Our engineers designed and tested round and elliptical concrete culverts following the ASCE Standard Practice for Direct Design of Buried Precast Concrete Pipe Using Standard Installations (SIDD). The new design concept brings a direct structural design to precast culverts by simulating the installation with soil zones of different stiffness and the use of finite element analysis to determine the distribution of soil loads and support stresses on the concrete section.
A field test program was conducted to determine soil stiffness and stress distribution for construction conditions of a typical Minnesota highway construction project. Thirty sections of pipe were installed, instrumented and loaded to normal and overload conditions. Pipe deformation and soil stresses were recorded, and the pipe was unloaded, removed, D-load tested and examined.
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Our firm assisted with the development of a rapid method for measuring in-situ soil modulus. The project was an initiative under the Clinton administration’s Technology Reinvestment Project, and developed the Humboldt GeoGauge. The GeoGauge measures in-place resilient modulus and structural stiffness. Side-by-side test measurements show the GeoGauge continues to provide measurements of high accuracy and repeatability.







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Intelligent Compaction (IC) is a technique in the United States construction market that uses an instrumented compactor to control soil or asphalt compaction in real time. This technology provides one of the first opportunities to apply process control to civil construction and potentially provides substantial quality and cost benefits. Potential benefits include: improved quality, reduced compaction costs, both short- and long-term, reduced life cycle cost, greater compaction uniformity increases the useable life of the pavement system.
CNA Engineers determined the viability and competitive benefits of IC, investigated continuous compaction control, assessed the use of the light-weight deflectometer, and developed software and processes for using Geographic Information Systems to process, store and evaluate IC data.

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