Wonder Fissure: Usage Manual: Hole Design For Rocks

Hole Design Parameters for Rocks

The spacing, length (or depth) angle and diameter of the drill holes will be determined by the properties of the material to be removed and may require adjustment when areas of different hardness are encountered in the same rock body.

Following are examples of hole patterns for different situations for usage on rocks and boulders and are to be used as a guide only.

It is recommended that a test pattern be trialled to ascertain the quality of the material to be demolished.

Legend
Symbol Key
d Hole Diameter
L Hole Space
D Hole Depth
θ Angle
Hole Direction

General Concepts For Breaking Of Boulders



d 38 - 44 mm
1 1 / 2 "- 1 3 / 4 "
D 70 % of Height
(1) Soft Rock
(Tensile Strength: < 60 kg/cm² : 85 psi)
(2) Middle Hard Rock
(Tensile Strength: 60 - 100 kg/cm² : 80 - 140 psi)
(3) Hard Rock
(Tensile Strength: > 100 kg/cm² : 140 psi)

Underground Excavation

d 38 - 44 mm
1½ "- 1¾ "
L 30 - 60 cm
1 '- 2 '
D Shown in Figure
d 38 - 51 mm
1½ "- 2 '
L 60 - 90 cm
2 '- 3 '
D 90 % of Height

Splitting of Large Boulders

d 32 - 35 mm 44 - 51 mm
1¼ "- 1 3/8 " 1¾ " - 2 "
L 30 - 40 cm 60 - 90 cm
1 '- 1 ' 4 " 2 '- 3 '
D 70 % of Height

Cutting Into Slabs

d 32 - 35 mm 44 - 51 mm
1¼ "- 1 3/8 " 1¾ " - 2 "
L 20 - 30 cm 40 - 50 cm
8 "- 1 ' 1'4 "- 1'8"
D 90 % of Height

Breaking of Virgin Rock

The toe should be drilled at closer hole spacing and successively broken from the front row. No drilling will cause poor breakage.

The front holes (up to the sixth row) may be simultaneously filled in. It is more effective for removal to fill in one hole and then  each two rows (2, 3) after a delay of 6 - 20 hours.

d 44 - 51 mm
1¾ " - 2 "
L1 30 - 40 cm
1 '- 1'4"
L2 60 - 90 cm
2 '- 3 '
D Add 5 % of Height
80 °- 90 °

Trenching And Tunneling

d 38 - 51 mm
1½ " - 2 "
L 30 - 60 cm
1 '- 2 '
D 1 - 1.8 m
3 '- 6 '
45 °- 60 °
Reliever holes are necessary when trench is deep
Repeat the same procedure for deeper case 
d 38 - 51 mm
1½ "- 2 '
L1 40 - 60 cm
1'4 "- 2 '
L2 30 - 40 cm
1 '- 1'4"
D 1 - 1.8 m
3 '- 6 '
d 38 - 44 mm
1½ "- 1¾ "
L 30 - 60 cm
1 '- 2 '