Anúncio
Anúncio

### INDEX PROPERTIES OF SOIL

1. Presented by: Dr. Sajjad Mangi Associate Professor Department of Civil Engineering MUET, SZAB Campus, Khairpur Mirs INDEX PROPERTIES OF SOIL AND THEIR DETERMINATION
2. a) Water content b) Specific gravity c) In-situ density d) Particle size e) Consistency f) Relative Density
3. Specific gravity (G) is defined as: the ratio of the weight of a given volume of soil solids at a given temperature to the weight of an equal volume of distilled water at that temperature.
4. The specific gravity of solids is frequently required for computation of several soil properties such as void ratio, degree of saturation, unit weight of solids, fine soil particle size, etc. Methods used for determination are:- 1. Pycnometer bottle method 2. Density bottle method 3. Measuring flask method 4. Gas jar method
5. 1. Clean and dry the pycnometer. Find its mass with cap as W1. 2. Place about 200 gm of oven dried soil passing through 4.75 mm sieve. 3. Determine mass of pycnometer with dry soil as W2. 4. Add sufficient amount of distilled - water to the soil in the pycnometer. Thoroughly mix it. Determine mass of pycnometer with soil and water as W3. . .
6. 5. Empty the pycnometer, clean it and wipe it dry. 6. Fill the pycnometer with distilled water and find its mass as W4. 7. Now, calculate the specific gravity (G) of soil solids as under : G =[(W2-W1)/{(W4-W1) - (W3-W2)}]
7. A density bottle of 50 ml capacity is used. Bottle is dried and cleaned at temperature of 105 -110 C. Mass of bottle including o stopper is taken. About 5-10g of soil is taken in the bottle and weighted. Distilled water is added to cover sample. The soil is allowed to soak water for about 2 hours. Air entrapped is expelled by applying a vacuum pressure of 55 cm of mercury. The stopper is inserted in bottle and mass is taken . The bottle is emptied, washed and refilled with distilled water. The mass of bottle filled with water is taken. Let W1= mass of empty container W2= mass of container + dry soil W3= mass of container + wet soil W4=mass of bottle filled with water DENSITY BOTTLE METHOD G =[(W2-W1)/{(W4-W1) - (W3-W2)}]
8. A measuring flask of 250 ml capacity, with a graduation marked at that level .It is fitted with an adaptor for connecting it to a vacuum line for removing entrapped air. This method is similar to density bottle method. About 80-100 g of oven drying sample is taken. Advantage- Suitable for fine grained and medium grained soil.
9. Dry density of soil
10. 1. Measure the inside dimensions of the core cutter 2. Determine empty weight of core cutter ( W1) 3. Level the surface, about 300 mm square in area. 3. Place the dolly over the top of the core cutter and press the core cutter into the soil mass using the rammer. 4. Stop the process of pressing when about 15 mm of the dolly remains above the soil surface. 5. Remove the soil surrounding the core cutter and take out the core cutter. 6. Remove the dolly. Trim the top and bottom surface of the core cutter carefully using a straight edge. 7. Weight the core cutter filled with the soil (W2). 8. Remove the core of the soil from the cutter. Determine the water content
11. DETERMINATION OF FIELD DRY DENSITY -
12. Bulk density, Dry density, Where, w is the water content DETERMINATION OF FIELD DRY DENSITY - M1 M2
13. Determination of ◦ Mass density of sand ◦ Volume of excavated hole ◦ Mass density of soil
14. Mass density of sand
15. Mass density of sand Where, M initial mass of cylinder with sand 1 M mass of sand in cone only 2 M3 mass of cylinder after pouring sand into the cone and the container V volume of the container c
16. Volume of the hole Where, M initial mass of cylinder with sand 1 M mass of sand in cone only 2 M 4 mass of cylinder after pouring sand into the hole ρ mass density of sand s
17. Bulk density, Dry density, Where, w is the water content
18. Particle size analysis is a method of separation of soils into different fractions based on particle size. Particle analysis is done in 2 stages:- 1. Sieve Analysis 2. Sedimentation Analysis The first analysis is meant for coarse grained soil (particle size > 75 micron). Whereas sedimentation analysis is for fine grained soils ( particle size < 75 micron). Particle size smaller than 0.2 micron can be determined by an electron microscope or by X-ray technique.
19. PROCEDURE a) The test sample is dried to a constant weight at a temperature of 110 + 5 C and weighed. o b) The sample is sieved by using a set of BS/ASTM Sieves. c) On completion of sieving, the material on each sieve is weighed. d) Cumulative weight passing through each sieve is calculated as a percentage of the total sample weight. e) Fineness modulus is obtained by adding cumulative percentage of aggregates retained on each sieve and dividing the sum by 100.
20. Particle size, D (mm) Percentage finer, N % 100 90 80 70 60 50 40 30 20 10 0 D10 D30 D60 D – Effective size 10 Uniformity coefficient, Coefficient of curvature,
21. Consistency of soil
22. The consistency of a fine grained soil is the physical state in which it exists. The water content at which the soil changes from one state to other are known as Consistency limits or ATTERBERG limits. At the same water content one soil may be relatively soft, whereas another soil may be hard. Thus consistency limits are very important properties of fine grained soil.
23. 34 Purpose: This is performed to determine the plastic and liquid limits of a fine grained soil. Atterberg limits are based on the moisture content of the soil. The plastic limit: is the moisture content that defines where the soil changes from a semi-solid to a plastic (flexible) state. The liquid limit: is the moisture content that defines where the soil changes from a plastic to a viscous fluid state.
24. 1) The liquid limit device is adjusted to have a free fall of cup of 1cm this is done with the help of adjusting screw provided near the cup hinge. 2) Take 100gm of soil sample after passing from 425µ ASTM sieve. 3) Add 15% water in soil by weight of soil. 4) Mix it thoroughly to make uniform paste. 5) Put wet soil in cup and leveled it at lowest spot and squeezed down with spatula to have a uniform space. 6) Then with the help of casegrande’s tool , divided into two parts by grooving up to bottom surface of cup. 7) Rotate handle at the rate of 2 no. per second and cup will start process of up and down. 8) Count the rotation of handle until the bottom surface of groove is connected . 9) Then add water as 3% of soil and mix thoroughly and repeat process. 10) The process of adding water is contained until connecting of groove is completely in 25 blows. 11) Then get the result of Liquid limit.
25.  The minimum water content at which a soil will just begin to crumble when it is rolled into a thread of approximately 3 mm in diameter. When point is reached where thread is cracking and cannot be re-rolled to 3 mm diameter, collect at least 6 grams and measure water content. The test is repeated taking a fresh sample each time. Plastic limit is taken as an average of three values.
26. Plasticity Index is the numerical difference between the Liquid Limit (%) and the Plastic Limit (%) Plasticity Index = Liquid Limit - Plastic Limit TYPE LIQUID LIMIT Low plasticity < 35% Intermediate plasticity 35 - 50% High plasticity 50 - 70% Very high plasticity 70 - 90% Extremely high plasticity > 90%
27. The relative density is generally used to indicate the in situ (on site) denseness or looseness of soil. It is defined by:-
28. The relative density of a soil gives more clear idea of denseness Two types of sand having same void ratio may have entirely different state of denseness. However if two sands have same relative density, they usually behave in identical manner. The Relative Density of soil indicates how it would behave under the loads . If the deposit is dense it can take heavy loads with very little settlement. Depending upon the relative density, soils are generally divided into 5 categories:- RELATIVE DENSITY (%) DENSENESS <15 Very loose 15-35 Loose 35-65 Medium Dense 65-85 Dense 85-100 Very Dense
Anúncio