The caving/sloughing of sandy layers into drilled shafts is a common and costly phenomenon in the drilling industry. A prototype soil-testing device known as the Pneumatic In-situ Soil Caving Index Sampler (PISCIS) has been developed to test sandy layers above the water table for their propensity to cave/slough into a drilled shaft during the drilling process. The PISCIS fits down a Cone Penetration Test (CPT) hole and uses air pressure to agitate a sample off of the hole wall that is then collected and weighed. Large-scale lab testing was conducted using sand under a variety of simulated overburden pressures and fines contents. The tests were conducted with a dual purpose in mind. First, the tests confirmed the functionality of the PISCIS prototype and its ability to collect samples in a consistent and repeatable manner. Second, the tests resulted in a calibration curve that shows a very strong (nearly exponential) relationship between collected sample weight and the fines content of the test sand; higher fines contents resulted in lower collection weights. The PISCIS was designed to supplement information found in a geotechnical report with information that would specifically inform drilling contractors about potential caving/sloughing hazards found in the stratigraphy.
| Identifer | oai:union.ndltd.org:CALPOLY/oai:digitalcommons.calpoly.edu:theses-2508 |
| Date | 01 March 2015 |
| Creators | Grolle, Michael A |
| Publisher | DigitalCommons@CalPoly |
| Source Sets | California Polytechnic State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Master's Theses |
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