The objective of the present study is to evaluate the performance of a levee when subjected to flooding and subsequent seepage through centrifuge model tests. For this, six centrifuge model tests were conducted on a 240 mm high levee model at 30g in a 4.5 m radius large beam geotechnical centrifuge available at the Indian Institute of Technology Bombay, India. A custom-developed flooding simulator is employed to induce identical flood rates on the upstream side of the levee models. Further, using (a) geocomposite (GC) and (b) sand-sandwiched geocomposite (SSGC) as internal chimney drain, the suitability of GC material for dissipation of pore-water pressure (PWP) is also studied. The results of the centrifuge tests are presented and discussed in terms of the development of upstream flood function, subsequent PWP development within the levee body, and the surface settlements observed at the levee's crest. Further, the influence of an internal chimney drain, the material used for its construction, and its type and composition on the seepage response of the levee is discussed in detail. The performance GC chimney drain placed within the levee subjected to flooding-induced seepage is compared with a conventional sand chimney drain. It is observed that a GC-based chimney drain with sand cushioning on both sides in the horizontal portion of the chimney drain performs well. Further, digital image analysis of SEM micrographs of exhumed GC after centrifuge tests and the analyzed PWP data during sustained flooding-induced seepage is found to corroborate well.

Centrifuge-based physical modeling is widely adopted for understanding the performance of geostructures, like reinforced slopes, clay liners of municipal solid waste landfills, geogrid-reinforced soil walls, earthen dams, soil nailed slopes, etc. This study aims to highlight the benefits of centrifuge-based physical modeling in order to comprehend the performance of different geostructures both prior to and during failure. Firstly, a discussion is made on scaling considerations along with modeling aspects of various types of phenomena like rainfall, flooding, etc. Further, details of four types of balanced/beam centrifuge equipment used for understanding the behavior of various types of geostructures at high gravity conditions, along with errors due to radial acceleration field, are also presented. In the process, innovative development of cost-effective actuators for simulating: (1) continuous differential settlements of landfill lining systems, (2) seepage of water through a slope, (3) seepage-induced flooding, (4) dynamic compaction, (5) rainfall-induced seepage, and (6) pseudo-static seismic loading along with flooding-induced seepage has been done. Different types of instrumentation units like potentiometers (P), linearly variable differential transformers, pore-water pressure transducers, load cells, accelerometers, strain gauges, etc., along with wireless data acquisition systems were used for monitoring the performance of the models during centrifuge tests. Additionally, the use of particle image velocimetry, digital image analysis, and the digital-cross correlation technique to evaluate the performance of several models evaluated at high gravity is covered. Lastly, it has been sufficiently shown that using digital image analysis/digital image correlation approaches in conjunction with centrifuge-based physical modeling analysis is a useful study tool. Insights gained in understanding the behavior of geostructures in a geotechnical centrifuge, especially subjected to climatic events like rainfall, flooding, and earthquakes, are highly significant and help in designing and constructing geostructures with confidence to engineers.

Cultural and environmental factors can place creeping bentgrass (Agrostis stolonifera) under extreme stress during the summer months. This stress, coupled with the growth adaptation of creeping bentgrass, can result in shallow, poorly rooted stands of turf. To enhance root zone oxygen and rooting of creeping bentgrass, golf courses use methods such as core and solid-tine aerification, and sand topdressing. An additional method of delivering oxygen to the soil could be irrigation with nanobubble-oxygenated water. The properties of nanobubbles (NBs) allow for high gas dissolution rates in water. Irrigating with NB-oxygenated water sources may promote increased rooting of creeping bentgrass putting greens during high-temperature periods and lead to a more resilient playing surface. The objectives of this study include comparing the effects of irrigation with NB-oxygenated water sources with untreated water sources on creeping bentgrass putting green root zone and plant health characteristics using field and controlled environment experiments. Treatments included NB-oxygenated potable water and irrigation pond water, and untreated potable and irrigation pond water. In the field, NB-oxygenated water did not enhance plant health characteristics of creeping bentgrass. In 1 year, NB oxygenated water increased the daily mean partial pressure of soil oxygen from 17.48 kPa to 18.21 kPa but soil oxygen was unaffected in the other 2 years of the trial. Subsurface irrigation with NB-oxygenated water did not affect measured plant health characteristics in the greenhouse. NB-oxygenation of irrigation water remains an excellent means of efficiently oxygenating large volumes of water. However, plant health benefits from NB-oxygenated irrigation water were not observed in this research.