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Uplift resistance of a buried pipeline in silty soil on slopes
Published in Andrew McNamara, Sam Divall, Richard Goodey, Neil Taylor, Sarah Stallebrass, Jignasha Panchal, Physical Modelling in Geotechnics, 2018
The model pipe was installed in a trench dug into the model slope at various depths. The model pipeline was placed parallel to the fall line of the hill. The centrifuge was accelerated such that the model hill and pipe experienced as stress-state of N = 90 g at midslope. The 1-D actuator and pipe were made to displace vertically at a rate of 0.5 mm/min at model scale, corresponding to 4 m per day at prototype scale, which is extremely rapid in the scale of landslide movement rates (Cruden & Varnes, 1996). The pipe was displaced vertically to approximately 3 to 5 pipe diameters, which is well beyond previous studies. The pipe and soil were placed against a vertical glass window such that the pipe and soil displacement could be captured with a camera in cross-section. While not described here, the soil texture was tracked using direct image correlation (DIC), utilizing the open-source image processing package Geo-PIV-RG (Stanier et al. 2016).
The use of geochemical methods in the investigation of hazardous waste sites in covered karst terrain
Published in Barry F. Beck, Felicity M. Pearson, Karst Geohazards, 2018
Tim Glover, Joe Daniel, Andrew Lonergan
The Dougherty Karst Plain is bounded on the northwest by the Fall Line Hills District and on the southeast by the Curry Ridge solution escarpment and the Tifton Uplands District. The regional geology is characterized by alternating units of sand, clay, sandstone, dolostone, and limestone that gently dip and progressively thicken to the southeast. These sediments extend to a depth of at least 5000 feet below land surface.
Balanced carving turns in alpine skiing
Published in Sports Biomechanics, 2023
On slopes of moderate gradient, the saturation speed of fall-line gliding is close to , which is significantly above . However, the speed of carving runs saturates near , mostly because of the frictional energy losses. The closeness to the speed limit makes the carving turns quite extreme. Their shape deviates from the rounded shape of the letter C and reminds the letter J instead, with the local turn curvature significantly increasing on the approach to the fall line. As the curvature increases, the centrifugal force and hence the total g-force experienced by the skier grow. In order to stay in balance, they have to adopt large inclination to the slope. The significantly increased effective gravity leads to high normal reaction from the snow and hence significantly increased friction, which is the reason why the speed stays well below .
Comparing 1-D sediment transport modeling with field observations: Simkins Dam removal case study
Published in International Journal of River Basin Management, 2019
Yantao Cui, Mathias J. Collins, Mary Andrews, Graham C. Boardman, John K. Wooster, Marty Melchior, Serena McClain
The 950 km2 watershed west of Baltimore, Maryland (Figure 1) is mostly in the Piedmont physiographic province (85%), a dissected, gently rolling landscape with maximum basin elevations generally less than 300 m (Smith and Wilcock 2015). The river is primarily gravel-bedded, except the downstream-most 12 km where it becomes sand-bedded. The gravel-sand transition occurs roughly at the contact between the Piedmont and the Atlantic Coastal Plain, a regional physiographic feature called the Fall Line. Upstream of the Fall Line in the study area the river flows through an incised, confined, and comparatively high gradient valley and the bed is close to the igneous bedrock (Costa 1975, MDNRWS 2005). Downstream, the valley is lower gradient and unconfined and the channel is formed in relatively thick, unconsolidated Quaternary sediments (Cleaves et al.1968).