What is the primary difference between disturbed and undisturbed soil samples?

Disturbed samples have their natural structure modified or destroyed, while undisturbed samples preserve the natural structure and properties.

Fill in the blank: The area ratio (Ar) should be less than ______ for stiff formation and less than ______ for soft clays.

20%, 10%

True or False: Auger boring is suitable for depths greater than 25 meters.

False. Auger boring is typically used for shallower depths, generally about 5 meters.

Riddle: I come in various forms, my layers are deep, I hold the secrets of the earth. What am I?

Soil

What method is commonly used to explore shallower depths of soil?

Open excavation

Fill in the blank: The Standard Penetration Test (SPT) is conducted in a clean hole with a diameter of about ______ mm.

55 to 150

True or False: The recovery ratio (Lr) of 1 indicates poor recovery of soil samples.

False. Lr = 1 indicates good recovery.

Which boring method is specifically used to obtain rock cores?

Rotary boring (core drilling)

Fill in the blank: The resistance to penetration in subsurface sounding tests is measured using a ______.

Sampling spoon or cone

What is the main purpose of site exploration in civil engineering?

To provide reliable, specific, and detailed information about soil and groundwater conditions.

Riddle: I measure the resistance of soil, with a cone that has an angle of sixty degrees. What am I?

Cone penetration test

True or False: Electrical resistivity methods measure changes in soil density.

False. They measure changes in mean resistivity or apparent specific resistance of various soils.

What is the function of the non-return valve in soil sampling?

To permit easy and quick escape of water and air when the sample is driven.

Fill in the blank: The method used for making holes in all types of soils except boulders and rocks is called ______ boring.

Wash

Which factor is crucial in determining the sample disturbance during soil sampling?

Design of samplers and methods of sampling.

True or False: The inside clearance of a sampling tube should be greater than the outside clearance.

False. The inside clearance should not be much greater than the outside clearance.

What type of sample consists of a mixture of soil from different strata?

Non-representative sample