Вестник МГТУ, 2021, Т. 24, № 2.

Шеков В. A. Природные риски и системы мониторинга. A feature of the proposed method is the patent formula, which allows using one rangefinder with a special mechanism for installing it on the special base to provide tens and even hundreds of observation points. The device is designed in such a way that when it sets on a base, it always indicates the point whose mobility is controlled. This significantly reduces the cost of conducting observations, which can be performed by one person, even not very highly qualified (including conducting visual examinations) during the work shift. The frequency of measurements is selected based on current conditions and is determined over a long period of time. For Ruskeala Mountain Park it has been recommended to carry out such measurements once every 3-4 weeks. In Fig. 14, a - the length of the laser beam is about 2 m, in Fig. 14, b - the laser beam length reaches 8 m. The distance to control is determined by the rangefinder range and the accuracy of the measurement. Modern laser rangefinders provide up to 1 mm accuracy in devices that cost less than $100 and applied for up to 100 meters. a b Fig. 14. Examples of measurements in various conditions in underground workings Рис. 14. Примеры измерений в различных условиях в подземных выработках For small distances in open areas, it is possible to use a modified measurement method, here it is uses two metal screws embedded in the rock, as shown in Fig. 15. Fig. 15. Scheme to install metal screws embedded in the rock for measurements with laser devices Рис. 15. Схема установки металлических саморезов (реперов) в скале для измерений лазерными устройствами 224