CRT-Hole Closure |
| |
| Authors: | Thomas E Noce Thomas L Holzer |
| |
| Institution: | Thomas E. Noce;(Geologist, U.S. Geological Survey, 345 Middlefield Rd., MS977, Menlo Park, CA 94025;; 329–4861;fax 329–5163) has a B.S. in geology from Mesa State College, Grand Junction, Colorado. He has 10 years experience at the USGS working on earthquake hazards. His current research is directed toward using CPT technology to define areas of potential liquefaction and high shaking intensity in areas of seismic risk. Thomas L. Holzer;(Engineering Geologist, U.S. Geological Survey, 345 Middlefield Rd., MS977, Menlo Park, CA 94025) has a B.S.E. in geological engineering from Princeton University, an M.S. in hydrology from Stanford University, and a Ph.D. in geology from Stanford University. He has more than 27 years experience at the USGS working on land subsidence and seismic hazards. He is also a consulting professor at Stanford University. His current research interests include geotechnical characterization of geologic materials for seismic hazards mapping. |
| |
| Abstract: | The long-term stability of deep holes 1.75 inches. (4.4 cm) in diameter by 98.4 feet (30 m) created by cone penetration testing (CPT) was monitored at a site in California underlain by Holocene and Pleistocene age alluvial fan deposits. Portions of the holes remained open both below and above the 28.6-foot (8.7 m)-deep water table for approximately three years, when the experiment was terminated. Hole closure appears to be a very slow process that may take decades in the stiff soils studied here. Other experience suggests holes in softer soils may also remain open. Thus, despite their small diameter, CPT holes may remain open for years and provide paths for rapid migration of contaminants. The observations confirm the need to grout holes created by CPT soundings as well as other direct-push techniques in areas where protection of shallow ground water is important. |
| |
| Keywords: | |
|
|
