Updating Bearing Capacity – SPT Graphs - Maryland State Highway ...

TABLE 2.1 Angle of Friction from Different EquationsN 60 Eq. 2.1 Eq. 2.2 Eq. 2.32 27.70 27.604 28.29 28.206 28.88 24.49 28.808 29.46 25.95 29.4010 30.15 27.25 30.0012 30.62 28.42 30.6014 31.19 29.49 31.2016 31.76 30.49 31.8018 32.33 31.43 32.4020 32.88 32.32 33.0022 33.44 33.16 33.6024 33.98 33.97 34.2026 34.53 34.75 34.8028 35.08 35.49 35.4030 35.61 36.21 36.0032 36.15 36.91 36.6034 36.08 37.58 37.2036 37.20 38.24 37.8038 37.72 38.87 38.4040 38.24 39.49 39.0042 38.75 40.09 39.6044 39.25 40.69 40.2046 39.76 41.27 40.8048 40.26 41.83 41.4050 40.75 42.39 42.002.4 Cohesion of Cohesive SoilsThe SPT N-value for a given clay may vary significantly with seasonal fluctuations in thewater table. Thus, the values may fall short of providing information on the characteristics of theclay, mainly its strength. There are correlations that estimate the undrained shear strength ofclay as a function of the SPT N-value. These correlations are not as meaningful for sensitive andmedium to soft clays where effects of disturbance during sampler penetration may cause alowering in the SPT N-value.2-4