Its a short presentation on the sub soil exploration.Its just representing the set method of sub soil exploration with its application. For report and abstract you can mail me on darkswagger001@gmail.com

1. Sub-soil Exploration
Swagat Kumar Sahoo
B.Tech -7th
Sem.
Veer Surendra Sai University Of Technology

2. Index
• Introduction
• Purpose of Soil Exploration
• Location, spacing and depth of
exploration
• Scope of SSE for Infrastructure Projects
• Stages of SSE
• SPT Methodology & N value
• Soil data analysis through tests
• Conclusion

3. Introduction
• Subsoil exploration is the process by which
Geological, Geo-technical and other relevant
information are acquired.
• Subsoil exploration gives the information
about the Characteristic of soil, strata of soil,
Bearing capacity of soil and also the depth of
ground water table.

4. Purpose of Soil Exploration
 To select the type and depth of foundation.To select the type and depth of foundation.
 To determine the bearing capacity.To determine the bearing capacity.
 To determine the maximum and differentialTo determine the maximum and differential
settlement.settlement.
 To predict lateral earth pressure against retainingTo predict lateral earth pressure against retaining
wall.wall.
 To select suitable construction technique andTo select suitable construction technique and
construction material.construction material.
 To investigate safety of existing foundation andTo investigate safety of existing foundation and
suggest the remedial measures.suggest the remedial measures.

5. Scope of SSE for project works
 The scope of the Sub-Soil Exploration was to obtain theThe scope of the Sub-Soil Exploration was to obtain the
strength parameter of soil in each alternative depth bystrength parameter of soil in each alternative depth by
collecting undisturbed soil samples (UDS) andcollecting undisturbed soil samples (UDS) and
conducting the Standard Penetration Test (SPT) at anconducting the Standard Penetration Test (SPT) at an
interval of 1.5m below ground level as per Cl. 3.3.3 ofinterval of 1.5m below ground level as per Cl. 3.3.3 of
IS:2121-1981IS:2121-1981
 The soil parameters like has been carried out in theThe soil parameters like has been carried out in the
laboratory from the UDS samples.laboratory from the UDS samples.
 The ‘N’ value from the Standard penetration test hasThe ‘N’ value from the Standard penetration test has
been carried out in the field. Basing on the field ‘N’been carried out in the field. Basing on the field ‘N’
value the SBC of the soil has been carried out as per IS:value the SBC of the soil has been carried out as per IS:
6403-1997.6403-1997.

6. Planning of soil exploration
It depends upon
• Nature of sub-soil
• Type of structure
• Importance of structure
METHODS OF SOIL EXPLORATION
•1. Open excavation
•2. Borings
•3. Sub surface soundings
•4. Geographical methods

7. 1. OPEN EXCAVATION
A pit, eventually, can be excavated for exploring shallower depths, say
of the order of 2 to 5 m, or so. Such a pit can be easily excavated at the
proposed construction site, if the soil has a bit of cohesion, and the soil
samples can be lifted from such different depths, besides making the
easy visualization and examination of the different strata. Even
undisturbed soil samples can be lifted from such a pit by a process
called chunk sampling.

8. 2. BORING
• Soil samples can be lifted from deeper depths by drilling
bore holes by using mechanical devices called samplers.
• The process consists of
i. Drilling a hole and visually examining the cuttings coming
out from different depths
ii. Lifting the soil samples from different depths by using
mechanical devices called samplers.

9. 3. SUB-SURFACE SOUNDING TESTS
• These tests are carried our to measure the resistance to penetration of a
sampling spoon, a cone or other shaped tools under dynamic or static
loading. These tests are used for exploration of erratic solid profiles for
finding depth to bed rock or stratum and to get approximate indication of
the strength and other properties of soil.

10. Standard Penetration Test(SPT)
• The test uses a thick-walled sample tube, with an outside diameter
of 50 mm and an inside diameter of 35 mm, and a length of around
650 mm. This is driven into the ground at the bottom of a borehole
by blows from a slide hammer with a weight of 63.5 kg (140 lb)
falling through a distance of 750 mm (30 in).
• The sample tube is driven 150 mm into the ground and then the
number of blows needed for the tube to penetrate each 150 mm (6
in) up to a depth of 450 mm (18 in) is recorded.
• The sum of the number of blows required for the second and third
6 in. of penetration is termed the "standard penetration resistance"
or the "N-value".
• In cases where 50 blows are insufficient to advance it through a 150
mm (6 in) interval the penetration after 50 blows is recorded. The
blow count provides an indication of the density of the ground, and
it is used in many empirical geotechnical engineering formulae.

