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vikram.jeet
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PostPosted: Sun Aug 29, 2021 2:21 am    Post subject: Reply with quote

MODULUS OF SUBGRADE REACTION

This parameter is very important for structural designers ,especially working on softwares , as it needs to be input to define the foundation soil as closely spaced springs.
The tributary area around springs is multiplied with Modulus of subgrade K value to input the foundation soil. Inner springs and edge &corner springs have different values depending on tributary areas.
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vikram.jeet
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PostPosted: Mon Aug 30, 2021 4:30 am    Post subject: Reply with quote

SOIL MECHANICS DATA FOR INTEREST OF STR ERS

PARTICLE SIZE

BOULDER >  300MM
COBBLE   150 to 300 MM
GRAVEL  2.0 MM (OR 4.76MM) TO 150MM
SAND      0.060MM(OR 0.076MM) TO 2.0MM (OR 4.76MM)
SILT    0.002MM TO 0.06 MM (OR 0.076MM)
CLAY   <  0.002MM


COURTESY
SOIL MECHANICS BY  T WILLIAM LAMBE & ROBERT V WHITMAN, PROFFESORS OF CKVIL ENGG , MIT with special assistance of H G POULOS , UNIVERSITY OF SYDNEY
JOHN WILLEY & SONS , NEWYORK,BRISBANE, TORONTO, SINGAPORE
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PostPosted: Mon Aug 30, 2021 4:54 am    Post subject: Reply with quote

SOIL DATA FOR INTEREST OF STR ERS

STANDARD PENETRATION TEST( PENETRATION RESISTANCE N, NOS OF BLOWS PER 305 MM)

RELATIVE DENSITY OF SAND
VERY LOOSE  -  N VALUE  0 - 4
LOOSE           -  N VALUE   4 - 10
MEDIUM    -  N VALUE   10 -  30
DENSE      -  N VALUE   30 - 50
VERY DENSE -  N VALUE  >  50


STRENGTH OF CLAY
VERY SOFT  -  UCS < 24 KN/m2   ,  N VALUE < 2
SOFT    UCS  24 - 48 KN/m2    ,  N VALUE  2 - 4
MEDIUM -  UCS 48 - 96 KN/m2 , N VALUE 4 - 8
STIFF   -  UCS 96 - 192 KN/m2  , N VALUE  8 - 15
VERY STIFF  - UCS 192 - 388 KN/m2 ,  N VALUE  15 - 30
HARD   -    UCS > 388 KN/m2  ,  N VALUE  > 30


FROM TERZAGHI & PECK 1948
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PostPosted: Mon Sep 06, 2021 4:36 am    Post subject: Reply with quote

SOIL DATA FOR INTREST OF STR ENGINEERS

FIELD VALUES OF COEFFICIENT OF EARTH PRESSURE AT REST (K0)
LOOSE SAND   -  0.4
DENSE SAND -  0.6
SAND WELL TAMPED - - - 0.8
SOFT CLAYS   - - -  0.6
HARD CLAYS  - - - 0.5

AS PER SOIL MRCHANICS AND FOUNDATION ENGG BY H P OZA
Table 14.1
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PostPosted: Mon Sep 06, 2021 6:00 am    Post subject: Reply with quote

SOIL DATA FOR INTREST OF STR DESIGNERS

EARYH PRESSURE AT REST
Assuming soil as elastic material , a soil element subject to stresses in three directions undergo strains .  V being poisson ratio.
z (vertical) = [fz- V*(fx + fy)]/E - - - -
x (Horz) = [fx  - V* (fy + fz ) ]/E
y ( Horz ) =[ fy - V* ( fx + fz )]/E
Soil element can undergo  strain vertically in z direction under load , but it cannot deform laterally in X and y directions due to infinite extent in these directions. This means x = y =0 and because of symmetry,  lateral stresses fx = fy.
Considering 3rd equation
fy  -  V*( fy + fz ) = 0  since fx =fy

fy/fz =  V / (1 - V)
So lateral Earth Pressure at rest coefficient Ko =  V / (1 - V)

Ko can be known if poisson ratio is known , but since soils are not elastic materials , do not have well defined poisson's ratios.
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PostPosted: Mon Sep 06, 2021 10:44 am    Post subject: Reply with quote

