INS 332E Foundation Engineering I Homework I 25.02.2014 Problem 1 An SPT test has been performed with a standard sampler at the following depths in a deep silty sand layer. The energy ratio can be assumed as 45%. The blow counts reported are listed below. The water table is at 12m from the ground surface. The average dry and the saturated unit weights of the soil are γn= 19 kN/m3 and γsat=21.2 kN/m3 respectively. Assume that borehole and rod length corrections are CB = CR =1. a. b. c. d. e. Determine the field SPT number (Nfield) for each test data point. Plot the variation of Nfield values with depth. Using the proper correction factors, calculate the corrected SPT number, (N1)60 for each test data point. Plot the variation of (N1)60 with depth. Compare the two plots and identify the soil profile according to their consistency or relative density using the correlations between SPT-N and soil parameters. SPT Depth (m) Soil type 0-15 cm 15-30 cm 30-45 cm 3.00 3 2 6 Sand 4.50 4 2 2 Sand 6.00 4 5 7 Sand 7.50 2 5 15 Sand 9.00 3 6 6 Sand 10.50 7 8 5 Sand 12.00 9 8 7 Sand 13.50 5 12 10 Sand 15.00 8 14 12 Sand 16.5 15 18 21 Silty fine sand 18.0 13 13 24 Silty fine sand 19.5 10 14 15 Silty fine sand 21.0 15 14 15 Silty fine sand 22.5 9 15 16 Silty fine sand 24.0 14 20 24 Silty fine sand Problem 2 a) Plot the cone penetration test data (CPT) including the friction ratio FR. b) Indicate the soil classification by depth c) Estimate angle of shearing resistance of the soil (φ) at depth 7.5m using the graph given. Depth (m) 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 qc (MPa) 1.86 1.16 2.28 0.29 0.38 0.40 6.90 9.20 8.45 9.50 qs (kPa) 22.02 28.72 24.89 12.44 15.32 14.74 28.72 26.81 43.09 34.60 fr (%) Soil Classification Note: * Assume an average γ = 16.5 kN/m3 to GWT at depth 3m, and γsat = 20 kN/m3 for below GWT Due on 18.03.2014 Correlation between qc, fr and the type of soil ( Robertson and Campanella -1983) Correlation between peak friction angle and qc (Robertson and Campanella -1983)