Investigation task:

• Delineation of zones of different strength within a block.
• Detection of coal horizon occurrence under overlapping deposits.
The investigation was carried out along parallel georadar profiles directed along the site edge at 10 m distance between them.
Profile №1 – closer to the edge.
Profile №5 – farther from the edge.
Scanning depth – 100 m
Site №1 is located on a hitch 60-65 m beneath ground surface (absolute marks 783-785 m above sea level).
Presumed (visible along the pit wall) depth of the coal horizon occurrence on Site №1 – from 10 to 30 m.
During the works air temperature would go down to -45 ºС

Site №1

Coal

- A coal horizon detected on Site №1.
- The coal horizon is monoclinal, dipping at around 6 degrees.
- The coal horizon is rising along the profiles from their beginning to the end.
- The horizon roof is smooth, stable, well traced throughout each profile.
- The horizon bottom is uneven, modified by a series of wavy irregularities of up to 10 m vertically and 25-30 m along the strike.
- Thus, the horizon thickness fluctuates within a wide range and is 20 m on average (see Profiles 2-4).
- The georadar sections carry data on geological boreholes drilled close to the profiles.
- The coal horizon is modified by a breaking damage of discharge observed on Profile №1, at around 225 m.

Legend:
1 – airborne noise (Power lines, reflections from walls);
2 – dipping angle;
3 – objects (dead ground, sandstone) of various solidity;
«orehole №2032
a – claystone, sandstone (alternation);
b – sandstone;
c – coal;
d – black claystone. Site №1, georadar section №1

Borehole №2032

Fracture plane

Site №1, georadar section №1

- An extensive normal fault, filled with sedimentary rocks, is registered in the eastern part of the site (in the beginning of the profiles).

The vertical displacement is around 30-40 m.

- Orientation of lateral deflection plane: south-east – north-east.

- Waste rock layers are registered in the upper part of geological section, differing from coal mass in rigidity.

- Obtained data is highly informative, well-detailed, and shows the position and shape of the coal horizon.

Legend:

1 – Airborne noise (electric transmission lines, reflections from walls, etc.);
2 – reclined bedding angle layer
3 – objects (dead ground, sandstone) of different rigidity;
Borehole №2050:
a – claystone, sandstone (alternation);
b – sandstone;
c – coal;
d – black claystone

Borehole №2050

Site №1, georadar section №2

Determined (registered) fracture plane

Borehole №2059

Borehole №2059: b – sandstone; c – coal.

Site №1, georadar section №4

Wavy irregularities in the rock formation bottom filled with coal deposits