266 resultados para Rock fall
Resumo:
A laboratory investigation was undertaken to determine the limiting model Reynolds number above which the scour behavior of rock protected structures can be reproduced in hydraulic models scaled according to the Froude criterion. A submerged jet was passed over an initially full scour pocket containing uniform glass spheres and the rate of scour was measured as a function of time. The dimensions of the scour pocket and jet and the particle diameters were varied as needed to maintain strict geometric similarity. For each of two different Froude numbers the Reynolds number was varied over a wide range. The normalized scour rate was found to be practically independent of the Reynolds number, R, (based on the jet velocity and particle diameter) at values of R above about 2.5 x 10^3, and to decrease with Rat smaller values. A grid placed in the jet was found to have a very strong effect on the scour rate. In an attempt to explain the effect of R on the scour behavior, turbulent pressure and velocity fluctuations were measured in air flows and water flows, respectively, over rigid scour pockets having the same geometry as those formed in the scour experiments. The normalized spectra of the fluctuations were found to be nearly independent of R, but the flow pattern was found to be very sensitive to the inlet condition, the jet deflecting upward or downward in a not wholly explainable manner. This indicates that scour behavior can be modeled only if the approach flow is also accurately modeled.
Resumo:
The road paving cost continues to increase and the backlog of projects waiting for funding is growing. Finding a more cost-effective way to use the available money to pave roads will result in more miles of road being paved with the same amount of money. This project is in Cass County on G35 between US 71 and Norway-Center. It consists of a thin layer of asphalt over a base designed to achieve stability while having some permeability. This project was paved in 1996. An asphalt cement concrete pavement was chosen for the project based on cost, convenience, and historic portland cement concrete problems in Cass County. The new pavement gives quicker access time to farms and residences.
Carbonate Rock Pore Size Distribution Determination through Iowa Pore Index Testing, MLR-15-01, 2015
Resumo:
The Iowa Pore Index (IPI) measures the pore system of carbonate (limestone and dolomite) rocks using pressurized water to infiltrate the pore system. This technique provides quantitative results for the primary and capillary (secondary) pores in carbonate rocks. These results are used in conjunction with chemical and mineralogical test results to calculate a quality number, which is used as a predictor of aggregate performance in Portland cement concrete (PCC) leading to the durability classification of the aggregate. This study had two main objectives: to determine the effect different aggregate size has on IPI test results and to establish the precision of IPI test and test apparatus. It was found that smaller aggregate size fractions could be correlated to the standard 1/2”-3/4” size sample. Generally, a particle size decrease was accompanied by a slight decrease in IPI values. The IPI testing also showed fairly good agreement of the secondary pore index number between the 1/2”-3/4”and the 3/8”-1/2” fraction. The #4-3/8” showed a greater difference of the secondary number from the 1/2”-3/4” fraction. The precision of the IPI test was established as a standard deviation (Sr) of 2.85 (Primary) and 0.87 (Secondary) with a repeatability limit (%r) of 8.5% and 14.9% for the primary and secondary values, respectively.
Resumo:
Newsletter produced by the Iowa Department of Education, Community College unit. This report has information about staff, grants, statistical data, requirements and more.
Resumo:
Newsletter produced by the Iowa Department of Education, Community College unit. This report has information about staff, grants, statistical data, requirements and more.
Resumo:
The Iowa Department of Education collects enrollment information from all 15 community colleges on the tenth business day of the fall semester. This report summarizes several key aspects of community college enrollment from fall 2012.
Resumo:
Newsletter produced by the Iowa Department of Education, Community College unit. This report has information about staff, grants, statistical data, requirements and more.
Resumo:
The Iowa Department of Education collects enrollment information from all 15 community colleges on the tenth business day of the fall semester. This report summarizes several key aspects of community college enrollment from fall 2012.
Resumo:
CIRAS is to enhance the performance of Iowa industry, and associated entities, through education and technology-based services. This newsletter holds information regarding these services.
Resumo:
A resident within one of the counties in your region has expressed some concern regarding potential adverse health effects from dust and material that may be found within foundry slag that has been used as a replacement for road rock. This consultation includes a comparison of nuisance issues from dust generated from a road constructed of foundry slag and dust generated from a road constructed from typical road rock. This consultation also includes a discussion of the potential health effects of exposure of heavy metals from incidental ingestion of foundry slag.
Resumo:
The Iowa Militiaman is an unofficial publication authorized under the provisions of AR 360-81. It is published by the 135th Mobile Public Affairs Detachment, Camp Dodge, Johnston, Iowa 50131, and is printed four times annually. The news and opinions expressed in this publication are not necessarily those of the Adjutant General of Iowa, or the Department of the Army.
Resumo:
Iowa Department of Veterans Affairs Newsletter
Resumo:
Iowa Department of Veterans Affairs Newsletter
Resumo:
Iowa Department of Veterans Affairs Newsletter
Resumo:
Iowa Department of Veterans Affairs Newsletter
