. The failure envelope also has a cohesion intercept as shown in Fig. The CBR values of gravelly soils range from 20% to 80%. Compacted soil also tends to be more cohesive compared to looser soil types. USCS Soil-class Description Cohesion (kPa) Friction angle (°) GW well-graded gravel, fine to coarse gravel 0 40 GP poorly graded gravel 0 38 GM silty gravel 0 36 GC clayey gravel 0 34 GM-GL silty gravel 0 35 GC-CL clayey gravel with many fines 3 29 SW well-graded sand, fine to coarse sand 0 38 SP poorly graded sand 0 36 SM silty sand 0 34 Print. The cohesion intercept is a term used in describing the shear strength soils. These values can be calculated when is known or they can be looked up in Terzaghi's Bearing Capacity Factor Table 3.1 page 87. the "Pedon Horizon Human Artifacts" tables of the NASIS database. • This occurs well-past peak shear strength… Unconfined Compressive Strength, S uc, can be determined in the laboratory using the Triaxial Test or the Unconfined Compressive Strength Test. Values for cohesion and angle of internal friction for these soil types as well as soils encountered by the Pathfinder and MER rovers are given in Table 1. Soil Types Based on Stress History: Shear strength parameters of cohesive soils are greatly affected by the stress history . Average SPT values for the top metre of sand are in the range N = 22 − 41; a conservative average value of N = 25 will be assumed for determining the allow-able bearing pressure. The BS 8004-1986 values are expanded by Tomlinson which includes indicative cohesive strengths and an indication of how wider foundations affect the allowable bearing capacities of cohesive soils. • When soil has sheared significantly (i.e. . No generalized values for safe bearing capacities can be given for these types of soils. In soils, true cohesion is caused by following: Electrostatic forces in stiff overconsolidated clays (which may be lost through weathering); Cementing by Fe 2 O 3, Ca CO 3, Na Cl, etc. Relationship between soil cohesion and shear strength Thereafter, the soil-water characteristic curves (SWCCs) for 15 cohesive soils based on Fredlund and Xing's model were generated by . To determine the value of cohesion (c) and angle of internal friction (ϕ) unconsolidated undrained triaxial test was performed according to IS: 2720 (part-11) . while the values obtained for cohesive soils from the equations are . Soil Mechanics and Classification