PE-01-Subsurface-Exploration

PE-01-Subsurface-Exploration - 01- Subsurface Exploration...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
10 01- Subsurface Exploration *01. Find the required number of borings and their depth for a site. *02. Propose the number of samples from a geotechnical profile. *03. Which sampling method disturbs the soil the least? *04. Quiz. Which method provides the least disturbed sample? *05. Correcting the SPT for depth and sampling method. *06. Three methods used for SPT depth corrections. *07. SPT corrections with depth under a mat foundation. *08. The RQD or fractured percentage of a rock sample. *09. The Shear-vane test determines the in-situ cohesion. *10. Use the SPT to predict engineering parameters. *11. Reading a soil boring log. *12. Reading a soil boring log. *13. Using a boring log to predict soil engineering parameters. *14. Estimate the shear strength of a soil from the CPT. Symbols used in Subsurface Exploration C B STP correction factor for the boreholes diameter. C R STP correction factor for the rod length. C S STP correction factor for the sampler type used. c u Soil’s un-drained cohesion. D f Depth of the foundation’s invert. E m The efficiency of the STP hammer. N The “raw” value of the STP (as obtained in the field). p o The original vertical stress at a point of interest in the soil mass. S The number of stories of a building. SPT Stands for Standard Penetration Test” . N 60 Corrected STP assuming 60% efficiency performance in the field. N 70 Corrected STP assuming 70% efficiency performance in the field. Correction factor for the shear vane test.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
11 *Exploration–01. Find the required number of borings and their depth. (Revised: Aug. 09) A four-story reinforced concrete frame office building will be built on a site where the soils are expected to be of average quality and uniformity. The building will have a 100 ft x 120 ft footprint and is expected to be supported on spread footing foundations located about 3 ft below the ground surface. The site appears to be in its natural condition, with no evidence of previous grading. Bedrock is 100-ft below the ground surface. Determine the required number and depth of the borings. Solution: A reinforced concrete building is heavier than a steel framed building of the same size. Hence, the design engineer will want soil conditions that are at least average or better. Table-1 below suggests one boring for every 3,000 ft 2 of building footprint area. Since the total footprint area is 100 ft x 120 ft =12,000 ft 2 , use four borings . From Table-2 the minimum depth required for the borings, 15 S 0.7 + D = 15(4) 0.7 + 3 = 43 ft . Most engineers want one of the borings to go to a slightly greater depth to check the next lower stratum’s strength. Table-1
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 19

PE-01-Subsurface-Exploration - 01- Subsurface Exploration...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online