Problem 7-7 The results of SPT tests performed with an automatic trip hammer using the standard ASTM split spoon sampler with a liner are shown in the following table. The borehole diameter was within the recommended range. The soil profile consists of a normally consolidated sand with unit weight equal to 20 kN/m. The water table is located at 4.5 m below the ground surface. Estimate the relative density DR and the peak friction angle, at depths where SPT measurements are available. Use Eq. (7.6) with Eq. (7.8) to estimate DR, and use Fig. 7-14 to estimate , You may use the following table to guide your calculations. Depth (m) Nspt Ch Cr N60 av (kPa) DR op (deg) st 4 5 6 25 30 35 =2 De 100% 7.8=7 C- CH Noo At BC/Ov Ko PAL 0.5 1.0 o'y I PA 5 2.0 2.5 3.0 0 eee = 25 6=30 = 35 10 20 30 $ = 40 40 N60 = 50 = 45 50 60 70 80 Figure 7-14 Correlation between SPT blow counts and peak friction angle 'p' (Modified after De Mello 1971) diw bu sib isting tadi thus od vem abor