Introduction:
Earthwork preparation is an important process in construction projects. It involves several steps, such as equipment use, testing, and level recording, among others. In this blog post, we will discuss the steps involved in earthwork preparation, the equipment used, testing methods, and level recording.
Steps Involved in Earthwork Preparation:
Site Preparation: Before any earthwork can be done, the site needs to be prepared. This involves clearing the site of any vegetation, debris, or other obstructions that may be in the way.
Excavation: The next step is excavation, which involves removing soil and other materials from the site to create a level surface. This is usually done using heavy machinery such as excavators, backhoes, and bulldozers.
Compaction: After excavation, the soil needs to be compacted to ensure a stable base for the construction. This is done using a compactor, which applies pressure to the soil to remove any air pockets.
Grading: Once the soil is compacted, the site needs to be graded to create a level surface. This is done using a grader, which levels the soil to the desired grade.
Testing: Throughout the earthwork preparation process, the soil is tested to ensure that it meets the required specifications. This involves testing for soil density, moisture content, and other factors that may affect the stability of the soil.
Final Inspection: Once the earthwork preparation is complete, a final inspection is done to ensure that everything has been done according to the required specifications.
Equipment Used in Earthwork Preparation:
Excavators: These are large machines used for excavation, which involves removing soil and other materials from the site.
Backhoes: These are smaller machines that are used for excavation and are ideal for tight spaces.
Bulldozers: These are heavy machines used for moving soil and other materials around the site.
Compactors: These machines are used to compact the soil after excavation, ensuring a stable base for the construction.
Graders: These machines are used to grade the soil to the desired level.
Testing Methods in Earthwork Preparation:
Soil Density Testing: This involves measuring the density of the soil using a compaction test.
Moisture Content Testing: This involves measuring the amount of moisture in the soil, which can affect the stability of the soil.
Atterberg Limits Testing: This involves testing the plasticity of the soil, which can determine the suitability of the soil for construction.
Level Recording in Earthwork Preparation:
Leveling Equipment: This involves using a leveling instrument to determine the elevation of the soil.
Digital Levels: These are modern instruments used to measure the elevation of the soil digitally.
Conclusion:
In conclusion, earthwork preparation is an important process in construction projects. It involves several steps, such as site preparation, excavation, compaction, grading, testing, and final inspection. The equipment used includes excavators, backhoes, bulldozers, compactors, and graders. Testing methods include soil density testing, moisture content testing, and Atterberg limits testing. Level recording involves using leveling equipment or digital levels to measure the elevation of the soil. By following these steps, construction projects can ensure that the soil is properly prepared for the construction process.
The Ministry of Road Transport and Highways (MoRTH) has provided guidelines for the design and construction of roads, including the thickness of the earthwork layer. The thickness of the earthwork layer depends on the type of soil and the traffic expected on the road. The MoRTH has provided a classification system for the type of soil, which is used to determine the thickness of the earthwork layer.
According to MoRTH, the thickness of the earthwork layer should be as follows:
For soils with low plasticity and less than 35% of fine content:
For National Highways (NH) and State Highways (SH), the minimum thickness of the earthwork layer should be 300mm.
For other roads, the minimum thickness of the earthwork layer should be 250mm.
For soils with high plasticity and more than 35% of fine content:
For National Highways (NH) and State Highways (SH), the minimum thickness of the earthwork layer should be 450mm.
For other roads, the minimum thickness of the earthwork layer should be 350mm.
It is important to note that the above guidelines are the minimum thicknesses of the earthwork layer, and the thickness may need to be increased depending on the traffic load and other factors such as soil moisture content and compaction level.
In conclusion, the thickness of the earthwork layer as per MoRTH guidelines depends on the type of soil and the expected traffic load. It is important to follow these guidelines to ensure the proper design and construction of roads.
earthwork layer thickness as per MoRTH guidelines:
Soils with low plasticity and less than 35% of fine content:
Soils with low plasticity and less than 35% of fine content are classified as Group A-2-4 and Group A-2-5. These types of soils are typically non-cohesive, and they do not retain water well. As a result, they tend to have poor load-bearing capacity.
To compensate for the poor load-bearing capacity of these soils, the earthwork layer thickness for National Highways (NH) and State Highways (SH) is set at a minimum of 300mm. For other roads, the thickness is set at a minimum of 250mm. These thicknesses are recommended to provide adequate support to the road and ensure its stability.
Soils with high plasticity and more than 35% of fine content:
Soils with high plasticity and more than 35% of fine content are classified as Group A-7-6 and Group A-7-5. These types of soils are typically cohesive and retain water well. As a result, they tend to have better load-bearing capacity than non-cohesive soils.
However, these soils are also more susceptible to deformation under heavy loads. To compensate for this, the earthwork layer thickness for National Highways (NH) and State Highways (SH) is set at a minimum of 450mm. For other roads, the thickness is set at a minimum of 350mm. These thicknesses are recommended to provide sufficient support to the road and ensure its stability under heavy loads.
It is important to note that the earthwork layer thicknesses provided by MoRTH are minimum recommendations. Depending on factors such as soil moisture content and compaction level, the thickness of the earthwork layer may need to be increased to ensure the stability of the road. Additionally, these guidelines are subject to change and should be reviewed periodically to ensure that they are up to date.
