Assume two construction sites: Site A and Site B. Based on the geotechnical report, the dominant soil type is GP at Site A and CL at Site B. The soil will be excavated before the installation of the foundation. Answer the following questions based on the information provided:
Q1. Check the table in Figure 2.3 in your textbook and answer the following questions:
a) Which soil categories do the soils at sites A and B fall under (coarse-grained or fine-grained)?
b) Describe what symbols of GP and CL mean.
c) Which soil type is frictional and which one is cohesive?
Q2. Answer the following questions regarding the excavation process:
a) For a shallow cut above the water table for installing the utility lines, which soil type might be able to hold itself in place without the need for support?
b) For a deep excavation, a supported system should be considered. You need as much space as possible at the site and prefer less clutter of the excavation support braces. Sort the following bracing systems starting from the most preferable bracing system: 1) Cross-lot, 2) Raker, 3) Tieback
Q3. A deep excavation will go below the water table. You need to keep the bottom of the excavation dry during the excavation. As a result, you might need a dewatering system.
a) Compare the soil permeability at sites A and B. Which one is more permeable?
b) Which site would you expect to require you plan for a dewatering system? Why?
Q4. A multi-story building will be constructed at these sites that require a soil bearing capacity of 4500 psf. To estimate the bearing capacity of the soils at sites A and B, check the table in Figure 2.6.
a) Which soil type would you expect to have a higher bearing capacity (soil at site A or B)?
b) Assume a bedrock is located in a relatively shallow depth. As a result, an end-bearing deep foundation can be constructed. What type of foundation would the structural engineer design (shallow foundation or deep foundation)? Explain your rationale.
c) Assume the bedrock is located in very great depth (not reachable). Discuss the foundation type(s) that could be designed.