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Design of Subtitle D and Subtitle C Landfill Containment Systems
Published in Robert E. Landreth, Paul A. Rebers, Municipal Solid Wastes, 2020
Within natural soil drainage systems there must be located a perforated pipe drainage system to collect and transmit the leachate to a down gradient sump. This piping system is usually HDPE pipe, of either smooth wall or profiled wall varieties. The perforations are usually holes for smooth wall and slots for profiled types. The design procedures follow standard pipe methods, i.e., pipe spacing via the mound model, pipe diameter via hydraulics theory, and pipe strength via the Iowa State formula, see Koerner.2
Design of Manifold Distribution Systems
Published in Roger T. Haug, of Compost Engineering, 2018
Flexible, disposable piping is usually constructed of polyethylene (PE) plastic which provides good resistance to the process temperatures and high moisture environment. Rigid plastic piping, which is intended to be reused, is usually constructed of high density polyethylene (HDPE) to increase its impact resistance. HDPE pipe is usually smooth walled and retains some flexibility. Polyvinyl chloride (PVC) plastic is not favored because it has a tendency to become brittle under repeated hot and cold conditions. Williams and North4 evaluated the use of specially constructed, fiberglass reinforced concrete (FRC) block, which is laid on a sub-base to form a continuous manifold system. Both reusable HDPE pipe and the FRC block were projected to have lower life cycle costs compared to disposable PE pipe. Nevertheless, disposable PE pipe remains the industry workhorse at static pile, sludge composting facilities.
Deformation and stress distribution of floating collar of net cage in steady current
Published in Ships and Offshore Structures, 2019
Yun-Peng Zhao, Xiao-Dong Bai, Guo-Hai Dong, Chun-Wei Bi
As the structural support of the whole fish cage, the structures of the floating system are critical bearer structure to assure the feasibility and safety of marine cage aquaculture and its collapse will give rise to the failure of the whole cage. Attributing to its economic benefits and corrosion resistance, the high-density polyethylene (HDPE) floating pipes have been extensively applied in constructing the floating system of fish cage. However, the application of HDPE pipe increases the risk of the failure, ascribing to the relatively low strength of the composite. Therefore, the performance of the floating structure under vigorous environmental condition is in dire need of investigation. Fredriksson et al. (2007) proposed the finite element modelling techniques to determine the structural capabilities of the HDPE net pen. Bai et al. (2014) and Bai, Yuan, et al. (2015) investigated the mechanical behaviour of the reinforced HDPE pipe based on the nonlinear ring theory. Zhang et al. (2015) analysed stress distributions of the composite pipes joints constructions used in marine engineering equipment under external pressure, internal pressure, tension, bending in the deep sea. Nevertheless, the research on the structural performance and capabilities of floating structure systems of fish cage is still not adequate. To gain an insight into the structural performance and stress distribution of the floating system, a numerical model is presented in the current study. The modelling approach is on the basis of the finite element method combined with a hydrodynamic model. Based on the lumped-mass method and the Morison's formula, dynamic simulation of the fish cage is performed and the load on the floating pipes is determined by the hydrodynamic model. The finite element method using the shell element is employed to model the floating pipes. Using an appropriate iterative scheme, the stress distribution and deformations of the floating pipes can be obtained.