xpeditions-2009.

Georadiolocation in mines of the Republic of Belarus. Georadiolocation data in mines were kindly given by specialists of the laboratory of physico-mathematical methods in mining production investigations; research geologic-ecological department of OAO Belhimprom. They are working with our georadar GROT-12. The work objective was the more accurate definition of control-trunk mine location on Starodubninsk deposit of potash fertilizer in the Republic of Belarus to provide safe mining and exploitation of tail farm. The kernel of the problem is the following. In the case when control-trunk mines overstep the limits of exhausted mines in watered soils, they represent a danger in waterproof factor. To estimate the danger degree it is necessary to define the location of overstepping of control-trunk mines outside of mine holes contours. Also definition of areas with possible holes locations on the level of mine workings is required. It must be taken into account the presence of small watered soils in the bottom part of clay-marly stratum. It does not represent a danger in the threat of mine flood. But it can cause the difficulties in mine holes exploitation in the case of their immediate undermining of holes of control-trunk mines which cross clay-marly stratum outside mine holes contours. After finishing of mine boring and doing of hydrogeological and geophysical investigations the mine hole was cemented. During solving of location definition problem for bore 1K the selection of set of geophysical methods has been done. Methods included georadiolocation researches, high frequency seismic methods, ultrasonic researches. The diameter of borehole and surrounding broken soils reaches 20-25 cm. To view image in full scale double click on it by mouse. Survey georadiolocation work. To define location of borehole 2K georadiolocation researches by the profiling method were conducted. On the stage of experimental-methodical works for salted soils included the third potassium level, the value of permittivity has been defined (e ~8). Working zone (pillar adjoining to transport breakoff (east)). 12 January 2009. Development work allows to define the maximal depth for GROT-12. For example, with 2 meter antennas the possible depth for investigation of stratification is more 40 meters. For investigations transversely to stratification the depth is 30 meters with same antennas.   During experimental-methodical works the optimal schema of georadar investigations by profiling method has been formed. Due to size of excavations the antenna length should be 2 meter The transmitting and receiving antennas with combined design (1m rigid + 1m semi-flexible) were used. Such combined design made it possible to exclude noise from profile roughness in the maximal degree. In face of excavation beginning from the time 220 ns you can explicitly see reflections connected with concrete armor of borehole N1. Examples of radarogram and reflected signal (PK77.5m) with 2 meter antennas along transport breakoff between boreholes N2 and N1 (17 January 2009, breakoff face on PK78.7m).     Radarogram with parallel excavation at the distance 26 meters.   Georadar data processing allowed to define location of borehole relatively to the face existing on 17 January 2009.   Plan of georadar sounding.           Geradiolocation researches (face of transport breakoff between boreholes N2 and N1 on 12 January 2009).