Wonder Fissure: Usage Manual: Hole Design For Concrete

Hole Design Parameters for Concrete

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 concrete 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.

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

General Concrete

When vertical drilling is difficult, drill horizontal holes with some slope.

d 32 - 35 mm
1½ " - 1¾ "
L 40 - 60 cm
1' 4" - 2'
D 70% of Height

Reinforced Concrete

d and L depend on both quantity and shape of the reinforced steel.

d 35 mm 38 - 44 mm
1 3/8" 1 ½" - 1 ¾"
L 20 - 25 cm 30 - 40 cm
8" - 10" 1'-1'4"
D 90% of Height

Thin Concrete

(1) Square Arrangement
d 32 - 38 mm
1 ¼" - 1 ½"
L 25 - 30 cm
10" - 1'
D Almost Wall Thickness

Crack width of the front row is opened much larger than that of the behind rows.

(2) Avoid diagonal crack
d 32 - 38 mm 25 mm 32 - 38 mm
1 ¼"-1 ½" 1" 1 ¼" - 1 ½"
L 25 - 30 cm 10 cm 10 - 15 cm
10" - 1' 4" 4"-6"

The curvature at corner (R) should be more than 15 cm (6').

(3) Splitting of Wall
d 38 - 44 mm
1 ¼" - 1 ½"
L 25 - 30 cm
10" - 1'
(4) Splitting of Slab
d 38 - 44 mm
1 ½" - 1 ¾"
L 25 - 30 cm
10" - 1'
(5) Establishment of free surfaces
d 38 - 44 mm
1 ½" - 1 ¾"
L 25 - 30 cm
10" - 1'

Instead of Burn Cut, cross drilling may be used to establish the free surface for wall case.

Mass Concrete

  Concrete Reinforced Concrete
d 38 - 51 mm 38 - 44 mm
1 ½" - 2" 1 ½" - 1 ¾"
L 50 - 90 cm 40 - 60 cm
1'8" - 3' 1'4" - 2'

Pile Foundation



d 38 - 44 mm
1 ½"-1 ¾"
L1 20 cm
8"
L2 20 - 25 cm
8" - 10"

Thick Wall

Cracks propagate along wall face

d 38 - 44 mm
1 ½" - 1 ¾"
L 30 - 60 cm
1' - 2'

When perpendicular cracks to wall face are necessary:

Add a reliever hole. Spacing may be 10 cm (4') through 20 cm (8').

Drill larger diameter holes

Pier / Bridge / Foundation

Drilling depends on a shape of structure and a circumstance.

(1) Making of large block; Secondary breaking with large rock breaker

(2) Making of small pieces; Drilling is only from one side.

(3) Wall is very high; Vertical drilling is difficult

(4) Foundation is thick, Secondary breaking with large rock breaker.

Zone Demolition

(1) Staggered Arrangement (Pillar)
d 38 - 44 mm
1 ½" - 1 ¾"
L 30 - 40 cm
1' - 1'4"
D 90% of Width or Height
(2) X Figure Arrangement (Pillar, Wall)
d 38 - 44 mm
1 ½" - 1 ¾"
L 30 - 40 cm
1' - 1'4"
D 90% of Width or Height
(3) Cross Drilling (Beam)
d 38 - 44 mm
1 ½" - 1 ¾"
L 30 - 40 cm
1' - 1'4"
D 90% of Width or Height

Delayed Filling

Fill in (1) holes then (2) holes after delaying (Refer to Figures 1, 2, and 3). This can be applied for controlling of a crack direction (See Bellow).

Figure 1: Splitting of Large Boulder
d 32 - 35 mm 44 - 51 mm
1 ¼" - 1 3/8" 1 ¾" - 2"
L 30 - 40 cm 60 - 90 cm
1' - 1'4" 2' - 3'
D 70% of Height
Figure 2: Trenching and tunneling of Rock
d 38 - 51 mm
1 ½" - 2"
L 30 - 60 cm
1' - 2'
D 1 - 1.8 m
3' - 6'
θ 45°-60°

Reliever holes are necessary when trench is deep

Repeat the same procedure for deeper case

Figure 3: Mass Concrete
  Concrete Reinforced Concrete
d 38 - 51 mm 38 - 44 mm
1 ½" - 2" 1 ½" - 1 ¾"
L 50 - 90 cm 40 - 60 cm
1'8" - 3' 1'4" - 2'