Civil Engineering

Thursday, 20 September 2018

5 Major Difference Between Bridge And Culvert

9/20/2018 07:44:00 pm

Difference Between Bridge And Culvert


The cross drainage structure which is constructed for carrying road or railway across a natural drainage or compression is called bridge.

The Bridge having total span up to 6 m is called culvert.
All bridges are not culverts.

All culverts are bridges.

It is constructed where a drain or depression of any width crosses the roadway or railway.

It is constructed where a small drain or depression crosses the roadway or railway.
It may consist of elaborate super structure.

It consists of minor structure.

Large bridges are generally made of R.C.C steel ,pre-stressed concrete.
Culverts are generally made of brick or stone masonry, plain or reinforced concrete, Hume pipe.

Wednesday, 19 September 2018

Field Measurement of Shear Strength of Cohesive Soil By Vane Shear Test

9/19/2018 11:59:00 am

Vane Shear Test On Soil

Vane shear test is a simple and quick test,used either laboratory or in the field.

Aim of Vane shear test 

To determine un-drained shear strength of cohesive soil.

Testing Equipment For vane shear Test

⇰ A vane shear testing equipment consists of four thin plates,called vanes,welded orthogonally to a steel rod .
⇰ A torque measuring arrangement ,such as a calibrated torsion spring is attached to the rod.The steel rod is rotated by worm gear and worm wheel arrangement.

Procedure of Vane Shear Test

⇰ A pit is first of all made into the ground up to a depth at which the shear strength is to be tested.

⇰ The vane tester is then pushed or driven carefully into the soil below the bottom of the pit,to a depth somewhat grater than the length of the vane.

⇰ The torque rod is now rotated (usually 1° per minute).The rotation is continued till the soil falls,Which will be indicated by the sudden decrease of torque without any back movement of torque wheel.

⇰ The maximum torque (T) given till failure is measured and recorded.
The shear strength (𝛕f) is calculated by using the following equation;

𝛕f = 2T / πd2[ H + d/3]

Where ,H = Height of the vane
And, d = Diameter of the vane

Wednesday, 12 September 2018

Comparison Between Conservancy System & Water Carriage System

9/12/2018 12:00:00 pm

Conservancy System

1. This system does not permit compact design of buildings.
2. This system is non hygienic.
3. Large area is required for treatment and disposal.

4. Labor force required is much more
5. There are chances for the out break of epidemic.
6. Under ground sources of water may be polluted.
7. It requires small quantity of water.
8. It is cheap in initial cost.
9. No skilled labor and technical persons are required for the maintenance of this system.
10. This system is considered suitable for rural and undeveloped areas.

Water Carriage System

1. This system permits compact design of buildings.
2. This system is hygienic.
3. Less area is required for treatment and disposal.
4. Only few labor are required.
5. The risk of outbreak of epidemic is greatly reduced.
6. There are no chances of nuisance on the streets.
7. It requires large quantity of water.
8. The initial cost is very high.
9. Highly skilled labor and technical persons are required for the maintenance of this system.
10. This system is considered suitable for urban area.

Monday, 10 September 2018

12 Factors Considering Selection of Site For a Bridge & Culvert construction

9/10/2018 10:40:00 pm
The selection of site for bridges and culverts is an art and requires considerable investigations. A few points that deserve attention are given below.

12 Factors considering Selection of Site For a Bridge & Culvert Construction

1. A site which is on a straight reach of the drainage should be selected. The curved reach of drainage should be avoided as far as possible.

