Wall-Friction Support of Vertical Loads in Submerged Sand and Gravel Columns

doi:10.2172/1234608

GSTDTAP > 地球科学

DOI	10.2172/1234608
报告编号	LLNL--TR-676586
来源ID	OSTI ID: 1234608
	Wall-Friction Support of Vertical Loads in Submerged Sand and Gravel Columns
	Walton, O. R.; Vollmer, H. J.; Hepa, V. S.
	2015-08-25
出版年	2015
页数	18
语种	英语
国家	美国
领域	地球科学
英文摘要	Laboratory studies of the âfloor-loadsâ under submerged vertical columns of sand and/or gravel indicate that such loads can be approximated by a buoyancy-corrected Janssen-silo-theory-like relationship. Similar to conditions in storage silos filled with dry granular solids, most of the weight of the sand or gravel is supported by wall friction forces. Laboratory measurements of the loads on the floor at the base of the water-filled columns (up to 25-diameters tall) indicate that the extra floor-load from the addition of the granular solid never exceeded the load that would exist under an unsupported (wide) bed of submerged sand or gravel that has a total depth corresponding to only two column-diameters. The measured floorloads reached an asymptotic maximum value when the depth of granular material in the columns was only three or four pipe-diameters, and never increased further as the columns were filled to the top (e.g. up to heights of 10 to 25 diameters). The floor-loads were stable and remained the same for days after filling. Aggressive tapping (e.g. hitting the containing pipe on the outside, manually with a wrench up and down the height and around the circumference) could increase (and occasionally decrease) the floor load substantially, but there was no sudden collapse or slumping to a state without significant wall friction effects. Considerable effort was required, repeatedly tapping over almost the entire column wall periphery, in order to produce floor-loads that corresponded to the total buoyancy-corrected weight of granular material added to the columns. Projecting the observed laboratory behavior to field conditions would imply that a stable floor-load condition, with only a slightly higher total floor pressure than the preexisting hydrostatic-head, would exist after a water-filled bore-hole is filled with sand or gravel. Significant seismic vibration (either a large nearby event or many micro-seismic events over an extended period) would likely be necessary before the full (buoyancy-corrected) weight of the sand and/or gravel would be âdeliveredâ to the bottom of the submerged column.
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来源平台	US Department of Energy (DOE)
引用统计
文献类型	科技报告
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/7101
专题	地球科学
推荐引用方式 GB/T 7714	Walton, O. R.,Vollmer, H. J.,Hepa, V. S.. Wall-Friction Support of Vertical Loads in Submerged Sand and Gravel Columns,2015.