Dynamics of tidal parameters depending on the landslide hazard condition of the salt mine roof

The dynamics of tidal parameters were studied based on the results of tilt observations in 4 points of the landslide hazard zone, which was formed over the exhausted field of a salt mine in the city of Soledar, Donetsk region. The reduction in the thickness of the supporting walls of the salt mine led to the loss of their supporting stability, which led to the lowering of the ground, the destruction of the foundations and walls of residential and administrative buildings in a plot 1.3 km long and 0.5 km wide. To eliminate the risk of collapse, the used underground galleries were filled with salt in order to strengthen their retaining walls.Thus, the landslide hazard zone has become a unique training ground for studying the change in tidal parameters γ and Δϕ depending on the state of the mine roof. In total, 256 continuous hourly monthly series were processed using modern methods of excluding their linear drift and anomalous meteorological disturbances from the initial data at short observation intervals, which made it possible to significantly increase the accuracy of determining tidal parameters based on the results of harmonic analysis. For the first time in the global earth tide practice, the normalization of the tilt parameters during and after strengthening the collapsing roof of the mine was revealed. If before the strengthening of the supporting walls of the underground galleries, the tidal parameters assumed abnormal values (the amplitude factor γ by 30 %, and the phase factor Δϕ by 10—15 degrees differed from the regional analogues), then in the process of backfilling they began to approach their regional values, which they reached a year after the backfilling. The real possibility of using the earth tide method for monitoring and forecasting the landslide hazard and related phenomena of the ground has been proven.