Dynamic Bolts & Products - Dynamic OMEGA-BOLT®
The Dynamic OMEGA-BOLT® is an evolution of the DSI Underground OMEGA-BOLT® a high pressure inflatable friction bolt, used to secure a great variety of ground conditions, subjected to different stress conditions. All OMEGA-BOLT® systems are based on a steel tube, longitudinally formed in its typical omega (Ω) shape and made pressure tight by welded bushings on each end. The Dynamic OMEGA-BOLT® adds an extra steel element that is placed inside the omega shaped profile and welded to the upper and lower bushings. This extra element provides the capacity to absorb a large quantity of elastic energy in case of rock bursts as well as additional loading capacity in static conditions.
The Dynamic OMEGA-BOLT® has been developed to provide safe, effective, and fast rock support in mines or tunnels where high stress in the rock mass can create a sudden release of energy (rock bursts). These micro-seismic events are similar to an explosion, able to crush rock and eject fragments into the excavated drifts, and they represent a great danger to miners and equipment. In these cases, there is a need of a “dynamic” rock reinforcement system, meaning a series of elements able to dampen the explosion-like phenomenon and still able to retain the crushed rock from falling down. The Dynamic OMEGA-BOLT® is a fundamental part of modern dynamic reinforcement; it is able to absorb 35 [kJ] of energy and still retain a residual loading capacity in the range of 70 [kN].
|Dynamic OMEGA-BOLT® Type 35 [kJ]||Unit||Design Parameters/|
|Steel: yielding/tensile stress||[MPa]||350/500||-|
|Steel elongation (A5)||[%]||10||15 1)|
|Steel sheet thickness (inner/outer profiles)||[mm]||2||-|
|Steel cross section, outer profile||[mm²]||326||-|
|Steel cross section, inner profile||[mm²]||154||-|
|Bolts mass per meter||[kg/m]||3.75||-|
|Bolt diameters: installation profile, upper bushing, lower bushing||[mm]||36/38/41||-|
|Diameter fully expanded profile||[mm]||54||-|
|Recommended drill hole diameter||[mm]||45 -48||-|
|Static ultimate tensile load-bearing capacity||[kN]||163 + 77 = 240||-|
|Static shear resistance 2)||[% UTS]||-||85 - 90|
|Dynamic energy absorption (1 drop)||[kJ]||-||35 1)|
|Plate displacement (1 drop) 3)||[mm]||-||350 1)|
1) CANMET-MINING (Canada) laboratory tests, report 2016. Split tube test configuration
2) SINTEF (Norway) laboratory tests, 2014
3) On a 2.4m long bolt
All values are subject to change
The dynamic behavior of the Dynamic OMEGA-BOLT® has been tested by a qualified Canadian public institution. The results prove the bolt’s capacity to absorb 35 [kJ].
This value is higher than the quantity of energy which is normally considered as the reference value for micro-seismicity risk in large, deep underground mines (i.e. 30 [kJ]).