1. Introduction to Soil Mechanics

2. LABORATORY TESTS AND EQUIVALLENT FIELD EXPERIMENTS
Soil Index (, , e, GS etc.)
Measurement of soil volume and mass
Sieve analysis test
Atterberg test
Compaction : proctor, field compaction
Shear Strength (c, )
Triaxial Test (UU, CU, CD)
Direct Shear
Unconfined Compression Test
CPT, SPT,Vane Shear test,….
Compresibility (Cc, Cv)
Consolidation test
Permeability (k)
Constant Head
Falling Head

3. Three Phases in Soils S : Solid Soil particle
W: Liquid Water (electrolytes) A: Air Air

4. Three Volumetric Ratios
(1) Void ratio e (given in decimal, 0.65)
(2) Porosity n (given in percent 100%, 65%)
(3) Degree of Saturation S (given in percent 100%, 65%)

5. Engineering Applications (e)
Typical values
Engineering applications:
Volume change tendency
Strength
Simple cubic (SC), e = 0.91, Contract
Cubic-tetrahedral (CT), e = 0.65, Dilate
Demonstration of dilatancy 1885 Reynold
Link: the strength of rock joint i
(Lambe and Whitman, 1979)

6. Engineering Implications (e)(Cont.)
Hydraulic conductivity
Which packing (SC or CT) has higher hydraulic conductivity? SC
e = 0.91 CT
e = 0.65
The fluid (water) can flow more easily through the soil with higher hydraulic conductivity

7. Engineering Applications (e)(Cont.)
Filter SC
e = 0.91
The finer particle cannot pass through the void
Clogging CT
e = 0.65
Critical state soil mechanics

8. Engineering Applications (S)
Completely dry soil S = 0 %
Completely saturated soil S = 100%
Unsaturated soil (partially saturated soil) % < S < 100%
Demonstration:
Effects of capillary forces
Engineering implications:
Slope stability
Underground excavation

9. Engineering Applications (S) (Cont.)
80 % of landslides are due to erosion and “loss in suction” in Hong Kong.
The slope stability is significantly affected by the surface water.
(Au, 2001)

10. Density and Unit Weight
Mass is a measure of a body's inertia, or its "quantity of matter". Mass is not changed at different places.
Weight is force, the force of gravity acting on a body. The value is different at various places (Newton's second law F = ma) (Giancoli, 1998)
The unit weight is frequently used than the density is (e.g. in calculating the overburden pressure).

11. Weight Relationships (3) Density of soil (1)Water Content w (100%)
a. Dry density
b. Total, Wet, or Moist density (0%<S<100%, Unsaturated)
c. Saturated density (S=100%, Va =0)
d. Submerged density (Buoyant density)
(1)Water Content w (100%)
For some organic soils w>100%, up to 500 %
For quick clays, w>100%
(2)Density of water (slightly varied with temperatures)
M:Mega
Please tell student to correct the density of water Mg/m3 instead of Mg/cm3

12. Weight Relationships (Cont.)
Submerged unit weight:
Consider the buoyant force acting on the soil solids:

13. Engineering Applications (w)
For fine-grained soils, water plays a critical role to their engineering properties (discussed in the next topic).
For example,
The quick clay usually has a water content w greater than 100 % and a sensitive structure. It will behave like a viscous fluid after it is fully disturbed.
Clay particle
Water
(Mitchell, 1993)

14. Other Relationships
Specific gravity
Proof:

15. Typical Values of Specific Gravity
(Lambe and Whitman, 1979)
(Goodman, 1989)

16. Determination of Atterberg limits

17. CASAGRANDE METHOD (LL)

18. CASAGRANDE METHOD

19. CASAGRANDE METHOD
SINGLE-POINT

20. PLASTIC LIMIT (PL) Plastic behaviour
The test is done by rolling up the soil sample to 3.2mm diameter
Defined as the water content, in percent, at which the soil crumbles, when rolled into threads of 1/8 in (3.2mm) in diameter.

