Micropiles – An Overview Micropiles – An Overview - AGC

Typical Ultimate ά bond Micropile Design Values
Soil/Rock Type
Silt & Clay (some sand)
(soil, medium plastic)
Silt & Clay (some sand)
(stiff, hard to very hard)
Sand (some silt)
(fine, loose-medium dense)
Sand (some silt, gravel)
(fine-coarse, medium-very dense)
Gravel (some sand)
(medium- very dense)
Glacial Till (silt, sand, gravel)
Medium-very dense, cemented)
Soft Shale (fresh-moderate
fracturing, little or no weathering)
Slate to Hard Shale (fresh-moderate fracturing,
little to no weathering)
Limestone (fresh-moderate fracturing,
little or no weathering)
Sandstone (fresh-moderate fracturing,
little or no weathering)
Granite and Basalt (fresh-moderate fracturing,
little or no weathering)
For Preliminary Design
Grout-to-Ground Bond Ult. Strength/Nominal Resistance, ksf (psi)
Type A Type B Type C Type D Type E
0.7-1.4
(5-10)
0.7-2.5
(5-17)
1.4-3.0
(10-21)
2.0-4.5
(14-31)
2.0-5.5
(14-38)
2.0-4.0
(14-28)
4.3-11.5
(30-80)
10.8-28.8
(75-200)
21.6-43.2
(150-300)
10.8-36.0
(75-250)
28.8-87.7
(200-609)
0.7-2.0
(5-14)
1.4-4.0
(10-28)
1.4-4.0
(10-28)
2.5-7.5
(17-52)
2.5-7.5
(17-52)
2.0-6.5
(14-45)
0.7-2.5
(5-17)
2.0-4.0
(14-28)
2.0-4.0
(14-28)
3.0-7.5
(21-52)
3.0-7.5
21-52
2.5-6.5
(17-45)
0.7-3.0
(5-21)
2.0-4.0
(14-28)
2.0-5.0
(14-35)
3.0-8.0
(21-56)
3.0-8.0
(21-56)
2.5-7.0
(17-49)
0.7-2.0
(5-14)
1.4-4.0
(10-28)
1.4-5.0
(14-35)
2.5-7.5
(17-52)
2.5-7.5
(17-52)
2.0-6.5
(14-45)
N/A N/A N/A N/A
N/A N/A N/A N/A
N/A N/A N/A N/A
N/A N/A N/A N/A
N/A N/A N/A N/A
Ref: FHWA NHI-05-039 & AASHTO LRFD 4 th Ed 2007, Interim 2008 Table C10.9.3.5.2-1