Most soil mechanics laboratories still prefer the use of rough end platens during triaxial testing despite an awareness that nonuniform stress conditions occur within the soil specimen. This practice may to some extent be due to a lack of awareness of the magnitude of inaccuracies which may result. This paper describes results from unconsolidated undrained triaxial compression and extension tests in which pore pressures were monitored at the specimen base and at midheight using a circumferentially mounted miniature transducer. The rate of imposed displacement was varied by two orders of magnitude. The significance of displacement rate and specimen end condition is illustrated by presentation of resulting stress ratios and stress paths. Base measured pore pressures were found to be up to 50% higher than the midheight values, depending on the testing rate used. The results indicated that currently accepted criteria for the determination of acceptable displacement rates are adequate.
To investigate nutrient leaching from extensive green roofs, green roof platforms were established to investigate the effluent quantity and quality during artificial rainfall. When the influent volume reached three times the empty bed volume, for which the cumulative rainfall was around 300 mm, the effluent TP and COD concentrations of green roof platforms filled with peat soil did not tend to stabilize. For a long-term operation, the substrate depths had little significant influence on TN, TP and COD concentration...
Field sensor quickly, accurately identifies soil issues
Producers sometimes face challenges that go deep into the soil. They need answers to help the soil, on site. A portable field sensor can accurately measure minerals in soils more easily and efficiently than existing methods. And a research team, including a middle school student and her scientist father, can confirm it.
Calcium, like other minerals, is necessary for healthy plant growth. However, an excess of calcium — particularly in the form of...
Abstract: This paper examines the advantages and limitations of CPTu and SCPTu as an exploration method for geotechnical engineering of Presumpscot Formation. Discussion will include typical results of CPTu and SCPTu data for Presumpscot Formation, application and use for settlement prediction, bearing capacity analysis, slope stability evaluation, and seismic design considerations. Intent is to provide an overview of the Use and Application of Piezocone Penetration Testing for the Presumpscot Formation in...
TRA-63 (TRA-605 Warm Waste Line)
Failure of Underground 4-Inch Radioactive Warm Waste Pipe and Leakage
Discovered During Waste Piping Replacement Construction Project
Quick Facts:
Pipe Material: Duriron Pipe
Pipe Diameter: 4 inches
Hole Size: 1/2-in. offset shear with corrosion
Fluid or Gas in Pipe: Warm Waste Water
Contamination Potential: Radionuclides
On October 9, 2001, during excavation of soil for the 30- in. TRA-605 Warm Waste Pipeline Replacement Project, a radiological control technician...
Moisture distribution in vadose zone soil is the most important parameter for land productivity and vegetation status of ecological systems, and is sensitive to temperature variation. In this study, laboratory scale tests were conducted to determine the effect of temperature on variation in moisture distribution in covered and uncovered conditions. The results indicated that soil moisture from 2.65 to 20 cm was positively correlated with temperature and temperature gradient, and the top 2.65 to 5 cm was dramaticall...
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