Maro Publications

Natural Structures

Notes

*7/24/2012

Maro Topics

Comments

Patents with Abstracts

Structures

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Notes

Natural structures are those structures made with a large amount of natural materials such as soil, stones or plant material.  (RDC 7/24/2012)

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“Bridges, culverts, overpasses, and the like, are traditionally constructed of expensive and environmentally incompatible steel structures, reinforced concrete structures, plastic structures and the like. For instance, bridges are usually constructed using concrete and/or steel foundations supporting pre-stressed concrete spans or suspended concrete and/or steel spans extending between the supports. Culverts used in road construction, often in stream beds, are usually constructed of concrete, corrugated steel or corrugated plastic pipes or pipe arches. Open bottom steel and concrete arch structures are usually constructed on concrete or steel footings. Installation of these footings is often a significant component of the cost of the arch installation and often involves excavation below the level of the stream bed. This can result in damage to the stream and introduction of sediment to the stream or result in costly mitigation techniques to prevent or limit the extent of damage and sedimentation. Snowsheds and avalanche sheds used in highway and railway construction are usually constructed as concrete and/or steel bridge-like structures, often in the form of a box or arch. Such structures must be designed to accommodate large, unbalanced loads. Otherwise these rigid structures can topple and/or collapse.

A problem with concrete, corrugated metal culverts and corrugated plastic culverts is that with freeze/thaw cycles, water erosion and dynamic vehicle loads on the culverts, the soil compacted around the concrete, steel or plastic culverts can become loose and erode away, thereby leaving an uneven load distribution on the culvert. When this occurs, the uneven load distribution may be sufficient to cause the culvert to collapse. The undermining of footings supporting steel, concrete or plastic arches can result in the loss of support for the soil compacted around the arch. This can result in uneven loading on the structure and possible collapse of the structure. Then it may be necessary to close the road or railway for a period of time while the structure is repaired or replaced.

U.S. Pat. No. 6,874,974 B1, granted Apr. 5, 2005, VanBuskirk et al., discloses a novel design of reinforced soil arches which can be used to construct bridges, overpasses, snowsheds, landslide or rock fall protection structures, and the like. In particular, the patent discloses an innovative use of compacted mineral soil (clay, silt, sand, gravel, cobbles, boulders, broken rock or mixtures of any or all of the foregoing) in combination with geosynthetic reinforcement to construct a reinforced soil arch that can be used for numerous purposes. The patent also discloses a method for constructing the reinforced soil arch comprising constructing an arch utilizing a combination of layers of compacted mineral soil and reinforcement in a manner that supports both the dead load of the structure and a live load imposed on the structure. Mechanisms for securing the reinforcement and the other components together are also disclosed.”

[VanBuskirk, US Patent 8,215,869 (7/10/2012)]

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Interested!!
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(RDC 6/5/2012)

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Roger D. Corneliussen
Editor
www.maropolymeronline.com

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Copyright 2012 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 7/24/2012.