Earthwork as per MoRTH:
MoRTH provides guidelines for the design and construction of roads, including the earthwork requirements. The earthwork in highway projects involves the excavation and embankment of soil for the construction of roads, embankments, and other structures.
The guidelines for earthwork in highway projects as per MoRTH are as follows:
Excavation for the road prism should be carried out to the required depth and width.
The excavated soil should be transported to the embankment site and compacted in layers not exceeding 200mm thickness.
The soil should be compacted to achieve the required density as per MoRTH specifications.
The compacted embankment height should not exceed the maximum limit specified by MoRTH.
The embankment should be finished to the specified cross-section and slope.
The road surface should be finished to the specified cross-section and surface regularity.
Earthwork as per IS code IRC:
The Indian Roads Congress (IRC) is a professional body that provides guidelines for the design, construction, and maintenance of roads and highways in India. The IRC provides guidelines for earthwork in highway projects in the form of the IRC:37-2012 manual.
The IRC guidelines for earthwork in highway projects are as follows:
The excavation should be carried out to the specified width and depth, and the soil should be transported to the embankment site.
The soil should be spread in layers and compacted to achieve the required density.
The compaction should be carried out using suitable compaction equipment as per IRC specifications.
The embankment height should not exceed the maximum limit specified by IRC.
The embankment slope should be finished to the specified gradient.
The road surface should be finished to the specified cross-section and surface regularity.
In conclusion, both MoRTH and IS code IRC provide guidelines for earthwork in highway projects. These guidelines include excavation, transportation, embankment construction, and finishing requirements for the road prism and embankment. It is important to follow these guidelines to ensure that the earthwork is carried out correctly and the road is stable and safe for use.
Level recording is an important process that is carried out during the construction of highways, buildings, and other structures. The process involves recording the elevation or height of different points on the construction site relative to a known benchmark or reference point. This is done to ensure that the construction is carried out at the correct elevation and to ensure that the final structure is level and stable.
The level recording process typically involves the following steps:
Setting up the survey equipment: The survey equipment used for level recording includes a level instrument, a levelling staff, and a tripod. The level instrument is mounted on the tripod, and the levelling staff is held vertically by a person at the point where the height needs to be recorded.
Establishing a benchmark: A benchmark is a reference point with a known height above a fixed datum, such as mean sea level. The benchmark is typically established by a government agency or a professional surveyor. The benchmark is used as a reference point for all height measurements on the construction site.
Carrying out the height measurement: The level instrument is used to measure the height of the levelling staff at different points on the construction site. The height is recorded in relation to the benchmark.
Recording the data: The height measurements are recorded in a survey notebook or a computer software program. The data is typically recorded in a table format that includes the point number, the height measurement, and the distance from the benchmark.
Analyzing the data: The height measurements are analyzed to ensure that the construction is being carried out at the correct elevation. The data is used to calculate the height differences between different points on the construction site, and any discrepancies are identified and corrected.
Adjusting the construction: If there are any discrepancies in the height measurements, the construction is adjusted accordingly to ensure that the final structure is level and stable.
In conclusion, level recording is an important process in construction projects, and it involves measuring the height of different points on the construction site relative to a known benchmark. The process helps ensure that the construction is carried out at the correct elevation and that the final structure is level and stable.
In surveying, HI stands for Height of Instrument. It is the height of the optical instrument, such as a level or a theodolite, above the benchmark or a reference point. BS stands for Backsight, which is the reading taken on a staff held on a point of known elevation. FS stands for Foresight, which is the reading taken on a staff held on a point of unknown elevation. IS stands for Intermediate Sight, which is a reading taken on a staff between the BS and FS points.
Here is an example of HI calculation using BS, IS, and FS readings:
Assume that the benchmark elevation is 100 Mtr RL, and the HI of the instrument is 1.2 meters.
Backsight Reading: 1.50 meters
Intermediate Sight Reading: 1.45 meters
Foresight Reading: 1.60 meters
To calculate the Reduced Level (RL) of the foresight point, we need to apply the following formula:
RL of Foresight = RL of Instrument + Backsight - Foresight
Here, the RL of the instrument is the benchmark elevation + HI = 100 Mtr RL + 1.2 meters = 101.2 meters RL.
Using the given values, we can calculate the RL of the foresight point as follows:
RL of Foresight = 101.2 + 1.50 - 1.60
= 101.1 meters RL
To check the accuracy of the calculation, we can also calculate the RL of the intermediate sight point:
RL of Intermediate Sight = RL of Instrument + Backsight - Intermediate Sight
RL of Intermediate Sight = 101.2 + 1.50 - 1.45
= 101.25 meters RL
The difference between the RL of the intermediate sight and the foresight points should be equal to the difference between the backsight and foresight readings. In this case, the difference is:
(Backsight - Foresight) - (Intermediate Sight - Foresight) = (1.50 - 1.60) - (1.45 - 1.60) = 0.05 meters
This difference is within the acceptable tolerance level, which means that the level calculation is accurate.