21. SHRINKAGE LIMIT (SL)
Test Standard : ASTM D 427
After drying the soil sample in an oven, and determining the mass and volume of sample before(i) and after (f) drying:

23. Sieve Analysis
Test Standard
ASTM D422, AASHTO T88
The testing should be only carried out once for one sample

24. Curve of Particle Size Distribution

25. SOIL COMPACTION

26. INTRODUCTION
Soil compaction is defined as the method of mechanically increasing the density of soil.  In construction, this is a significant part of the building process.  If performed improperly, settlement of the soil could occur and result in unnecessary maintenance costs or structure failure

27. SOIL COMPACTION PURPOSE Improving the soil quality by:
Increasing the shear strength of soil
Improving the bearing capacity of soil
Reduces the settling of soil
Reduces the soil permeability
To control the relative volume change

28. 4 types of compaction effort on soil :
Vibration
Impact
Pressure

29. SOIL COMPACTION BASIC THEORY
Developed by R.R. Proctor at 1920-an with 4 variables :
Compaction efforts (Compaction Energy)
Soil types
Water content
Dry Unit Weight
LABORATORY COMPACTION TEST
Standard Proctor Test
Modification Proctor Test
Dietert Compaction
Harvard Miniatur Compaction

30. STANDARD PROCTOR TEST The soil is compacted at cylindrical tube
Specification of test and equipments
Hammer weight = 2,5 kg (5,5 lb)
Falling height = 1 ft
Amount of layers = 3
No. of blows/layer = 25
Compaction effort = 595 kJ/m3
Soil type = pass sieve no. 4
The test is carried out several time with different water content
After compacted, the weight, moisture content and unit weight of samples are measured
Test Standard :
AASHTO T 99
ASTM D698

31. MODIFIED PROCTOR TEST The soil is compacted at cylindrical tube
Specification of test and equipments
Hammer weight = 4.5 kg (10 lb)
Falling height = 1.5 ft
Amount of layers = 5
No. of blows/layer = 25, 56
Compaction effort = 2693 kJ/m3
Soil type = pass sieve no. 4
The test is carried out several time with different water content
After compacted, the weight, moisture content and unit weight of samples are measured
Test Standard :
AASHTO T 180
ASTM D1557

32. TEST RESULT

33. FIELD COMPACTION Type of Compaction Equipment : Smooth Wheel Roller :
compaction equipment which supplies 100% coverage under the wheel, with ground contact pressures up to 400 kPa and may be used on all soil types except rocky soils. Mostly use for subgrades and compacting asphalt pavements.

34. FIELD COMPACTION Type of Compaction Equipment : Rubber Tire Roller :
A heavily loaded wagon with several rows of three to six closely spaced tires with tire pressure may be up to about 700 kPa and has about 80% coverage (80% of the total area is covered by tires).
This equipment may be used for both granular and cohesive highway fills.

35. FIELD COMPACTION Type of Compaction Equipment : Sheepsfoot Roller :
This roller has many round or rectangular shaped protrusions or “feet” attached to a steel drum.
The area of these protusions ranges from 30 to 80 cm2.
Area coverage is about 8 – 12% with very high contact pressures ranging from 1400 to 7000 kPa depending on the drum size and whether the drum is filled with water.
The sheepsfoot roller is best suited for cohesive soils.

36. FIELD COMPACTION Type of Compaction Equipment : Grid Roller :
This roller has about 50% coverage and pressures from 1400 to 6200 kPa, ideally suited for compacting rocky soils, gravels and sand. With high towing speed, the material is vibrated, crushed, and impacted.

37. FIELD COMPACTION Type of Compaction Equipment : Baby Roller :
Small type of smooth wheel roller yang, which has pressure ranges from 10 to 30 kPa. The performance base on static weight and vibration effect.

38. FIELD COMPACTION Type of Compaction Equipment: Vibrating Plate :
Compaction equipment, which has plate shape. In Indonesia this equipment sometimes called as “stamper”. Usually used for narrow area and high risk when use large compaction equipment like smooth wheel roller etc.

39. CONDITIONER FACTORS Characteristic of compaction equipment
Weight and size
Operation frequency and frequency range
Soil Characteristic
Initial density
Soil type
Size and shape of soil particle
Moisture Content
Compaction Procedure
No. of passes of the roller
Layer thickness
Frequency of operation of vibrator
Towing speed

40. FIELD COMPACTION CONTROL
Excavate a hole with certain diameter and depth. Determine the mass of excavated material.
Determine the moisture content
Measure the volume of excavated material by:
Ottawa Sand  Sand cone
The balloon method
Pouring water or oil
Compute the total density,  and d,field
Compare d, field with d,max and calculate the relative compaction

41. SPECIFICATION OF COMPACTION
End Product Specification
Method of Specification
Minimum soil sample 100 kg
Need special experience to find out the optimum moisture content in order to get optimum compaction performance