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4. (a) Briefly define the following: (40 marks) (i) Desk study (ii) Trial pits (iii) Borehole (iv) Standard Penetration Test (b) A borehole is drilled to a depth of 3.5 m in a sand. The water table was found at a depth of 2.0 m. The unit weight of the sand is 18 kN/m2 and the saturated unit weight is 20 kN/m². During the boring the Standard Penetration Test (SPT) was conducted and the field N-values are given in the table below. The energy ratio for the equipment was reported to be 45. Depth (m) 1,0 to 1,5 2,0 to 2,5 3,0 to 3,5 N 9 13 (60 marks) 27 You are asked to: (i) (ii) Estimate the corrected (N1)60 Derive the value of using the Hatanaka and Uchida (1996) correlation given below. Use the following equations and tables (from EC7) to answer the question:
Er (N1)60 = ExλX Cν ΧN 60 98 Cn = Loo Values of the correction factor Cy larger than 2,0 and preferably 1,5 should not be applied. 20. (N1) 60 + 20 (Hatanaka & Uchida, 1996) Table A.1 -Correction factors in sands due to rod length Rod length below the anvil m Correction factor 2 >10 6 to 10 4 to 6 1,0 0.95 0.85 3 to 4 0.75 Total marks for question 4 100 marks