Sub building and structure or for alteration of

Sub ­Surface Survey

 Depending on the type
of project thorough investigations has to be carried out for identification,
location, alignment and depth of various utilities,

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Sub­ Soil Investigations

 Subsoil investigation
shall be done describing the character, nature, load bearing capacity and
settlement capacity of the soil before constructing a new building and
structure or for alteration of the foundation of an existing structure.

Methods of Exploration

Drilling excavations for sampling;

 Groundwater
measurements;

 Soil sampling for
description of the soil and laboratory tests;

 Groundwater
measurements to determine the groundwater table or the pore pressure profile
and their fluctuations.

1.      
Sounding and Penetration Tests

 Subsurface soundings
are used for exploring soil strata of an erratic nature. They are useful to
determine the presence of any soft pockets between drill holes and also to
determine the density index of cohesion less soils and the consistency of
cohesive soils at desired depths.

2.      
Particle Size Classification

 Depending on particle
sizes, main soil types are gravel, sand, silt and clay. However, the larger
gravels can be further classified as cobble and boulder.

3.      
Engineering Classification of Soils

AASHTO and USCS classification of soil test Criteria for
Assigning Group Symbols and Group Names using Laboratory Tests.

4.      
Classification of Dispersive Soil On the Basis
of Pinhole Test

Fails rapidly under 50 mm head. Dispersive soils D1 and D2

 Erode slowly under 50
mm or 180 mm head Intermediate soils ND4 and ND3

 No colloidal erosion less
than 380 mm or 1020 mm head Non?dispersive soils ND2 and ND1.

5.      DETERMINATION OF RELATIVE
DENSITY OF GRANULAR SOILS
SIGNIFICANCE:

The dry unit weight/density of cohesion less soil does not necessarily, by itself, reveal weather soil
is loose or dense. Only when viewed against the possible range of variation, in terms of relative
density the dry density can be related to the compaction effort used to place the soil in a compacted fill
or indicate volume change and stress-strain tendencies of soil when subjected to external

6.      DETERMINATION OF SHEAR STRENGTH
PARAMETERS OF SOIL BY DIRECT
SHEAR TEST

In many engineering
problems such as design of foundation, retaining walls, slab bridges, pipes,
sheet piling, the value of
the angle of internal friction and cohesion of
the soil involved are required
for the design. Direct shear test is used to
predict these parameters quickly.

7.      Standard Penetration Test (SPT) Vane Shear Test

8.      Pressure meter
Test

 

9.      Dutch Cone Penetration Test
(CPT) Dilatometer test

10.  DETERMINATION OF UNDRAINED SHEAR
STRENGTH BY DIGITAL PENETROMETER

Digital penetrometer is
used
for the determination of
undrained
shear
strength
of both undisturbed and remoulded specimen
of saturated cohesive
soil. It can also
be used for the determination of liquid limit i.e.
the moisture content at which a soil changes
from liquid to plastic state.