SOIL COMPACTION

SUBMITTED TO : DR. RAJIB SARKAR

GROUP MEMBER: 1.JAY PRAKASH TAK (2013UCE1541)

2.JITESH KUMAR (2013UCE1567)

3.HIMANSHU PATEL (2013UCE1595)

4.RAHUL SINGH (2013UCE1556)

WHAT IS COMPACTION

In geotechnical engineering, soil compaction is the process in which a stress applied to a soil causes densification as air is displaced from the pores between the soil grains.

EFFECT OF COMPACTION ON SOIL STRUCTURE

1. THE WATER CONTENT AT WHICH THE SOIL IS COMPACTED PLAYS AN IMPORTANT ROLE IN SOIL STRUCTURE

2. SOIL COMPACTED AT WATER CONTENT LESS THAN OPTIMUM WATER CONTENT HAVE FLOCCULATED STRUCTURE

3. SOILS COMPACTED AT WATER CONTENT MORE THAN OPTIMUM WATER CONTENT HAVE DISPERSED STRUCTURE

Why Soil Compaction ????

1- Increase Soil Strength 2- Reduce Soil Settlement3- Reduce Soil Permeability4- Reduce Frost Damage5- Reduce Erosion Damage

Factor Affecting Soil Compaction

1.SOIL TYPE

2.WATER CONTENT (WC)

3.COMPACTION EFFORT REQUIRED(ENERGY)

LABORATORY TEST FOR SOIL COMPACTION

1.STANDARD PROCTER TEST

2.MODIFIED PROCTER TEST

Results of Laboratory TestsSr. No. Laboratory Test Result

1 Grain Size Distribution 74.69% fine

2 Specific Gravity (G) 2.65

3 Water Content (Natural) (w) 9.29%

4 Liquid Limit (WL) 56.50%5 Plastic Limit (WP) 29.10%6 Plasticity Index (IP or P.I) 27.40%7 Free Swell Index (F.S.I) 30

8 Optimum Moisture Content (O.M.C.) 20.02%

9 Maximum Dry Density (M.D.D.) 1.63 g/cc

10 California Bearing Ratio (C.B.R.) 2.33%

11 Unconfined Compressive Strength (U.C.S.) at OMC 2.69 Kg/cm2

Types of compaction1- Vibration(Vibratory Force Compaction) 2- Impact (Vibratory Force Compaction)3- Kneading (Static Compaction)4- Pressure(Static Compaction)

Soil Compaction in the Field:

1- Rammers

2- Vibratory Plates

3- Smooth Rollers

4- Rubber-Tire

5- Sheep foot Roller

6- Dynamic Compaction

BENEFIT OF COMPACTION

1. Increase Load-bearing Capacity

2. Prevents Soil Settlement (Better Stability)

3. Reduce Water Seepage

4. Reduces Shrinkage

CASE STUDYSOIL BEARING CAPACITY IN BLACK COTTON SOIL

Case Study Site Location Solapur Road, Keshwapur, Hubli

Purpose:• To procure soil samples for assessing the physical

properties, which will help in design and mode of construction of proposed foundation.

• To determine the nature, thickness and variation of soil strata in the region.

SITE INVESTIGATION

THEORY-1. Black cotton soils and other expansive soils have typical characteristics of shrinkage and swelling due to moisture movement through them.

2. During rainy season, moisture penetrates into these soils, due to which they swell.

THEORY CONTI…1.Most of the fine grained clays, including black cotton soils have their grains which are more or less in the form of sheets , and their grains are not round.

2.When moisture enter between the platelets under some hydrostatic pressure, the particles separate out, resulting in increase in the volume. This increase in volume is commonly known as swelling.

3.During summer season, moisture moves out of the soil and consequently, the soil shrinks. Shrinkage cracks are formed on the ground surface

PROPERTIES OF BLACK COTTON SOIL-

1. CLAYEY

2. THEY SWELL AND BECOME STICKY WHEN WET AND SHRINK WHEN DRIED

3. DURING DRY SEASON, THESE SOILS DEVOLOP WIDE CRACKS.

4. RICH IN LIME AND IRON, NITROGEN AND ORGANIC MATTER

METHODS OF INCREASING SOIL BEARING CAPACITY OF BLACK COTTON SOIL

1) Increasing Depth of Foundation: In granular soil the bearing capacity increases with the depth due to the confining weight of overlying materials. 2) Compaction of soil: Due to the compaction of soil the bearing capacity of the soil increases resulting in reduction in resting settlements 3) Drainage of soil:Due to the presence of water in the soil the bearing capacity of the soil is decreased hence by draining out water the void ratio is improved resulting in higher bearing capacity.

4) Grouting:Bore holes in sufficient numbers are driven in the ground and cement grout is forced through these under pressureDue to which the bearing capacity of soil is increased.

5) Chemical Treatment: In this treatment certain chemicals are grouted in the place of cement grout. The chemical used is such that it can solidify and gain early strength.

Safety Analysis for Soil Bearing Capacity Of Black Cotton Soil

1. The foundation should be taken at Ieast 50 cm lower than the depth of moisture movement. This depth should also be much more than depth of tension cracks.

2. Where this soil occurs only in top layer, and where the thickness of this layer does not exceed 1 to 1.5 m, the entire layer of black cotton soil (or other expansive soil) should be removed, and the foundation should be laid on non-shrinkable non- expansive soil.

Conclusion:Scope of the work was to Study the Soil Bearing Capacity and Properties of Black Cotton Soil for Civil Engineering works.

Following conclusions are made on the basis of test results

The property of volumetric changes with the change of atmospheric conditions makes black cotton soil dangerous to be founded buildings.

It swells excessively when wet and shrinks excessively when dry resulting terrible cracks in soil without any warning.

Hence due to the low Bearing Capacity of Black cotton soil which makes it dangerous for construction of high rise buildings. So all the safety and precautionary methods must be followed before construction of the building.