Vias Terrestres

1. Make a plot of the volumetric behavior of soils in the axis weight vs. volume and obtain the equation for volumetric contraction limit using this plot.
2. Explain the method to obtain the shrinkage or contraction limit of the soil. Show the mathematical procedure.
3. Draw the plot that explains how to obtain the Contraction Limit of soils. Obtain the equation.

[pic 1]

[pic 2]

1. What is the definition of voids ratio, porosity, degree of saturation, volumetric water content, gravimetric water content, specific weight of solids, dry volumetric weight and natural volumetric weight of the soil. Give the maximum and minimum values that typical soils have for each one of these parameters.

-void ratio, related to porosity :e= void volume/volume of soil (Vv/Vs)  [0-inf]

-porosity: n=void volume/(volume water+ vol. soil)  (Vv/Vm)*100      [0-100%]

-degree of saturation: (water volume/void volume)*100  (Vw/Vv)*100   [0-100%]

-volumetric water content: volume of water/(volume water+ vol. soil)  (Vw/Vm) [0-1]

-gravimetric water content: (weight water/ weight water+soil)

-Specific weight of solids: [ɣs]=ws/vs      [2-2.8]

-Dry specific weight: ɣd=ɣm/1+w  

-specific weight of sample: ɣm=Wm/Vm

-ɣw=spec. weight water =1

-Specific gravity= Ss=Ws/Vs*ɣw

-specific submerged weight: ɣ’m=ɣm-ɣw

1. Which are the main agents generators of soils? And what is the end product of each one of them?

1.Glaciers- Glaciasl deposits

2.Wind –Wind Deposits

               3.Rivers –Fluvial Deposits

 4.Seas- Marine deposits

5.Gravity – Piedmont or gravity deposits

1. Name the different types of transported soils and give a qualitative measure to each one of them in relation to its strength, compressibility and heterogeneity using the adjectives low, medium, large and very large.

Glaciasl deposits

Gravity deposits

Alluvial deposits

Fluvial Deposits

Lacustrine deposites

Wind deposits

Marine deposits

1. What is the essential reason for the difference in behavior of natural clays and other soil types such as silts and sands?

-Clay minerals are very electrochemically active, they can attract water molecules and ions. Clays have a negative charge because of this soil can hold on to positively charged cations.

1. Why does the presence of water in a soil have so much greater effect on clays than on sand or gravel materials?

-Because some types of clay are unstable in presence of water and susceptible to large volume changes, this because they are very electrochemically active and can attract water and iones.

1. Comment on the difference between the shape and size of clay particles compared to other soil types such as silts and sands.

Majority

1. Stokes' Law applies to determine the size distribution of fine soils, although considered in their law:

(   ) that grains have angular and rounded shapes.

(   X) that particles have spherical shapes.

(   ) the true shape of the grains.

(   ) that the grains have laminar shape.

8.  The Stokes' Law does not apply to larger grains of 0.2 mm because:

(   ) the equipment of field and laboratory do not permit it.

(   ) the particles generate turbulence during the sedimentation process and affect significantly the sedimentation law.

(   ) the experiment is too fast.

(  X ) the particles are affected by the Brownian movement and is not possible their sedimentation. 

1. What happens if the height of fall of the Casagrande cup increases from 1 to 1.1 cm?, explain graphically.

 The cup is repeatedly dropped 10 mm onto a hard rubber base at a rate of 120 blows per minute, during which the groove closes up gradually as a result of the impact. The number of blows for the groove to close is recorded. The moisture content at which it takes 25 drops of the cup to cause the groove to close over a distance of 13.5 millimetres (0.53 in) is defined as the liquid limit. This could alter

1. Write the hypothesis made for the use of the hydrometer for soils.

A hydrometer analysis is the process by which fine-grained soils, silts and clays, are graded. Hydrometer analysis is performed if the grain sizes are too small for sieve analysis. The basis for this test is Stoke's Law for falling spheres in a viscous fluid in which the terminal velocity of fall depends on the grain diameter and the densities of the grain in suspension and of the fluid. The grain diameter thus can be calculated from a knowledge of the distance and time of fall. The hydrometer also determines the specific gravity (ordensity) of the suspension, and this enables the percentage of particles of a certain equivalent particle diameter to be calculated.

...