In conclusion, the HI calculation using BS, IS, and FS readings involves calculating the RL of the foresight point using the formula RL of Foresight = RL of Instrument + Backsight - Foresight. It is important to check the accuracy of the calculation by comparing the difference between the backsight and foresight readings with the difference between the intermediate sight and foresight readings.
I apologize for the confusion in my previous response. "FLY" is not a term used in surveying, and I am not sure what you meant by it. However, I will provide a detailed explanation of the process of establishing a temporary benchmark (TBM) in surveying.
Establishing a TBM involves the following steps:
Choose a suitable location: The TBM should be established at a location that is easily accessible, stable, and close to the construction site. It should also be visible and easily identifiable to the surveyors.
Establish the benchmark point: The benchmark point is the point on the ground where the TBM is established. The point should be marked with a metal peg, nail or other suitable marker. The benchmark point should be leveled and have a known elevation, usually obtained from an existing permanent benchmark.
Set up the instrument: Set up the level instrument over the benchmark point, and take a backsight reading on a staff held on the benchmark point. Record the reading as "BS."
Move the instrument to the next location: Move the level instrument to the next location where a height measurement is required. This could be a point on the ground where excavation or backfilling is to be done, or a point on a structure that is being constructed.
Take a foresight reading: Take a foresight reading on a staff held on the next location. Record the reading as "FS."
Calculate the height difference: Subtract the foresight reading from the backsight reading to get the height difference between the two points. This is known as the "rise" or "fall." Record the difference as "Rise/Fall."
Calculate the elevation of the next point: Add the height difference to the elevation of the benchmark point to get the elevation of the next point. Record the elevation as "RL."
Repeat the process: Move the level instrument to the next location and repeat the process until all required points have been surveyed.
Example:
Assume that the benchmark elevation is 100 meters RL, and the backsight reading on the benchmark is 1.25 meters. The foresight reading at the next location is 1.80 meters.
Rise/Fall = FS - BS = 1.80 - 1.25 = 0.55 meters
RL of next point = RL of benchmark + Rise/Fall = 100 + 0.55 = 100.55 meters
Continue the process at the next location, taking backsight and foresight readings and calculating the height difference and the elevation of the next point.
In conclusion, establishing a temporary benchmark (TBM) involves setting up a level instrument, taking backsight and foresight readings, and calculating the height difference and the elevation of the next point. This process is repeated at each location where a height measurement is required.
Sure, I'd be happy to provide a more detailed example of how to establish a TBM in surveying. Let's assume that we need to establish a TBM for a construction project on a piece of land. The goal is to create a level surface for the construction of a building, and the design requires a specific elevation for the finished surface. The surveying team has been tasked with establishing a TBM to ensure that the level surface is at the correct elevation.
Step 1: Choose a Suitable Location
The surveying team has chosen a location that is close to the construction site and easily accessible. They have selected a point near the center of the site that is free from any obstructions and has a clear line of sight in all directions. They have also marked the location with a metal peg to ensure that it is easily identifiable.
Step 2: Establish the Benchmark Point
The surveying team has obtained the elevation of a permanent benchmark near the site and has determined that it is at an elevation of 50 meters RL. They have set up the level instrument over the TBM location and have leveled it using the built-in bubble level. They have then taken a backsight reading on a staff held on the permanent benchmark and have recorded the reading as 3.50 meters.
Step 3: Set up the Instrument
The surveying team has set up the level instrument over the TBM location and has leveled it using the built-in bubble level. They have then taken a backsight reading on a staff held on the permanent benchmark and have recorded the reading as 3.50 meters.
Step 4: Move the Instrument to the Next Location
The surveying team has moved the level instrument to the next location where they need to establish the elevation. In this case, it is a point on the ground where excavation is to be done. They have placed a staff at the point and have taken a foresight reading. The reading is 2.70 meters.
Step 5: Take a Foresight Reading
The surveying team has taken a foresight reading on the staff held at the excavation point. They have recorded the reading as 2.70 meters.
Step 6: Calculate the Height Difference
The surveying team has subtracted the foresight reading from the backsight reading to get the height difference between the two points. The calculation is as follows:
Rise/Fall = FS - BS
Rise/Fall = 2.70 - 3.50
Rise/Fall = -0.80 meters
The negative sign indicates that the excavation point is lower than the benchmark point.
Step 7: Calculate the Elevation of the Next Point
The surveying team has added the height difference to the elevation of the benchmark point to get the elevation of the excavation point. The calculation is as follows:
RL of next point = RL of benchmark + Rise/Fall
RL of next point = 50 - 0.80
RL of next point = 49.20 meters
Step 8: Repeat the Process
The surveying team has repeated the process at each location where a height measurement is required. They have moved the level instrument to the next location, taken backsight and foresight readings, and calculated the height difference and the elevation of the next point.
For example, at the next location, they have taken a foresight reading on a staff held on a point where backfilling is to be done. The reading is 3.20 meters. The backsight reading on the TBM is still 3.50 meters. The height difference is calculated as follows:
Rise/Fall = FS - BS
Rise/Fall = 3.20 - 3.50
Rise/Fall = -0.
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