:

• strengthening the foundation soils of 32 column foundations (columns) of the building frame using the Deep Injection method;
• deep strengthening of the foundation soils under 380 m² of the floor slab structure using the Deep Injection method;
• filling 14 m³ of voids in the foundation under the floor slab structure using the Slab Lifting method;
• lifting and levelling 430 m² of floor slab to ensure normal operating conditions using the Slab Lifting method. The maximum height difference was 15 cm.

All work was carried out inside an operating facility, with temporary restrictions on the use of certain zones. The URETEK injection method did not require complex equipment, improved the construction properties of the soils in their natural state, made it possible to work in the confined conditions of an operating facility, eliminated the filtration capacity of the soils, and also protected the foundations from possible aggressive environmental influences during operation.