Highway engineering A highway (20 Km) long traverses a ground of flat terrain between station (7+500) km and station (27+500) km with the following characteristics: for the first (10 Km) composed of (7 m) deep soft, saturated soil whose liquid limit is 43%, plastic limit is 23% and possesses (85%) of particles smaller than 75 microns, the remaining (10 Km) are sandy soil on the top (3.0 m) with gravelly sand underneath whose liquid limit is 15%, plastic limit is 5% and possesses 30% of particles smaller than 75 microns: a) What measures would you take to construct the embankment, if the road between station (7+500) km and station (27+500) km needed as soon as possible? b) Describe the material and check the suitability of it as a subgrade material.
a) To construct the embankment for the road section between station (7+500) km and station (27+500) km as quickly as possible, you would need to consider the following measures:
1.Soil Investigation: Perform a detailed soil investigation to understand the properties of the soil in both the soft, saturated soil section and the sandy soil section. This should include sampling and laboratory testing to determine soil characteristics
2. Excavation and Removal: Excavate the existing soil in the soft, saturated section to the required depth (7 meters) and remove it. Similarly, excavate the sandy soil section to the required depth (3 meters) and remove it.
3. Fill Material: Bring in suitable fill material to replace the removed soil. For the soft, saturated soil section, you would need to use materials that are suitable for creating embankments in saturated conditions. This might involve using sand, gravel, or other well-draining materials.
4. Compaction: Compact the fill material thoroughly in layers to achieve the desired density. Use compaction equipment such as rollers to ensure proper compaction.
5. Drainage: Install drainage systems if necessary to manage water in the soft soil section, as it is saturated. Proper drainage will prevent future settlement and instability.
6. Quality Control: Continuously monitor and test the construction process to ensure that the embankment is being constructed to the required specifications and standards.
7. Traffic Management: Implement traffic management measures to ensure the safety of workers and road users during construction. This may involve temporary traffic diversions or closures.
8. Fast-Tracking: Consider using construction techniques and equipment that can expedite the process, such as using specialized machinery for excavation and compaction.
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