In the seismic refraction method, the waves sent along the ground surface is picked by _____

For undisturbed sampling, the penetration of the sampler should be periodic.

The inside clearance of the sampler is ____

What are the methods used for general exploration?

In detailed exploration, the field test is conducted to determine ____

Thick wall samplers have area ratio______

Refusal of standard penetration test occurs when the sampler penetrates ____

The important factor affecting soil cement is________