Table 1. Types of foundation soils
Soil type |
Description |
I |
Rock: Natural material, with in-situ shear wave propagation velocity equal to or greater than 900 m/s, or uniaxial compressive strength of intact specimens (without fissures) equal to or greater than 10 MPa and RQD equal to or greater than 50 %. |
II |
a) Soil with Vs equal to or greater than 400 m/s in the upper 10 m, and increasing depth, or, b) Dense gravel with a dry unit weight ƒÁ_{d} equal to or greater than 20 kN/m^{3}, or greater the 95% of the maximum determined in the Modified Proctor Compaction Test, or a relative density (RD) equal to or greater than 75% ,or, c) Dense sand with an (RD) greater than 75%, or a Penetration Resistance Index N greater than 40 (standardized at the effective overburden pressure of 0.10 MPa), or a compaction degree greater than 95% of the maximum Modified Proctor value; or, d) Stiff cohesive soil, with an undrained shear strength s_{u} equal to or greater than 0.10 MPa (compressive strength q_{u} equal to or greater than 0.20 MPa) in specimens without fissures. In all cases, the requirements specified must be met, regardless of the position of the ground water level, and the minimum stratum thickness must be 20m. If the thickness above the rock is lower than 20m, the soil may be classified as type I. |
III |
a) Permanently unsaturated sand with (RD) in the range of 55 and 75%, or N greater than 20 (without standardizing at the effective overburden pressure of 0.10MPa); or, b) Unsaturated gravel or sand, with a compaction degree less than 95% of the maximum Modified Proctor value or, c) Cohesive soil with s_{u} in the range of 0.025 y 0.10 MPa (q_{u} between 0.05 and 0.20 MPa) , regardless of the ground water level; or, d) Saturated sand with N in the range of 20 and 40 (standardized at the effective overburden pressure of 0.10 MPa). Minimum stratum thickness: 10m. If the stratum thickness above the rock or soil type‡U is less than 10 m, the soil may be classified as type‡U. |
‡W |
Saturated cohesive soil with s_{u} equal to or greater than 0.025 MPa (q_{u} equal to or less than 0.050 MPa). Minimum stratum thickness: 10 m. If the stratum thickness above soil types‡T,‡Uor‡V is less than 10 m, the soil may be classified as type‡V. |