Table 9.3 Fill Factors for Hydraulic Hoe Buckets Moist loam/sandy clay Sand and gravel Rock-poorly blasted Rock-well blasted Hard, tough clay *Percent of heaped bucket capacity. Reprinted courtesy of Caterpillar, Inc. Material Fill Factor* (%) 100-110 95-110 40-50 60-75 80-90 Table 9.4 Excavation Cycle Times for Hydraulic Crawler Hoes under Average Conditions* Bucket Size (cy) <1 Load Bucket (sec) 5 Swing Loaded (sec) Dump Bucket (sec) Swing Empty (sec) Total Cycle (sec) 4 2 3 14 1−1½ 6 4 2 3 15 2-2½ 6 4 3 4 17 3 7 5 4 4 20 312 7 6 4 5 сл 22 4 5 7 7 6 7 4 5 22 4 *Depth of cut 40 to 60% of maximum digging depth; swing angle 30 to 60 degrees; loading haul units on the same level as the excavator 100 6 24

Three groups of students from the Geotechnical Engineering class collected soil-aggregate samples for laboratory testing from a recycled aggregate processing plant in Palm Beach County, Florida. Three samples, denoted by Soil A, Soil B, and Soil C, were collected from three locations of the aggregate stockpile, and sieve analyses were conducted (see Figure 2.35). (a) (b) Figure 2.35 (a) Soil-aggregate stockpile; (b) sieve analysis (Courtesy of Khaled Sobhan, Florida Atlantic University, Boca Raton, Florida) a. Determine the coefficient of uniformity and the coefficient of gradation for Soils A, B, and C. b. Which one is coarser: Soil A or Soil C? Justify your answer. c. Although the soils are obtained from the same stockpile, why are the curves so different? (Hint: Comment on particle segregation and representative field sampling.) d. Determine the percentages of gravel, sand and fines according to Unified Soil Classification System.

Repeat Problem 2.8 using the following data. 2.8 The following are the results of a sieve and hydrometer analysis. a. Draw the grain-size distribution curve. b. Determine the percentages of gravel, sand, silt and clay according to the MIT system. c. Repeat Part b according to the USDA system. d. Repeat Part b according to the AASHTO system.

Since laboratory or field experiments are generally expensive and time consuming, geotechnical engineers often have to rely on empirical relationships to predict design parameters. Section 6.6 presents such relationships for predicting optimum moisture content and maximum dry unit weight. Let us use some of these equations and compare our results with known experimental data. The following table presents the results from laboratory compaction tests conducted on a wide range of fine-grained soils using various compactive efforts (E). Based on the soil data given in the table, determine the optimum moisture content and maximum dry unit weight using the empirical relationships presented in Section 6.6. a. Use the Osman et al. (2008) method [Eqs. (6.15) through (6.18)]. b. Use the Gurtug and Sridharan (2004) method [Eqs. (6.13) and (6.14)]. c. Use the Matteo et al. (2009) method [Eqs. (6.19) and (6.20)]. d. Plot the calculated wopt against the experimental wopt, and the calculated d(max) with the experimental d(max). Draw a 45 line of equality on each plot. e. Comment on the predictive capabilities of various methods. What can you say about the inherent nature of empirical models?