Skin Friction of the Micropile Root
Reference values of limit skin friction (recommended by the authors)
Soil | Skin friction [kPa] |
soft clay | 40 - 60 |
stiff clay | 65 - 85 |
solid clay | 130 - 170 |
sand naturally wet, loose | 110 - 150 |
sand naturally wet, medium dense | 140 - 180 |
sand naturally wet, dense | 170 - 230 |
aquiferous sand, loose | 80 - 130 |
aquiferous sand, medium dense | 120 - 160 |
aquiferous sand, dense | 160 - 200 |
sandy clay, soft | 50 - 70 |
sandy clay, stiff | 75 - 95 |
sandy clay, solid | 125 - 165 |
clayey sand, wet, loose | 90 - 135 |
clayey sand, wet, medium dense | 135 - 165 |
clayey sand, wet, dense | 150 - 170 |
clayey sand, aquiferous, loose | 80 - 105 |
clayey sand, aquiferous, medium dense | 90 - 130 |
clayey sand, aquiferous, dense | 115 - 155 |
Values of limit skin friction according to DIN 4128
Soil | Average limit skin friction | |
piles in compression [kPa] | piles in tension [kPa] | |
medium to coarse-grain sand | 200 | 100 |
sand and gravel sand | 150 | 80 |
cohesive soils | 100 | 50 |
Recommended parameters of anchor roots (Mišove, Klein, Inženýrské stavby 5/1986)
Type of support of micropile in head | Final grouting press. [MPa] | Number of groutings | Root diameter [mm] | Root length [m] | Skin friction [kPa] |
bedrock | - | 0 | 120 | 5 - 3 | 1000 - 1600 |
semirock | 0.5 - 3.0 | 0 - 1 | 120 - 220 | 7 - 3 | 300 - 1000 |
gravel, injectable soils | 1,0 | 1 - 2 | 250 - 400 | 7 - 5 | 250 - 320 |
gravel, non-injectable soils | 2.0 - 4.0 | 1 - 2 | 280 - 350 | 7 - 5 | 230 |
medium and fine-grain sand | 1.5 - 4.0 | 2 - 3 | 220 - 350 | 12 - 7 | 150 - 180 |
cohesive stiff and solid soils | 1.5 - 3.0 | 1 - 3 | 200 - 280 | 17 - 8 | 130 - 190 |
cohesive solid to rigid plastic soils | 1.0 - 2.5 | 2 - 3 | 150 - 400 | 20 - 9 | 100 - 130 |
cohesive soft plastic soils | 0.5 - 2.0 | 3 - 4 | 300 - 450 | 27 - 13.5 | 50 - 70 |