Abstract
This paper shows the results of a field appliance study of the hydraulic well method to prevent embankment piping, which is proposed by the Japanese Matsuyama River National Highway Office. The large-scale embankment experiment and seepage analysis were conducted to examine the hydraulic well. The experimental procedure is focused on the pore water pressure. The water levels of the hydraulic well were compared with pore water pressure data, which were used to look over the seepage variations. Two different types of large-scale experiments were conducted according to the installation points of hydraulic wells. The seepage velocity results by the experiment were almost similar to those of the analyses. Further, the pore water pressure oriented from the water level variations in the hydraulic well showed similar patterns between the experiment and numerical analysis; however, deeper from the surface, the larger pore water pressure of the numerical analysis was calculated compared to the experimental values. In addition, the piping effect according to the water level and location of the hydraulic well was quantitatively examined for an embankment having a piping guide part. As a result of applying the hydraulic well to the point where piping occurred, the hydraulic well with a 1.0 m water level reduced the seepage velocity by up to 86%. This is because the difference in the water level between the riverside and the protected side is reduced, and it resulted in reducing the seepage pressure. As a result of the theoretical and numerical hydraulic gradient analysis according to the change in the water level of the hydraulic well, the hydraulic gradient decreased linearly according to the water level of the hydraulic well. From the results according to the location of the hydraulic well, installation of it at the point where piping occurred was found to be the most effective. A hydraulic well is a good device for preventing the piping of an embankment if it is installed at the piping point and the proper water level of the hydraulic well is applied.
Highlights
The embankment on a river is made of soil as an important structure that prevents water from overflowing into the exclusion area [1]
Athrnoeuwghhysederpauagliec awnealllywsias.s developed to evaluate the seepage pressure, and the piping was analyzed through seepage analysis
C(o1m) pTahreiswonawteirthdPefeernmsaenmenettMhoedthsosduch as hydraulic wells and installing soil bags refer to em(1e)rgTehnecwy attreeratdmefeenntsethmateitshopdrosmsupcthlyaspehryfdorrmaueldic swoetlhlsaat nthdeinesmtabllainnkgmsoeinl tbdagosesrenfeort tcooellmapesregewnhcyentrtehaetmreeinstatnhaatbinsoprrmomalpittylyinpethrfeoremmebdansokmtheanttthdeuerminbgaanflkmooedn.t Bdyoeisnsntoatllcionlglaaphsyedwrahuelinc twheerlleoirs satnacakbinngorsmoiallibtaygisn, tthhee wematbearnpkrmesesnutreduisriwngeaakeflnoeodd.byByreidnustcailnligngthae hdyifdferareunliccewineltlhoerwstaatcekr ilnegveslobiletbwagese,nththeewriavteerrspidreesasnudrethisewleeaakkepnoeindtboyf trheeduemcinbganthkme denift-. fTehreenrecfeoirne,tihteiswpaotsesriblelveetlobpertewveeennt tthhee criovlelarpsisdeeoafntdhetheemlbeaankkpmoeinntt.oTf htheeseemcobnasntrkumcteinotn
Summary
The embankment on a river is made of soil as an important structure that prevents water from overflowing into the exclusion area [1]. Leakage from a river embankment refers to a phenomenon in which seepage water flows out to the inner site through the bode or the foundation of the embankment due to the rise in the water level in the exclusion site At this time, leakage of the embankment causes the failure of the embankment when the seepage line reaches the slope of the embankment and the infiltrate flows out. The Japanese Matsuyama River National Highway Office (2011) [10] proposes a hydraulic well as a countermeasure to prevent the piping of an embankment This method is a technique that prevents piping by constructing a hydraulic well with a radius of 1.2~2.0 m using soil bags, and it reduces the seepage pressure by the water pressure in the hydraulic well. Where icr is the limit hydraulic gradient, γsub is the unit weight of submerged soil (kN/m3), γw is the unit weight of water (kN/m3), Gs is the specific gravity of soil, and e is the void ratio of soil
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