Hydrologic performance of bioretention systems is significantly influenced by the media composition and underdrain configuration. This research measured hydrologic performance of column-scale bioretention systems duri...Hydrologic performance of bioretention systems is significantly influenced by the media composition and underdrain configuration. This research measured hydrologic performance of column-scale bioretention systems during a synthetic design storm of 25.9 mm, assuming a system area：catchment area ratio of 5%. The laboratory experiments involved two different engineered media and two different drainage configurations. Results show that the two engineered mediawith different sand aggregates were able to retain about 36% of the inflow volume with tree drainage conlaguratlon. However, the medium with marine sand is better at delaying the occurrence of drainage than the one with pumice sand, denoting the better detention ability of the former. For both engineered media, an underdrain configuration with internal water storage （IWS） zone lowered drainage volume and peak drainage rate as well as delayed the occurrence of drainage and peak drainage rate, as compared to a free drainage configuration. The USEPA SWMM v5.1.11 model was applied for the tree drainage configuration case, and there is a reasonable fit between observed and modeled drainag.e-rates when media-specific characteristics are available. For the IWS drainage configuration case, air entrapment was observed to occur in the engineered medium with manne sand. F^lhng ot an IWS zone is most likely to be influenced by many factors, such as the structure of the bioretention system, medium physical and hydraulic properties, and inflow characteristics. More research is needed on the analysis and modeling of hydrologic process in bioretention with IWS drainage configuration.展开更多
This study involved the construction and explosion of a large-scale(80-meter-long)underdrain and detailed investigations of the damaging impacts of a gas explosion to provide an experimental foundation for similarity ...This study involved the construction and explosion of a large-scale(80-meter-long)underdrain and detailed investigations of the damaging impacts of a gas explosion to provide an experimental foundation for similarity modeling and infrastructural designs.The experiment vividly recreated the scene and explosion damage of the"11.22″explosion accident in Qingdao,China,thus allowing for evaluations of the movements and destruction of the cover plates.The damage mechanism was determined by analyzing the overpressure curves inside and outside the underground canal.It was determined that the cover plates were first lifted by the precursor wave,which induced a maximum overpressure of 0.06 MPa and resulted in explosion venting.The pressure entered the deflagration stage at the end of the explosion.The combustion wave overpressure reached 3.115 MPa close to the initiation point,and had a significant influence on the projectile energy of the cover plates there.Overall,64%of the cover plates were only affected by the precursor wave,while 36%of the cover plates were subjected to both the precursor wave and the combustion wave;these cover plates were severely damaged.The results of this study provide fundamental insights relevant to the prevention and control of underdrain gas explosions.展开更多
文摘Hydrologic performance of bioretention systems is significantly influenced by the media composition and underdrain configuration. This research measured hydrologic performance of column-scale bioretention systems during a synthetic design storm of 25.9 mm, assuming a system area：catchment area ratio of 5%. The laboratory experiments involved two different engineered media and two different drainage configurations. Results show that the two engineered mediawith different sand aggregates were able to retain about 36% of the inflow volume with tree drainage conlaguratlon. However, the medium with marine sand is better at delaying the occurrence of drainage than the one with pumice sand, denoting the better detention ability of the former. For both engineered media, an underdrain configuration with internal water storage （IWS） zone lowered drainage volume and peak drainage rate as well as delayed the occurrence of drainage and peak drainage rate, as compared to a free drainage configuration. The USEPA SWMM v5.1.11 model was applied for the tree drainage configuration case, and there is a reasonable fit between observed and modeled drainag.e-rates when media-specific characteristics are available. For the IWS drainage configuration case, air entrapment was observed to occur in the engineered medium with manne sand. F^lhng ot an IWS zone is most likely to be influenced by many factors, such as the structure of the bioretention system, medium physical and hydraulic properties, and inflow characteristics. More research is needed on the analysis and modeling of hydrologic process in bioretention with IWS drainage configuration.
基金The authors gratefully acknowledge financial support given by the National 135 Key R and D Projects(Grant Nos.2018YFF0301000)as well as from the National Science Foundation of China(Grant Nos.71861167002,51834007).
文摘This study involved the construction and explosion of a large-scale(80-meter-long)underdrain and detailed investigations of the damaging impacts of a gas explosion to provide an experimental foundation for similarity modeling and infrastructural designs.The experiment vividly recreated the scene and explosion damage of the"11.22″explosion accident in Qingdao,China,thus allowing for evaluations of the movements and destruction of the cover plates.The damage mechanism was determined by analyzing the overpressure curves inside and outside the underground canal.It was determined that the cover plates were first lifted by the precursor wave,which induced a maximum overpressure of 0.06 MPa and resulted in explosion venting.The pressure entered the deflagration stage at the end of the explosion.The combustion wave overpressure reached 3.115 MPa close to the initiation point,and had a significant influence on the projectile energy of the cover plates there.Overall,64%of the cover plates were only affected by the precursor wave,while 36%of the cover plates were subjected to both the precursor wave and the combustion wave;these cover plates were severely damaged.The results of this study provide fundamental insights relevant to the prevention and control of underdrain gas explosions.
