The ground subsidence on the underground pipe often is caused with the reduction of the effective stress and the loss of suction in the base course and then,soil drainage into the pipe.The final formation of the cavit...The ground subsidence on the underground pipe often is caused with the reduction of the effective stress and the loss of suction in the base course and then,soil drainage into the pipe.The final formation of the cavity growth in the ground was observed as the ground subsidence.Authors focused this problem and hence performed model tests with water-inflow and drainage cycle in the model ground.The mechanism of cavity generation in the model ground was observed using an X-ray Computed Tomography(CT)scanner.In those studies,water was supplied into the model grounds from the defected underground pipe model in case of the change of relative density and grain size distribution.As results,it was observed that the loosening area was generated from the defected part with water-inflow and some of the soil particles in the ground were drained into the underground pipe through the defected part.And afterward,the cavity was generated just above the defected part of the model pipe in the ground.Based on this observation,it might be said that the bulk density of soil around the defected pipe played one of key factor to generate the cavity in the ground.Moreover,the dimension of the defected part should be related to the magnification of the ground subsidence,in particular,crack width on a sewerage pipe and particle size would be the quantitative factor to evaluate the magnification of the ground subsidence.In this paper,it was concluded that the low relative density of soil would become the critical factor to cause the fatal failure of model ground if the maximum grain size was close to the dimension of crack width of defective part.The fatal collapse of the ground with high relative density more than 80%would be avoided in a few cycles of water inflow and soil drainage.展开更多
A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e.,incineration residues) are commonly disposed as landfill.Meanwhile,reclamation of landfill sites to create a new land space after...A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e.,incineration residues) are commonly disposed as landfill.Meanwhile,reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries.The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction.Indeed,physical and mechanical properties of these new materials should be initially examined at the micro scale,which is the primary fundamental for construction at larger scale.This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading.Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect.Nine types of cement solidified incineration residues in term of different curing period (i.e.,7,14,28 days) and coal fly ash addition content (i.e.,0%,9%,18%) were scanned before and after unconfined compression tests.It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content.Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials.Then,it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength.展开更多
文摘The ground subsidence on the underground pipe often is caused with the reduction of the effective stress and the loss of suction in the base course and then,soil drainage into the pipe.The final formation of the cavity growth in the ground was observed as the ground subsidence.Authors focused this problem and hence performed model tests with water-inflow and drainage cycle in the model ground.The mechanism of cavity generation in the model ground was observed using an X-ray Computed Tomography(CT)scanner.In those studies,water was supplied into the model grounds from the defected underground pipe model in case of the change of relative density and grain size distribution.As results,it was observed that the loosening area was generated from the defected part with water-inflow and some of the soil particles in the ground were drained into the underground pipe through the defected part.And afterward,the cavity was generated just above the defected part of the model pipe in the ground.Based on this observation,it might be said that the bulk density of soil around the defected pipe played one of key factor to generate the cavity in the ground.Moreover,the dimension of the defected part should be related to the magnification of the ground subsidence,in particular,crack width on a sewerage pipe and particle size would be the quantitative factor to evaluate the magnification of the ground subsidence.In this paper,it was concluded that the low relative density of soil would become the critical factor to cause the fatal failure of model ground if the maximum grain size was close to the dimension of crack width of defective part.The fatal collapse of the ground with high relative density more than 80%would be avoided in a few cycles of water inflow and soil drainage.
文摘A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e.,incineration residues) are commonly disposed as landfill.Meanwhile,reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries.The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction.Indeed,physical and mechanical properties of these new materials should be initially examined at the micro scale,which is the primary fundamental for construction at larger scale.This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading.Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect.Nine types of cement solidified incineration residues in term of different curing period (i.e.,7,14,28 days) and coal fly ash addition content (i.e.,0%,9%,18%) were scanned before and after unconfined compression tests.It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content.Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials.Then,it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength.
