Conducting mine workings in weak unstable rocks is difficult and requires the use of special methods-freezing of rocks, injection of fixing substances, dewatering. The greatest difficulties for mining operations are clay water-saturated rocks with weak filtration capacity, which cannot be hardened by most of the widespread methods. At present, mining in such conditions is carried out mainly with the use of freezing of rocks.

In the Tikhvin mining district in the open-pit mining method in the sides of the quarries are exposed mainly sandy and clayey rocks of the Carboniferous and covering them Quaternary boulder loams. In a number of quarries of the region, landslides of the sides and rock ledges are observed, and less frequently their slides. During snowmelt or as a result of precipitation, the Quaternary rocks are overmoistened, and their bearing capacity is sharply reduced. Decrease in bearing capacity of boulder loams adversely affects the working conditions of walking excavators: their maneuverability decreases, the base of the excavator often sinks into the ground up to 0,4-0,5 m, sometimes the bearing capacity of the over-moistened over-wet soil is insufficient and excavators without additional measures (sand and gravel-pebble cushions, scaffolding under the pile, etc.) can not work at all ....