Most of the bottom ash generated from the coal burning power plants in Taiwan was often
hydraulically dumped to the nearby coal ash ponds located along the coastline. But the hydraulic
deposited coal ash is loose and prone to liquefaction during earthquake, especially when it was
dumped below the mean sea level (i.e., underwater dumping). Recently, coal ash ponds have been
considered to be the site for future expansion of the power plants. So the liquefaction problem of
the coal ash pond needs to be seriously dealt with. To avoid liquefaction in the coal ash pond, it is
proposed to add cement in the process of hydraulic filling and make it ready for construction as
soon as the filling process has completed. However, if the hydraulic filling is carried out
underwater, there is a segregation problem of cement and coal ash particles. So, a layered cementash
formation inside the coal ash pond is formed. In general, cement and fine particles of coal ash
suspended at the upper layer; the larger size particles of coal ash with trace of cement content
settled down at the bottom. A 3D finite element model (OpenSeesPL) is adopted here to assess the
effects of this cement treated layer formation on reducing liquefaction potential of the coal ash
pond under earthquake shaking.
From the subsoil condition of the site, the coal ash which was deposited below mean sea level
(GL -7.0 to -13.5m) is loose and highly liquefiable under earthquake. If cement is added during
hydraulic filling process, a cement - ash formation will be formed and its liquefaction resistance
will be analyzed here. It can be seen that by increasing the thickness of cement-coal ash formation,
the maximum displacements at the ground surface and the interface between cemented and not
cemented ash layers are decreased. Besides, there is no liquefaction occurring in the cemented coal
ash layer. However, the time to reach initial liquefaction in the untreated coal ash layer is not
affected by changing the thickness of cemented ash layer. In comparison, the time to reach total
liquefaction depends on its location (at the upper part or lower part of the liquefiable soil) or the
thickness of cemented ash layer. Finally, forming a cemented layer in the coal ash pond has proven
to be an effective way to restrain the horizontal ground displacement inside the coal ash pond
during earthquake.

Most of the bottom ash generated from the coal burning power plants in Taiwan was often
hydraulically dumped to the nearby coal ash ponds located along the coastline. But the hydraulic
deposited coal ash is loose and prone to liquefaction during earthquake, especially when it was
dumped below the mean sea level (i.e., underwater dumping). Recently, coal ash ponds have been
considered to be the site for future expansion of the power plants. So the liquefaction problem of
the coal ash pond needs to be seriously dealt with. To avoid liquefaction in the coal ash pond, it is
proposed to add cement in the process of hydraulic filling and make it ready for construction as
soon as the filling process has completed. However, if the hydraulic filling is carried out
underwater, there is a segregation problem of cement and coal ash particles. So, a layered cementash
formation inside the coal ash pond is formed. In general, cement and fine particles of coal ash
suspended at the upper layer; the larger size particles of coal ash with trace of cement content
settled down at the bottom. A 3D finite element model (OpenSeesPL) is adopted here to assess the
effects of this cement treated layer formation on reducing liquefaction potential of the coal ash
pond under earthquake shaking.
From the subsoil condition of the site, the coal ash which was deposited below mean sea level
(GL -7.0 to -13.5m) is loose and highly liquefiable under earthquake. If cement is added during
hydraulic filling process, a cement - ash formation will be formed and its liquefaction resistance
will be analyzed here. It can be seen that by increasing the thickness of cement-coal ash formation,
the maximum displacements at the ground surface and the interface between cemented and not
cemented ash layers are decreased. Besides, there is no liquefaction occurring in the cemented coal
ash layer. However, the time to reach initial liquefaction in the untreated coal ash layer is not
affected by changing the thickness of cemented ash layer. In comparison, the time to reach total
liquefaction depends on its location (at the upper part or lower part of the liquefiable soil) or the
thickness of cemented ash layer. Finally, forming a cemented layer in the coal ash pond has proven
to be an effective way to restrain the horizontal ground displacement inside the coal ash pond
during earthquake.

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