If required to use Texas Cone Penetration (TCP) data to evaluate capacity of existing bridges, use the charts and correlations from this Appendix to determine skin friction and point-bearing capacity for drilled shafts and piling. Use Figure A1-2 to determine allowable skin friction for soil softer than 100 blows/12 in. Select the curve based on the description of the soil type.

Use the CH curve in clay soil identified as high-plasticity, or fat clay. Use the CL curve in clay soil identified as low-plasticity, or lean clay. In clay soil, use the CL curve if no specific identification is provided regarding plasticity. Use the SC curve for soil described as either sandy clay or clayey sand. Use the OTHER curve for soils described as silt, sand, gravel or any layers not fitting into one of the previous designations.

Use figure A1-1 to correlate TCP test results to angle of internal friction of cohesionless soils.