MACE Academy

Maharashtra Academy for Civil Engineers:
Maharashtra Academy for Civil Engineers
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#Imp topics, notes, framed Objectives
#Soil Mechanics specialist
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Imp one liners -

Offcourse GT che taknar adhi😄

Maximum void ratio is 0.91
Minimum void ratio is 0.35

#void ratio & watercontent has no upper limit.
#porosity can lie within 0 to 100% but not zero and not 100%
#degree of saturation can be zero(dry soil), can be 100%(fully saturated soil, or take intermediate value(moist or partialy saturated soil)

Water content can be found out most accurately by oven drying method, and in-situ by Radiation method
If specific gravity is know then it can be found out by pycnometer also.

Core cutter method and sand replacement method are useful in finding in-situ unit weights of soil

Specific gravity can be found out by pycnometer and indirectly by shrinkage limit.
(NOTE-Degree of saturation at shrinkage limit is 1)

For organic soils specific gravity ranges in 1.2-1.4
And for inorganic soils it is,
2.65-2.80

Sedimentation analysis consist of pipette analysis and hydrometer method

There are "3" corrections in hydrometer method.

Well graded soils have a greater compaction property .
Poorly garaded or uniformly graded consist of same grain size hence voids are there.
A special case of poorly graded soil is the one in which particles are either in excess or deficient called as gap graded soils!

If D10=150 micron, it means 10% particles are finer than 150 micron. . .
Note that D10 is called effective particle size.

For well graded soils 1<Cc<3

For well graded gravels Cu>4
For Well Graded sands Cu>6
For poorly graded soils Cu=1

#Trick?????
G for gavaskar, S for sachin
Gavaskar four(चौका) Marto 😅
Sachin six marto😜

In casagrandes test to find liquid limit water content is found out corresponding to 25 no. Of blows

Plasticity index of sands is zero
Toughness index is (plasticity index/flow index). . .. (#MMRDA 2015)

Sensitivity is always greater than unity and is directly proportional to thixotrophy.

Soil activity was explained by skempton.

Out of various unit weights of soils, saturated unit weight is maximum while submerged unit weight is minimum
( #Gemeraly submerged unit weight is only 50% of saturated weight--------- this point is related to bearing capacity---when water table rises to ground surface unit weight of water falls to 50% hence bearing capacity under submergence condition is reduced by 50%)

Plasticity and activity of montmorilonite is maximum.

Bentoninte is purest form of clay which consist of 98% clay

As compared to normal soils expansive soils have
1. More liquid limit
2. Less plastic limit
3.less shrinkage limit
4.more volumetric shrinkage
5. More plasticity index( from pt. 1 & pt 2)

Clay is finer than 0.002 mm and is flacky in shape(#TRANSCO dec 2016)

Silt is finer than 0.075 mm and coarser than 0.002 mm

Boulders are greater than 300mm
Gravel size is greater than 4.75mm and smaller than 80mm

As per IS 1498:1970😍 classification coarse grained soils are classified into 8 groups while fine grained soils are classified into 10 groups
Thus there are total 18 groups

Eg.
GS would be sandy gravel
Gp - poorly graded gravel
GW- well graded gravel etc

Thats vimp about 1st
2 chapters.
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