මට හිතුන දේ, මට දැනුන දේ, මට ලැබුනු දේ, මම දන්න නොදන්න, මම හිතපු නොහිතපු, ඉගන ගත්තු, ඉගන ගත්න,අනන් මනන් ඔකොම.
Addsence
Friday, July 1, 2022
Rock Blasting ,ගල් පිපිරවීම,பாறை வெடிப்பு
ශ්රී ලංකාවේ සීග්ර වර්දනය හමුවේ ඉදිකිරීම කර්මාන්තය ප්රදාන ස්තානයක් දිනාගෙන තිබෙන අතර ඉදිකිරීම කර්මාන්තය සදහා අවශ්යවන්නාවු මූලික අමුදව්යයක් වන කලුගල් ලබා ගැනීම සදහා ගල් පිපිරවීම හෙවත් බෝර ගැසීම සිදුකරනු ලබයි.
තවද මහාමාර්ග ඉදිකිරීමේදී මාර්ග සීමාවේ පිහිටි කදු කපා සකසීමේදී එහිදී හමුවන්නාවු කලුගල් ඉවත්කිරීම සදහා ගල් පිපිරවීම ශිදුකරනු ලබයි.
Tuesday, February 15, 2022
Standard Penetration Test
Standard Penetration Test
The standard Penetration Test (SPT) is a widely used soil exploration tool that involves using a SPT hammer to drive a split barrel sampler at the bottom of a drill string to obtain soil samples. The number of blows required to penetrate the last 12" is the “N value”, which is related to soil strength.
Why Measure the Energy Transferred by the SPT Hammer?
Several different types of SPT hammers are used to conduct Standard Penetration Tests. Their varying efficiencies influence the “N value”. The measured “N value” is standardized by multiplying it by the ratio of the measured energy transferred to the rod to 60% of the theoretical potential energy. The standardization compensates for the variability of the efficiencies of different SPT hammer types, and improves the reliability of soil strength estimates used in geotechnical applications.
N60 is what a safety hammer (cathead and rope) N value is estimated to be uncorrected. An auto hammer is estimated to be about 80% efficient. 1.333 times more than a safety hammer. The N value needs to be corrected to a normalized N60. We find that all SPT hammers, including auto hammers, can vary rig to rig, operator to operator, job site to job site.
On large or critical projects, energy testing may verify SPT performance to allow for increased design confidence and economy.
To use correlations, LRFD Eq. 10.4.6.2.4–2: requires correction to reflect actual energy
N60 = (ETR/60) x N
N60 = SPT blow count corrected for hammer efficiency
ETR = Hammer Energy Transfer Ratio
N = uncorrected (raw) SPT blow count
- Perform measurements for at least 3 depths of quality data, with 5 depths preferred
- Tests should be limited to moderate N-values ranges between 5 and 50
- Energy evaluation of the hammer system is more reliable when the length (LE) is (30 ft) to (40 ft) or more
- Le = length between the location of the transducers on the instrumented subassembly and the bottom of the sampler
AASHTO – For a test to be satisfactory, an N-value of at least 10 must be obtained at each depth and a total of 50 measurements must be recorded for a particular sequence of depths
Tuesday, October 5, 2021
Depth Of Foundation
Bearing Capacity of Soil
Density of Soil
Water Table
Self weight of Structure
Live Load of Structure
Wind Load & Seismic Load (Earthquake)
Rankine's Formula
Df=Minimam Depth of Foundation
p=Bearing Capacity of soil
w=density of soil
θ=Angle of proposed Soil
Complex
Given data:
Load on the foundation ( p ) = 370KN/m2
Unit weight of soil (w) = 17KN/m3
The angle of repose of soil (θ )= 35°
Now, we will calculate the minimum depth of foundation (Df )by using Rankine's formula.
Where,
Df = [( p ÷ w ) × ( 1- sinθ ÷ 1+sinθ )2]
= [( 370 ÷ 17 ) × ( 1- sin35° ÷ 1+sin35° )2]
= [(21.764 ) × ( 1- 0.5735 ÷ 1+ 0.5735 )2]
= [ 21.764 × ( 0.4265 ÷ 1.5735 )2]
= [ 21.764 × (0.271)2]
= [21.764 × 0.07346]
= 1.598m.
The minimum depth of foundation for the above-given data is calculated as 1.598 by using Rankine's formula.
In the following table, I have given the angle of repose & the unit wt. of different types of soil.
Sl. No. |
Type of soil |
Unit wt. of soil in KN/m3 |
Angle of repose |
1 |
Moist soil |
16.5-17.5 |
40°-45° |
2 |
Wet soil |
17-18 |
15°-20° |
3 |
Dry soil |
16-17 |
20°-30° |
4 |
Wet sand |
18-19 |
15° - 25° |
5 |
Dry sand |
15 -16 |
25° - 35° |
6 |
Gravel |
17-18 |
40°-45° |
7 |
Gravel sand |
18-19 |
25°-35° |
8 |
Wet clay |
18.5-19 |
15° |
9 |
Moist clay |
17.5-18.5 |
35°-40° |
10 |
Dry clay |
17-17.5 |
30°-35° |
11 |
Mud |
16-18.5 |
0° |
Note: The above-given data are the average values for the general considerations.
