This was achieved by combining laboratory test results and a back analysis of pore water pressure time records during a period of reservoir water level fluctuations. A key aspect of the case was the correct characterization of permeability of a representative soil profile. Then, a recent case of a major landslide triggered by a rapid drawdown in a reservoir was interpreted. Field records indicate that classical undrained calculations are conservative but unrealistic. A similar analysis was performed for the upstream slope of the Glen Shira Dam, Scotland, and numerical results were compared with field measurements during a controlled drawdown. Paint drawdowns are used to measure opacity. Simple methods, such as undrained analysis and pure flow analysis, implicitly assuming a rigid soil skeleton, lead to significant errors in pore water pressure distributions when compared with coupled flow-deformation analysis. 728 subscribers This video shows the correct procedure to perform a paint drawdown using a BYK-Gardner Drawdown Bar, Drawdown Cards and Drawdown Plate.
To do that, a single slope subjected to a drawdown was first analyzed under different calculation alternatives, and numerical results were discussed. The aim of the study was to evaluate different approaches available for calculating pore water pressure distributions during and after a drawdown.
Once this evenly spread paint dries, it can be tested for a variety of properties.In this study, rapid drawdown scenarios were analyzed by means of numerical examples as well as modeling of real cases with in situ measurements. Drawdown Bar Anti-Sag Meter 3-12 mils Range 3 to 12 mils Total film width 3 3/8 inches 550.00 excl. Then the bar is placed at the top of the chart, and drawn down over the paint in order to spread it evenly along the length of the chart. Initially the desired coating is applied in a puddle on the drawdown chart. Drawdown Boards Buschman also offers a high-quality Drawdown Board that enables quality technicians to make laboratory samples of thin film coatings rapidly and inexpensively. Special sizes are available upon request. There are a multiplicity of more complicated designs including some in which the paint is already in the chart apparatus, but the bar method described above is the most commonly used. Standard laboratory drawdown rods are 0.500in x 16.00in. As with the charts, the bars have to be especially resistant to corrosion because of the corrosive nature of some coatings. The bars are generally made of stainless steel or aluminum and touch the chart at each end, while the center is slightly raised to a desired height in order to obtain the desired film thickness. These charts are necessary in the testing of any coating as they give reliable and accurate readings for any type of coating before the coating is applied to the intended material.ĭrawdown bars are used in collaboration with drawdown charts.
This non-fluorescent material has to be especially rugged in order to maintain its structure and give reliable readings, as the coatings tested are often corrosive or abrasive. These properties include opacity, spreading rate, penetration, and flow & leveling behavior. ( June 2013)ĭrawdown charts are rectangular pieces of non-fluorescent paper which are used to test a variety of coating properties. Please introduce links to this page from related articles try the Find link tool for suggestions. This article is an orphan, as no other articles link to it.
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