Düzce ovası killerinin konsolidasyon özellikleri ve jeolojik evrim ile ilişkisi

Abstract

than overconsolidated clayey layer will take the place of nor mal consolidated clay. Taking into consideration this approach, normal consolidated layers which are observed below the over- consolitated layers were overconsolidated due to the dessica- tion and shallow overburden pressure in the past geological time. With additional sedimentation load by means of increasing the overburden pressure (Po), normal consolidated behaviour of clay has been developed. -112-The clay appers to be soft to medium stiff in spite of its overconsolidation. These properties are due to the low overbur den pressures. If upper clay layers were normaly consolidated Pc values could be similar to Po values, whereas Pc values are higher than Po values, this means that, overconsolidation in this layer has been developed due to the dessication and oxidation. Pc values become equal to Po values with depth. Due to this reason, clay layers have been found in normaly consolidated limits. The most considerable cause of this event is tectonic evolution of the Düzce basin which is still active. The most evident properties of these basins are that the centre of the sedimentation basin moves toward the active fault side of the plain. At the Düzce plain, sedimentation basin is the precently Efteni lake. This means, that in the middle of the plain where the motorway crosses has been rised relatively respect to southern side. The proving factors for the rising of the northern side of the plain is as follows; 1) Inclinations are towards south 2) old Uğursuyu river bed did flow towards north while, it has changed the river bed in the direction of Efteni lake, and 3)Küçük Melen river has dissected its bed out in the Düzce basin deposit and than discharging to Efteni lake. The pore water pressure disappered where the basin rised. Because of this reason dessication has been accelarated at the upper layer. At the Düzce plain which was sedimented in swampy conditions, atmospheric factors such as dessication, oxidation and chan ges in ground water table are the main causes of the overcon solidation properties at the upper clay layer. Due to no additional sedimantation (Po) on this layer at the present time, this layer will remain as overconsolidated and the values of overconsolidation will increase in the future. If addi tional sedimantations will be loaded on this layer, overburden pressure (Po) will reach preconsolidation pressure (Pc) and -111-than overconsolidated clayey layer will take the place of nor mal consolidated clay. Taking into consideration this approach, normal consolidated layers which are observed below the over- consolitated layers were overconsolidated due to the dessica- tion and shallow overburden pressure in the past geological time. With additional sedimentation load by means of increasing the overburden pressure (Po), normal consolidated behaviour of clay has been developed. -112-

The clay appers to be soft to medium stiff in spite of its overconsolidation. These properties are due to the low overbur den pressures. If upper clay layers were normaly consolidated Pc values could be similar to Po values, whereas Pc values are higher than Po values, this means that, overconsolidation in this layer has been developed due to the dessication and oxidation. Pc values become equal to Po values with depth. Due to this reason, clay layers have been found in normaly consolidated limits. The most considerable cause of this event is tectonic evolution of the Düzce basin which is still active. The most evident properties of these basins are that the centre of the sedimentation basin moves toward the active fault side of the plain. At the Düzce plain, sedimentation basin is the precently Efteni lake. This means, that in the middle of the plain where the motorway crosses has been rised relatively respect to southern side. The proving factors for the rising of the northern side of the plain is as follows; 1) Inclinations are towards south 2) old Uğursuyu river bed did flow towards north while, it has changed the river bed in the direction of Efteni lake, and 3)Küçük Melen river has dissected its bed out in the Düzce basin deposit and than discharging to Efteni lake. The pore water pressure disappered where the basin rised. Because of this reason dessication has been accelarated at the upper layer. At the Düzce plain which was sedimented in swampy conditions, atmospheric factors such as dessication, oxidation and chan ges in ground water table are the main causes of the overcon solidation properties at the upper clay layer. Due to no additional sedimantation (Po) on this layer at the present time, this layer will remain as overconsolidated and the values of overconsolidation will increase in the future. If addi tional sedimantations will be loaded on this layer, overburden pressure (Po) will reach preconsolidation pressure (Pc) and -111-than overconsolidated clayey layer will take the place of nor mal consolidated clay. Taking into consideration this approach, normal consolidated layers which are observed below the over- consolitated layers were overconsolidated due to the dessica- tion and shallow overburden pressure in the past geological time. With additional sedimentation load by means of increasing the overburden pressure (Po), normal consolidated behaviour of clay has been developed. -112-The clay appers to be soft to medium stiff in spite of its overconsolidation. These properties are due to the low overbur den pressures. If upper clay layers were normaly consolidated Pc values could be similar to Po values, whereas Pc values are higher than Po values, this means that, overconsolidation in this layer has been developed due to the dessication and oxidation. Pc values become equal to Po values with depth. Due to this reason, clay layers have been found in normaly consolidated limits. The most considerable cause of this event is tectonic evolution of the Düzce basin which is still active. The most evident properties of these basins are that the centre of the sedimentation basin moves toward the active fault side of the plain. At the Düzce plain, sedimentation basin is the precently Efteni lake. This means, that in the middle of the plain where the motorway crosses has been rised relatively respect to southern side. The proving factors for the rising of the northern side of the plain is as follows; 1) Inclinations are towards south 2) old Uğursuyu river bed did flow towards north while, it has changed the river bed in the direction of Efteni lake, and 3)Küçük Melen river has dissected its bed out in the Düzce basin deposit and than discharging to Efteni lake. The pore water pressure disappered where the basin rised. Because of this reason dessication has been accelarated at the upper layer. At the Düzce plain which was sedimented in swampy conditions, atmospheric factors such as dessication, oxidation and chan ges in ground water table are the main causes of the overcon solidation properties at the upper clay layer. Due to no additional sedimantation (Po) on this layer at the present time, this layer will remain as overconsolidated and the values of overconsolidation will increase in the future. If addi tional sedimantations will be loaded on this layer, overburden pressure (Po) will reach preconsolidation pressure (Pc) and -111-than overconsolidated clayey layer will take the place of nor mal consolidated clay. Taking into consideration this approach, normal consolidated layers which are observed below the over- consolitated layers were overconsolidated due to the dessica- tion and shallow overburden pressure in the past geological time. With additional sedimentation load by means of increasing the overburden pressure (Po), normal consolidated behaviour of clay has been developed. -112-