Laserfiche WebLink
Engineers and Geologists <br />fragments were not included in the statistical analysis due to pro- <br />bable sample inaccuracies. The samples were grouped furtheriusing <br />laboratory analysis into cohesive materials and cohesionless mat- <br />erials. Standard Penetration Tests versus depth charts were constr- <br />ucted for each type of material after correcting the Standard <br />Penetration Test blow counts for overburden pressures. <br />A best fit straight line approximation for the distribution of the <br />cohesive type soil was determined using linear regression analysis <br />(refer to Figure 9). It was found that the mean value for sample <br />distribution for the cohesive soils group is equal to 14.4. The stan- <br />dard deviation is equal to 3.7 and the variance is equal to 13.2. Total <br />number of entries for the sample size is 27. <br />Using two tailed confidence coefficients for 95`S confidence level, <br />values for the Standard Penetration Tests of this interval for cohesive <br />soils were obtained. These values for the Standard Penetration Tests <br />are equal to 13 and 16. Using this information and Figure 8, the cor- <br />relation was obtained between the lower value of the Standard Penetration <br />Test and the cohesive shear strength parameter C. The Standard <br />Penetration Test value is compared to the energy input (sampling device) <br />and the charts described by Winterkorn and Fang (Bibliography Reference <br />Pdo.7), to determine the cohesion value for a given Standard Penetration Test <br />resistance value This value is equal to 1750 pounds per square foot <br />(854.4 grams per square centimeter). This method of determining shear <br />strength parameters is conservative due to the fact that the lower limit <br />value of the confidence interval has been used to determine the cohesive <br />shear strength parameter. <br />For cohesionless type soils using two tailed confidence coefficients <br />for the 95% confidence level was obtained for the Standard Penetration <br />Tests conducted in the field. The range of values of the Standard <br />-8- <br />