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作者 Barry, Mark A
書名 Elastic and Fracture Behaviour of Marine Sediment in Response to Free Gas
國際標準書號 9780494698754
book jacket
說明 177 p
附註 Source: Dissertation Abstracts International, Volume: 72-03, Section: B, page: 1372
Thesis (Ph.D.)--Dalhousie University (Canada), 2010
The growth and rise of biogenic gas bubbles in marine sediments is dependent on both a source of gas and the response of the sediment matrix. Currently, response of the matrix is poorly constrained and literature has reported behaviour that ranges from viscous, to plastic, to elastic. Over the last ten years our lab has worked on elastic fracture of sediment in response to gas bubble growth, with good success. This thesis aims at improving our understanding of the fracture process and testing linear elastic fracture mechanics (LEFM) over a wider range of bubble sizes, and applying the LEFM theory to other problems associated with gas-laden sediment
Bubble growth over a smaller range of sizes, up to an order of magnitude smaller than previously grown, show good correlation of bubble aspect ratio and pressure to those predicted by LEFM. Fracture behaviour was observed in sediments with porosity up to 0.85, and the elastic modulus (E) is inversely proportional to porosity. To measure the elastic behaviour of sediment a new, in situ membrane probe was developed and tested. The probe is capable of measuring continuous stress-strain and has a depth resolution of two centimeters. Coastal inter-tidal sediments tested show elastic behaviour to strains ranging from 0.005-0.03, and corresponding E's range from 50-1000 kPa
The use of LEFM combined with thin plate bending as a mechanistic model for sediment failure and pockmark formation has been employed, and is capable of explaining a variety of common observations of pockmarked areas. Increasing pockmark size with increasing thickness of sediment and the explosive release of gas that is believed to result in many pockmarks, are both explained by the mechanics model described herein
Overall, the use of elastic fracture mechanics in fine-grained marine sediments under the influence of gas bubbles and cavities has been shown to be a viable mechanism of sediment failure
School code: 0328
Host Item Dissertation Abstracts International 72-03B
主題 Physical Oceanography
Marine Geology
0415
0556
Alt Author Dalhousie University (Canada)
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