Author 1:
Name & Surname: Fedorova L. L.
Company: Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences (Yakutsk, Russia)
Work Position: Head of Georadar Laboratory
Scientific Degree: Candidate of Engineering Sciences
Contacts: Lar-fed-90@rambler.ru

Author 2:
Name & Surname: Sokolov K. O.
Company: Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences (Yakutsk, Russia)
Work Position: Researcher
Scientific Degree: Candidate of Engineering Sciences

Author 3:
Name & Surname: Kulyandin G. A.
Company: Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences (Yakutsk, Russia)
Work Position: Junior Researcher

In order to enhance extraction of gold from placers at the reduced loss of commercial value minerals and increased overall efficiency of mining, it is required to have the live and reliable information on ground conditions of a deposit. The article illustrates application of georadar survey to studying geological conditions at placers developed by dredging in Yakutia. Thanks to low water salinity level at dredge sites (30–500 mg/l), georadar survey is efficient down to a depth of 8–10 m, with georadars with the center frequency of 100 MHz and below. For higher efficient georadar survey, the measurement procedure has been modified and now accounts for features of survey on water surface. When OKO-2 georadar moves over water surface at nonuniform velocity, the georadar and GPS data binding is incorrect, and georadar traces and geographical coordinates mismatch in number. Aimed at synchronization of georadar and GPS data (geographical coordinates), a software and hardware support has been developed that allows acquiring information on spatial coordinates of every georadar signal (trace). The algorithm of automated differentiation of damaged and undamaged rocks based on cluster estimate of georadar traces using the method of statistical analysis of an empirical correlation ratio is proposed. The article describes trial of the offered procedure at dredge sites of placers in the Allakh-Yun and Bolshoi Kuranakh river basins. Based on the data of georadar mapping of a site under mining by a bucket wheel suction dredge, 3D image of geological structure of the placer has been created, showing exposures of bed rocks in the excavation at depths of 4.5–7.5 m. The trial has proved the efficiency of georadar survey in delineation and mapping of hard rock areas, boulder inclusions, hypometria and damage of bedrock.

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