Case Study As part of an Operational Improvements Capital Construction project, a section of Hwy 17 in Northwest Region is being realigned. The realigned highway is approximately 300 m long. The horizontal alignment offset varies between the outer limits where the existing connects with the new highway upto 20 metres. The profile grade is such that upto 10 metres of fill height is required. The subsurface conditions at the site consist of a deposit of a deposit of peat approximately 2-3 metres in thickness underlain by a varved clay of approximately 10 metres thickness. The varved clay is underlain by a deposit of sand and gravel of approximately 10 metres thickness which in turn is underlain by granite gneiss bedrock. The varved clay has a shear strength profile as follows: 0-1 metres 50 kpa 1-7 metres 25 kpa 7-10 metres 40 kpa The compressibility charactertistics of the varved clay are such that the preconsolidation pressure in excess of the overburden pressure is approximately 50 kPa with an initial void ratio (eo)of approximately 2.0 and a compressibility index (Cc) of 0.5. The groundwater table in the peat and varved clay is at the ground surface whereas the sand and gravel is under an artesian condition of approximately 3 metres in excess of the ground surface. The presentation & Discussion shall the address the following: Approach Embankment Design Stability Analyses Settlement Calculations Alternatives with a recommended preferred option Construction Considerations
Case Study
As part of an Operational Improvements Capital Construction project, a section of Hwy 17 in Northwest Region is being realigned. The realigned highway is approximately 300 m long. The horizontal alignment offset varies between the outer limits where the existing connects with the new highway upto 20 metres.
The profile grade is such that upto 10 metres of fill height is required.
The subsurface conditions at the site consist of a deposit of a deposit of peat approximately 2-3 metres in thickness underlain by a varved clay of approximately 10 metres thickness. The varved clay is underlain by a deposit of sand and gravel of approximately 10 metres thickness which in turn is underlain by granite gneiss bedrock.
The varved clay has a shear strength profile as follows:
0-1 metres 50 kpa
1-7 metres 25 kpa
7-10 metres 40 kpa
The compressibility charactertistics of the varved clay are such that the preconsolidation pressure in excess of the overburden pressure is approximately 50 kPa with an initial void ratio (eo)of approximately 2.0 and a compressibility index (Cc) of 0.5.
The groundwater table in the peat and varved clay is at the ground surface whereas the sand and gravel is under an artesian condition of approximately 3 metres in excess of the ground surface.
The presentation & Discussion shall the address the following:
- Approach Embankment Design
- Stability Analyses
- Settlement Calculations
- Alternatives with a recommended preferred option
- Construction Considerations
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