CABLE BOLTS

• KL-15,5, KL-15,5K

Intended use

• KL - 15,5; KL - 15,5K cable bolts are designed to be used in ground and rock reinforcement near mining excavations and in particular near workings in weak strata with lower strength or entering mining pressure zones.

Technical description

• Cable bolts are made from cable of Ø15,5 mm and 1+6 structure in accordance with PN-71/M-80236. The following types of bolt can be distinguished:

The cable lay of KL-15,5K bolt was modified to form birdcage like bulbs of 100mm in length and 26 ÷ 28 mm in diameter. This ensures a better force distribution affecting the cement grout around the cable.

When filled with grout the cages act like stiff bulbs in relation to the cement face. The bulbs remain non-cracked despite considerable forces affecting the cable as radial forces occurring in the wires, which could potentially crush the cement in the bulbs, are relatively light when compared to axial forces.

The shape of the cable considerably affects force distribution around the cable caused by cable displacement in the rock.

The bulbs cause considerable forces perpendicular to the hole wall compressing the grout and at the same time reduce compressive forces parallel to the hole axis.

Force distribution around cable bulb P1 - compressive force P2 - shearing force

As a result cage cables bolts perform better in the rock, i.e. cable displacement in the rock, caused by load intensity, is smaller when compared to plain cable.

Cable bolts should have the following mechanical properties:

• - Rm = min 1420 MPa
• - Rm = min 1620 MPa
• - Rm = min 1800 MPa

Approval tests have shown that cement grout hardening is 3 times stronger for KL-15,5K cage cable bolts than plain cable bolts, while the bolt length stays the same.

• Square washers, round profiled or flat washers are made of 8 or 10 mm metal plate, and come in sizes from 150 to 300 mm. If elements of mining equipment need to be attached, use washer plates with a side hole or an eyelet.
• Three-part clamping ring along with the bearing washer make the roof set.
• M30 tensioning sleeve and M30 nut are used to apply the initial tension to the bolt.

Technical data

Installation procedure

• Drill holes of appropriate length and at least Ø > 25 mm for plain cable or Ø > 38 mm for cage cable bolts,
• Prepare the cable to be installed (attach a vent pipe of Ø 6 or Ø8 mm to the cable),
• Insert the cable into the hole letting 15 to 20 cm of the cable out of the hole,
• Mount and space the injection head,
• Prepare cement and water grout in the mixer,
• Inject the grout until cement wash appears in the vent tube or the air stops flowing out,
• After 24 hours fix the bearing washer, M30 sleeve and nut (if included) and the clamp,
• If the bolt comes with M30 tensioning sleeve and M30 nut, the initial tension of at least 30kN should be applied using a torque wrench with the torque of at least 60 Nm.

NOTE: Installation procedure may differ when adhesives or other equipment is used to install the bolt.