Construction survey

Sampling of the road soil profile up to a depth of 1 m to 3 m below the existing ground level is typically done during the construction survey of a road project. The construction survey is conducted after the final location survey, which determines the exact alignment and levels of the road. The purpose of the construction survey is to provide detailed information about the existing ground conditions and to guide the construction process.

Importance of sampling the road soil profile
Sampling the road soil profile is crucial in order to understand the properties and characteristics of the soil beneath the road surface. This information is essential for designing the road foundation and ensuring its stability and durability. By sampling the soil, engineers can determine the soil type, moisture content, compaction characteristics, and other factors that influence the road's performance.

Sampling depth
Sampling is typically done up to a depth of 1 m to 3 m below the existing ground level. This depth allows engineers to gather sufficient information about the soil profile without excessive excavation or disturbance to the surrounding area. Sampling beyond this depth may not be necessary for road construction purposes unless specific conditions require deeper investigation, such as in areas with unstable soil or high water table.

Sampling methods
There are various methods for sampling the road soil profile, including:

1. Auger drilling: This involves using a mechanical auger to extract soil samples at regular intervals along the road alignment. It is a commonly used method for shallow soil sampling.

2. Test pits: Test pits are excavated manually using shovels or excavators to expose the soil profile. Soil samples can then be collected from different depths within the pit.

3. Cone penetration testing (CPT): CPT involves pushing a cone-shaped penetrometer into the ground and measuring the resistance it encounters. This provides valuable information about the soil's strength and consistency.

4. Laboratory testing: After collecting the soil samples, they are typically sent to a laboratory for further analysis. Laboratory tests can provide detailed information about the soil's physical and mechanical properties, such as particle size distribution, shear strength, and permeability.

Conclusion
In summary, sampling the road soil profile up to a depth of 1 m to 3 m below the existing ground level is an important part of the construction survey. This information helps engineers design the road foundation and ensure its stability and longevity. Various sampling methods, such as auger drilling, test pits, and cone penetration testing, are employed to gather soil samples for further analysis in the laboratory.