2. The stream at bridge side should have permanent ,firm,straight and high banks.

3. The stream at Bridge site should be well defined and as narrow as possible.

4. The site should be sufficiently away from the confluence point.

5. There should be no scouring and silting of the stream at bridge site.

6. A site which offers a square crossing should be selected as far as possible.

7. The site which offers more advantageous foundation condition should be preferred.

8. A site which is sufficiently away from the landslides and subsidence should be preferred.

9. The site should not interfere adversely with any other bridges, weirs,regulators,dams etc in the vicinity.

10. There should be minimum obstruction to natural water way at the bridge site.

11. The stream at bridge site should be free from costly river training works.

12. The bridge should provide proximity to the direct alignment of the communication route to be served.

Monday, 3 September 2018

Separate Sewer System And Their Advantages & Disadvantages

9/03/2018 10:08:00 pm
In this system two sets of sewers are laid . One is used for carrying sewage and the other is used for carrying storm water . The sewage is carried to the treatment plant and finally disposed off after treatment. The storm water is directly discharged into the river or stream.

Favourable For Separate Sewer System

The separate sewer system is favoured under the following condition:
1. If the area is flat.
2. When the rainfall is uneven or it is heavy for a short duration.
3. When it is necessary to pump the sanitary sewage.
4. If the area possesses steep slope.
5. If sewer are to be laid through hard rocky soil.
6. If sewers are to be laid before the area is developed.
7. If it is not possible to lay sewers at suitable gradients.

Advantages of separated sewer system

Following are the advantages of separate sewer system
1. The load on treatment unit becomes less.
2. The storm water is not unnecessarily polluted.
3. The sewers are small in size.
4. The storm water can be discharged into natural streams without any treatment.
5. This system proves to be economical when pumping is required for the lifting of sewage.

Disadvantages of separated Sewer system

Following are the disadvantages of separated sewer system
1. The cleaning of sewers is difficult as they are of small in size.
2. The maintenance cost is high.
3. The self cleaning velocity is not easily achieved.

1.Partially Separate Sewer System And Their Advantages & Disadvantages
2.Combined Sewer System And Their Advantages & Disadvantages

Friday, 31 August 2018

Length Of Transition Curve Design Method

8/31/2018 04:09:00 pm

Length Of Transition Curve

In this article i will show you how to design the length of transition curve,or say how to calculate or determine the length of transition curve.

The length of transition curve is designed to fulfill the three condition as mention below.The length of transition curve for design should be highest of the three values.

1.The rate of change of centrifugal acceleration to be developed gradually.From this consideration the length transition curve is given by the following equation:

Ls = 0.0215 V³/ CR
Where ,Ls = Length of transition curve in m, V = Speed of vehicle in Km/h , C = Rate of change of centrifugal acceleration, R = Radius of circular curve in m .
The minimum and maximum values of C are limited to 0.5 & 0.8 respectively.

2.The rate of introduction of designed super elevation to be at a reasonable rate.From this consideration the length of transition curve is given by the following :

Ls = e.N (W + We)/2
Where, e = The rate of designed super elevation ,W = Normal pavement width in m , We = Extra widening pavement at the circular curve in m. 1/N = Rate of change of super elevation (Minimum value of N is 150 to 60 ).

3.By Empirical formula: According to I.R.C standards, the length of horizontal transition curve should act ,than the value given by the following equations:

a)For plain and rolling terrain ,Ls = 2.7 V²/R
b)For mountainous and steep terrain, Ls = V²/R

Thursday, 30 August 2018

Recommended Gradient as Per I.R.C

8/30/2018 07:51:00 pm

Recommended Gradient

1. Plain or Rolling Terrain

Ruling gradient:- 1 in 30 (3.3%).
Limiting gradient:- 1 in 20 (5%).
Exceptional gradient:- 1 in 15 (6.7%).

2.Mountainous Terrain

Ruling gradient:- 1 in 20 (5%).
Limiting gradient:- 1 in 16.7 (6%).
Exceptional gradient:- 1 in 14.3 (7%).

3.Steep Terrain

Ruling gradient:- 1 in 16.7 (6%).
Limiting gradient:- 1 in 14.3 (7%).
Exceptional gradient:- 1 in 12.5 (8%).
Note: The maximum gradient at hairpin bend shall be 2.5 % for mountainous and steep areas.