I recommend the soil test of the foundation, to get the accurate values of the angle of repose & unit wt. of that particular soil.
Usually, for residential buildings, the depth of foundation falls between 1.2m. to 2.1m. ( i.e. 4ft. - 7ft.).
What are the factors that affect the depth of foundation?
The factors that affect the foundation depth are,
1. Structural load:
If the foundation has to withstand more loads, the depth of the foundation increases. More the load the foundation has to carry, the more will be the foundation depth.
2. Density of soil :
The higher the density or unit wt. of soil, the less will be the foundation depth. In other words, foundation depth is inversely proportional to the density of soil for a given load.
3. Type of soil:
The angle of repose of different types of soil vary, which affects the depth of the foundation.
4. Water content of soil:
The water content in the soil decides the density & angle of repose of the soil. So the depth of the foundation changes depending upon the water table of the foundation site & the amount of moisture content in the soil.
5. Refilled soil:
If the foundation base is prepared by refilling the soil over the existing ground surface, the foundation may take more depth, depending upon the degree of compaction & final density of the refilled material.
Here is a list of various materials and their angle of repose.[3] All measurements are approximated.
Material (condition) | Angle of Repose (degrees) | |||
---|---|---|---|---|
Sand (water filled) | 15–30° | |||
Clay (wet excavated) | 15° | |||
Gravel (natural w/ sand) | 25–30° | |||
Clay (dry lump) | 25–40° | |||
Urea (Granular) | 27° [5] | |||
Wheat | 27° | |||
Clover seed | 28° | |||
Flour (corn) | 30–40° | |||
Asphalt (crushed) | 30–45° | |||
Bran | 30–45° | |||
Earth | 30–45° | |||
Malt | 30–45° | |||
Sand (dry) | 34° | |||
Granite | 35–40° | |||
Coffee bean (fresh) | 35–45° | |||
Snow | 38°[4] | |||
Ashes | 40° | |||
Bark (wood refuse) | 45° | |||
Chalk | 45° | |||
Coconut (shredded) | 45° | |||
Flour (wheat) | 45° | |||
Gravel (crushed stone) | 45° | |||
Sand (wet) | 45° | https://civilplanets.com/types-of-loads/#Wind_Load |
Friday, June 18, 2021
Water Quality Test Concrete Production
WATER QUALITY TEST |
||
Test |
Test Method |
Unit |
pH at 22.3 °c |
ASTM D 1293-99 |
- |
Chloride (Cl) Content |
ASTM D 512-04 |
mg/L |
Sulphate (S042-) Content |
ASTM D 516-07 |
mg/L |
Total Suspended Solids (TSS) |
APHA-2540-D |
mg/L |
Total Dissolved Solid (TDS) |
APHA-2540-C |
mg/L |
Carbonate (C032 ) Content |
USGS - 06 Method |
mg/L |
Bicarbonate (HCQ3-) Content |
USGS - 06 Method |
mg/L |
Electrical Conductivity |
APHA 2510-B |
µSiem |
Turbidity |
USEPA 180.1 |
NTU |
Phosphate (as P205) |
APHA-4500-P-E |
mg/L |
Nitrate (as N03} |
APHA 4500-N03"-B |
mg/L |
Humic matter |
BS EN 1008:2002 |
- |
Tuesday, April 20, 2021
Asphalt Binder Course Testing
REFERENCED SPECIFICATIONS |
|||
No |
Test Item |
Referenced Specification |
|
01 |
Preparation of Material and Marshal Compaction |
Asphalt Concrete M ix Design Manual Series No 02 (6th Edition) |
|
02 |
Maximum Theoretical Specific Gravity |
ASTM 02041-78 |
|
03 |
Grading of Course Aggregate |
ASTM C·136 I/ASTM C-1 17 |
|
04 |
Grading of fine Aggregate |
ASTM C-136 I ASTM C-1 17 |
|
05 |
Specific Gravity of Aggregate |
ASTM C-127/C-128 |
|
06 |
Water Abortion of Aggregate |
ASTM C-127/C-128 |
|
07 |
Specific Gravity of Bitumen |
AST1'.1 D 70-86 |
|
08 |
Softening Point |
ASTM D 36-95 |
|
09 |
Pe11etration of Bitumen |
ASTM D 5-97 |
|
10 |
Flash Point |
ASTM D 92-96 |
|
11 |
Loss on Heating for 5hrs .at 163·C |
ASTM D 6-95.ASTM D 5-97 |
|
12 |
Ductility at 25oC |
ASTM D 113-99 |
|
13 |
Coating & stripping test |
ASTM D 1644 |
Density of Construction Materials / ඉදිකිරීම් ධ්රව්ය යන්හි ඝනත්වය / கட்டுமான பொருட்களின் அடர்த்தி
Density of Civil Martial's Construction Materials Density (Kg /m3) Density (lb/ft3) ...
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