11. .
• The Standard Penetration Tests aims to determine the SPT N value, which
gives an indication of the soil stiffness and can be empirically related to
many engineering properties.
• The test is conducted inside a borehole. A 'split spoon' sampler is attached
to the bottom of a core barrel and lowered into position at the bottom of
the borehole. The sampler is driven into the ground by a drop hammer
weighing 68 kg falling through a height of 76 cm. The number of hammer
blows is counted. The number required to drive the sampler three
successive 150mm increments is recorded.
• The first increment (0-150mm) is not included in the N value as it is
assumed that the top of the test area has been disturbed by the drilling
process. The SPT N is the number of blows required to achieve
penetration from 150-450mm.
• The hammer weight, drop height, spoon diameter, rope diameter etc. are
standard dimensions.
• After the test, the sample remaining inside the split spoon is preserved in
an airtight container for inspection and description

12. Core barrel

13. Split Spoon Sampler

16. Correlation between SPT-N
value, friction angle, and
relative density
Correlation between SPT-N value and friction angle and Relative density (Meyerhoff
1956)
SPT N3
[Blows/0.3 m - 1 ft]
Soi packing
Relative Density
[%]
Friction angle
[°]
< 4 Very loose < 20 < 30
4 -10 Loose 20 - 40 30 - 35
10 - 30 Compact 40 - 60 35 - 40
30 - 50 Dense 60 - 80 40 - 45
> 50 Very Dense > 80 > 45

17. • .

18. SPT procedure

19. Drilling with Mud pump

20. Data Analysis
 Grain size,Grain size,
 Liquid limit,Liquid limit,
 Plastic limit,Plastic limit,
 Specific gravity,Specific gravity,
 DensityDensity

21. Grain size graph
• .

22. Grain Size Analysis
• .

23. Specific gravity of soil
 Specific gravity is the ratio of the weight in air of a given
volume of a material at a standard temperature to the
weight in air of an equal volume of distilled water at the
same stated temperature.

Specific gravity is defined as the ratio of the unit weight of
soil solids to unit weight of water. The Specific Gravity is
needed for various calculations purposes in Soil Mechanics,
e.g. void ratio, density and unit weight.

For Sandy soil, i.e. soils mostly made of quartz, Specific
Gravity can be accurately estimated to be about 2.65,
whereas for silty and clayey soils, it may vary from 2.6 to
2.9.

24. Application of SPT
• Foundation Determination
• Seismic Analysis
• To investigate safety of existing foundation
and suggest the remedial measures.

25. Under water SSE
• SUB-SOIL EXPLORATION UNDER WATER

26. Conclusion
• Sub soil exploration is a simple and most reliable tests. ThisSub soil exploration is a simple and most reliable tests. This
can also be carried out in for the under water structures.can also be carried out in for the under water structures.
• After the soil investigation , relevant soil test are being carriedAfter the soil investigation , relevant soil test are being carried
out . Basing on this test all the infrastructures have beenout . Basing on this test all the infrastructures have been
constructed.constructed.
• Where we found the failure in projects, the improper or noWhere we found the failure in projects, the improper or no
sub soil exploration may be the most important reason.sub soil exploration may be the most important reason.
• Hence, it is highly essential to conduct for any infrastructureHence, it is highly essential to conduct for any infrastructure
project.project.

27. Further Study :
• 10060:1981 Code of Practice for Sub-Surface investigations for Power
house sites
• 4453:1980 Code of Practice for Sub-Surface investigations by pits,
trenches, drafts and shafts
• 6955:1973 Code of Practice for Sub-Surface investigations for earth &
rock fill dams
• 1892:1979 Code of Practice for Sub-Surface investigations of
foundations
• 13216:1999 Geological exploration for reservoir projects.
• 6403:1981 Determination of Bearing capacity of Shallow foundations

28. REFERENCES:
• Presentation of Standard Penetration Test, equipment layout, correlation between
Ch. Baxter, UNiversity of Rhode Island
• Detailed description of Standard Penetration Test and parameters with
figures J David Rogers, Lecture notes, Advanced Engineering Geology &
Geotechnics, Missouri University of Science and Technology
• Standard Penetration Test on Wikipedia
• Standard Test Procedure Manual for SPT Saskatchewan Highways &
Transportation, Canada
• SPT-CPT Correlations Peter K. Robertson, Richard G. Campanella, A.
Wightman. 1983. Journal of Geotechnical Engineering, Vol. 109, No.11.
ASCE. Available by Prof. P. Robertson's website.
• Subsurface Exploration using the Standard Penetration Test and the Cone
Penetrometer Test J.D. Rogers. 2006. The Geological Society of America.
Environmental and Engineering Geoscience, Vol. XIII, No.2, pp. 161-179.
• Engineering and Design: Standard Penetration Test1988. Technical Letter
No. ETL 1110-1-138, (1988). U.S. Army Corps of Engineers, Washington, D.C.