Answer To: File attached
Bhaumik answered on Mar 09 2024
ASSIGNMENT
TASK 1
a) To classify the soil type based on the provided composition of clay, silt, and sand, we will use the USDA soil texture triangle. The soil texture triangle is a graphical representation that helps classify soil based on the percentage of sand, silt, and clay it contains.
1. Determine Percentages:
According to the given data:
· Clay: 38%
· Silt: 35%
· Sand: 27%
2. Plot the Points on the Soil Texture Triangle:
The USDA soil texture triangle typically consists of three axes representing sand, silt, and clay percentages. To classify the soil, we locate the point corresponding to the percentages of clay, silt, and sand on the triangle.
· Start by locating the point for clay (38%) on the bottom axis.
· Then, locate the point for silt (35%) on the right axis.
· Finally, locate the point for sand (27%) on the left axis.
3. Join the Points:
Once all three points are located, draw lines connecting them. The point where these lines intersect within the triangle represents the soil type.
4. Identify the Soil Type:
By identifying where the lines intersect on the triangle, we can determine the soil type.
5. Discussion:
Discuss the characteristics of the identified soil type, including its properties, strengths, and potential implications for construction.
Here is an example of how to proceed:
a. USDA Soil Texture Triangle Analysis:
· Clay: 38%
· Silt: 35%
· Sand: 27%
Plotting the points for clay (38%), silt (35%), and sand (27%) on the USDA soil texture triangle, we find that they intersect within the region corresponding to a loam soil type.
b. Discussion:
· Loam Soil Type: Loam soil is a balanced mixture of sand, silt, and clay, with moderate water retention and good fertility. It offers good drainage and aeration, making it suitable for a wide range of construction projects.
c. Report Summary: The soil at the proposed construction site has been classified as loam soil based on the analysis of clay, silt, and sand percentages. This soil type offers favorable characteristics for construction, including moderate water retention, good drainage, and adequate fertility.
b) To determine the site class based on the identified soil type (loam soil), we refer to the National Construction Code (NCC), specifically Volume Two, Part 3.2.4, which provides guidance on site classification for building construction.
In the NCC, site classification is typically based on the soil type and its associated properties, such as its ability to withstand movement or deformation under load. Different soil types are assigned specific site classes, ranging from Class A to Class S, with Class A representing the most stable soils and Class S representing the least stable or highly reactive soils. Since we have identified the soil type as loam, we need to determine the corresponding site class. Typically, loam soil falls into Class A or Class S, depending on its specific characteristics and regional variations. Given that loam soil is generally considered to be moderately stable, it is likely to be classified as Class A in the NCC, indicating low risk of ground movement. However, it's important to note that site classification can vary based on regional factors, geological conditions, and specific project requirements.
Here is how we can interpret the soil classification based on the given assumptions:
· Slightly reactive clay sites: up to 40% clay
· Moderately reactive clay or silt sites: up to 54% clay
· Highly reactive clay sites: up to 60% clay
· Extremely reactive sites: above 60% clay
Given the composition of the soil as follows:
· Clay: 38%
· Silt: 35%
· Sand: 27%
We can see that the clay content falls within the range for moderately reactive clay or silt sites (up to 54% clay). Therefore, the site class for this soil type would likely be classified as **moderately reactive clay or silt sites** according to the NCC guidelines.
This classification suggests that the soil has moderate reactivity to moisture changes, which could potentially affect the stability of the construction site. Design and construction considerations need to account for the soil's reactivity to minimize any potential issues related to ground movement or foundation stability.
c) Given that the obtained site class based on the soil composition falls under moderately reactive clay or silt sites, it is crucial to select an appropriate type of footing that can effectively support the structure and mitigate any potential issues related to soil movement.
For moderately reactive clay or silt sites, a suitable type of footing would be a **raft foundation**. Raft foundations, also known as mat foundations, are large concrete slabs that cover the entire footprint of the structure. They distribute the building load over a wide area of soil, reducing the pressure on the underlying soil and minimizing the potential for differential settlement.
Justification for selecting raft foundation:
1. Uniform Distribution of Load: Raft foundations spread the load of the structure uniformly over the entire area of the foundation. This helps in reducing the stress on the underlying soil, which is particularly beneficial in moderately reactive clay or silt sites where differential settlement can occur due to uneven loading.
2. Mitigation of Differential Settlement: Since raft foundations cover the entire footprint of the structure, they are effective in mitigating the effects of differential settlement. This is essential in sites with moderately reactive clay or silt, where variations in soil moisture content can lead to differential movement of the foundation.
3. Increased Stability: Raft foundations provide increased stability by utilizing the entire soil mass beneath...