SOIL DATA FOR INTEREST OF STR ENGINEERS

POISSON'S RATIO

By assuming soil to be incompressible in all directions :
z + y + x  =0

The relation emerges as

(1 - 2V)/E  *   ( x+ y + z )  = 0

V = 0.5

This is theoretical maximum value of poisson ratio for any material in incompressible state . FOR COMPRESSIBLE MATERIAL S THE VALUE OF POISSON RATIO IS SLWAYS LESS THAN 0.50  .
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PostPosted: Tue Sep 07, 2021 9:54 am    Post subject: Reply with quote

KARL TERZAGHI (1883 - 1963)

Karl TERZAGHI is father of SOIL MRCHANICS. Born in Prague , Austria on 2nd October.
Studied Mechanical engineering and graduated in 1904 and completed essential year in Army , followed by study in Geology on Civil Engg projects. Received Doctor of Technical Sc degree in 1912 for his work on reinforced Concrete.
Taught and worked for ten yrs in Istanbul , and in 1923 published fundamental differential equation for consolidation processes , 1924 paper on consolidation of clays  and in 1925 a famous book on SOIL MECHANICS.
The Science of Soil Mechanics emerged thereafter , and TERZAGHI devoted his rest of life in its research, teaching and practice.
Ultimate settled in states and worked for MIT  and HARVARD.
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PostPosted: Thu Sep 09, 2021 5:38 am    Post subject: Reply with quote

SOIL DATA FOR INTEREST OF STR ERS

VALUES OF POISSON'S RATIO FOR SOME SOILS & MATERIALS

CLAY
Soft    - - - 0.25 - 0.40
Medium  - - - 0.3 - 0.35
Stiff  - - - - 0.20 - 0.30

SAND
Loose  - - - 0.15 - 0.25
Medium - - - 0.25 - 0.30
Dense  - - - 0.25 - 0.35

STEEL - - -  0.27 - 0.30
RUBBER - - - 0.50
CORK  - - -  ZERO

( Source : Internet)
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PostPosted: Thu Sep 09, 2021 6:53 am    Post subject: Reply with quote

SOIL DATA FOR INTEREST OF STR ERS

YOUNGS MODULUS OF SOIL  Es (in  ton/sqft)

( As per US ARMY CORPS OF ENGINEER PUBLICATION )

CLAYS
Very soft  - - 5  -  50  ton / sqft  
Soft clays - - - 50  -  200
Medium clay  - - -  200 - 500
Stiff clay / silty clay. - - - 500 - 1000
Sandy Clay. - -  - - - 250 - 2000

Clay shale  - - -  1000 - 2000

SANDS
Loose sand  - - - -  100 - 250
Dense sand - - - -  250 - 1000
Dense sand & Gravel - - -  1000 - 2000
Silty sand  - - - 250 - 2000


Values in Tonne/ sqft
For values in Tonne per sqm  , Multiply with 10 roughly .
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PostPosted: Wed Sep 22, 2021 10:00 am    Post subject: Reply with quote

SOIL DATA FOR INTEREST OF STR ERS

POISSON'S RATIO  &  YOUNGS MODULUS OF ROCKS, CONCRETE , STEEL ALUMINIUM

NOTE : VALUES OF YOUNG S MODULUS IN MN/m2 unless specified

CONCRETE :  V= 0.15    :   E = 5000√Fck.   in N/mm2
STEEL          :  0.28 - 0.29.        200 X 1000 MN/m2
ALUMINIUM : 0.34 - 0.36       55.2 - 75.8 1000 MN/m2
ICE              : 0.36                     7.10 1000

GRANITE     :  0.23 - 0.27.       73.1 - 86.2 1000
Limestone  :.  0.27 - 0.30.       86.9 - 107.6 1000
MARBLE   :    0.27 - 0.30.         86.9 - 107.6 1000

MICA SCHIST : 0.15 - 0.20.     79.3 - 101.4 1000

QUARTZITE  :  0.12 - 0.15        82.1 - 96.5 1000
DOLOMITE  :  0.30                    110.3 - 121.3 1000

GNEISS   :    0.15 - 0.20             82.7 - 118.6 1000
SLATE. :.       0.15 - 0.20.            79.3 - 112.4 1000

ROCK SALT : 0.25.                   35.4 1000

COURTESY : BRACE (1966) - ROCKS , LANGE (1956) - STEEL & AL
As PROVIDED IN THE BOOK SOIL MECHANICS BY T WILLIAM LAMBE AND ROBERT WHITMAN
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