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Square arches of V-25 section shape are designed to support roadways of square shape.

Idea to design arches was created in cooperation with mining industry and is the answer to coal mines requirement of square shape arches to gain large width of roadway in order to better use roadways cross – section.
Arches are use for installation faces and for bolting roadways in case of crossing worse geological conditions.

Technical data

Square arches consist of elements made of V-25 section shape joined by “overlapping” By SD25 or SDO25 clamps.

Series of types according to draw. No 1 is to suport square roadways of the following cross - sections:
- height : from 2200 mm to 4000 mm
- width : from 3200 mm to 7500 mm

 

 
 
 

 

Quantity of elements for one arch is 5 or 6 depending on height.

Roof beam is made of one or two straight elements. Rib part is made of two elements of different curvature but straight along the overlapping length in order to make joining possible despite different radius.
Overlapping for all arches is the same and is 500mm.
Different arch height is achieved by changing the length and radius of rib element. Different arch width is achieved by using one or two straight elements of roof beam.

Series of types according to draw. No 2 is to support square roadways of the following cross - section :
height : from 2200 mm to 4000 mm
- width : from 3200 mm to 7500 mm

 

 
 

 

Roof beam is made of two elements which are straight along the roof and overlapping part.
Overlapping length between roof and rib elements is 500mm, overlapping length between Roof elements is from 600 to 1500mm.
Different arch height is achieved by changing the length and radius of rib element.
Different arch width is achieved by using one or two straight elements of roof beam.

To increase capacity it is recommended secondary bolting by one or two pair of bolts.

Arnall type arches were used In coal mine "Jankowice", "Chwałowice", "Staszic", ,"Ziemowit", "Silesia" and ,"Budryk".


Square arches Arnall Type of V25 section shape has certificate No B/1025/IV/2013 issued by Główny Instytut Górnictwa in Katowice