1. Geotechnical Engineering II

2. Overview
The design of foundation requires the consideration of many essential factors with regard to soil data, geology of the site, land use patterns, ground conditions and the type of structure to be built. A detailed understanding of the field situation is also very important apart from theoretical knowledge of the subject. This subject seeks to provide an overview of the essential features of foundation design. The different aspects of foundation engineering ranging from soil exploration to the design of different types of foundation, including the ground improvement measures to be taken for poor soil conditions have been covered in this subject.

3. Unit I: Soil Exploration
Soil Exploration – Need – Methods of soil exploration – Boring and Sampling methods – Field tests – Penetration tests – Plate load test – Pressure meter – Planning of programme and preparation of soil investigation report.

4. Lecture Plan
1stHour:
Introduction to Foundation Engineering & soil exploration
2ndHour:
Objectives of soil exploration
3rdHour:
Planning, location and depth of exploration
4thHour:
Methods of exploration : Open excavations
5thHour:
Methods of drilling : Auger, washing, percussion
6thHour:
Rotary drilling, core drilling, sampling tools design

5. 7thHour:
Open tube sampler, undisturbed sampling
8thHour:
Split spoon sampler, standard penetration test, piston sampler
9thHour:
Different types of samples, shifting samples
10thHour:
Vane shear test, penetration tests, plate load test
11thHour:
Pressure meter, Preparation of soil Investigation report
12thHour:
Geophysical methods

6. Objectives
The first Unit is on Soil Exploration and Geophysical Investigation which includes:
Planning for subsurface exploration
Methods of exploration
Geophysical exploration
An overview on soil sampling and samplers
In-situ and common soil tests
Finally the writing of a soil investigation report.

7. Objectives of Site Investigation
To access the general suitability of the site
To achieve safe and economical design of foundations and temporary works.
To know the nature of each stratum and engineering properties of the soil and rock, which may affect the design and mode of construction of proposed structure and foundation.

8. Objectives of Site Investigation
To foresee and provide against difficulties that may arise during construction due to ground and other local conditions.
To find out the sources of construction material and selection of sites for disposal of water or surplus material.
To investigate the occurrence or causes of all natural and man made changes in conditions and the results arising from such changes.

9. Objectives of Site Investigation
To ensure the safety of surrounding existing structures.
To design for the failed structures or remedial measures for the structures deemed to be unsafe.
To locate the ground water level and possible corrosive effect of soil and water on foundation material.

10. Planning For Subsurface Exploration
The planning of the site exploration program involves location and depth of borings, test pits or other methods to be used, and methods of sampling and tests to be carried out. The purpose of the exploration program is to determine, within practical limits, the stratification and engineering properties of the soils underlying the site.

11. The investigation is therefore performed in the following phases:
Fact finding and geological survey
Assemble all information on dimensions, column spacing, type and use of structure, basement requirements, and any special architectural considerations of the proposed building.
Reconnaissance  
This may be in the form of a field trip to the site which can reveal information on the type and behavior of adjacent sites and structures such as cracks, noticeable sags, and possibly sticking doors and windows.      

12. Preliminary exploration:
 Preliminary exploration: In this phase a few borings are made or a test pit is opened to establish in a general manner the stratification, types of soil to be expected, and possibly the location of the groundwater table.
Detailed exploration Where the preliminary site investigation has established the feasibility of the project, a more detailed exploration program is undertaken. The preliminary borings and data are used as a basis for locating additional borings, which should be confirmatory in nature, and determining the additional samples required.

13. Methods of Site Exploration
The various types of site investigation are:
Open excavation
Boring
Subsurface Sounding
Geophysical Methods
These available methods of exploration can be broadly classified into two categories: Direct methods Indirect methods  

14. Methods of Site Exploration
Direct Methods: Pits, Trenches, Drifts & Shafts
Semi-Direct Methods: Borings
Indirect Methods: Geophysical Methods

15. Borings Auger Boring Wash Boring Rotary Drilling Percussion Drilling
Core Boring

16. Augers

17. Wash Boring

18. Rotary drilling

19. Percussion drilling

20. Types of Soil Samples
Disturbed Samples: Representative samples & Remoulded Samples.
Undisturbed Samples

21. Requirement of Good Sampling Process/Design Features affecting sample disturbance
Area Ratio
Inside Clearance
Outside Clearance
Inside wall friction
Design of Non-return Valve
Method of applying force

22. Type of Samplers Split spoon sampler Scraper Bucket sampler
Shelby tubes and thin walled sampler
Piston sampler
Denison sampler
Handcarved samples

23. Field Tests Standard Penetration Test
Cone penetration tests: Static cone penetration test, Dynamic cone penetration tests
Pressure meter tests
Plate load tests

24. Dynamic cone penetration test set up

25. Menard type Pressuremeter

26. Pressuremeter Field Curve

27. Plate Load Test setup

28. Seismic refraction method

29. Test set up for electrical resistivity method

30. Resistivity Sounding