Understanding What is Soil Exploration: Objectives and Stages

Soil exploration is a critical aspect of construction and engineering projects, as it provides valuable information about ground conditions. In this blog, we will discuss what is soil exploration, its objectives, and the stages involved in the process. Understanding its importance can help professionals make informed decisions about the design and construction of safe and stable structures.
 

What is Soil Exploration

Soil exploration is the process of investigating and examining the subsurface conditions of a site to obtain information about the soil's properties, composition, and characteristics. This information is vital for the design and construction of safe and stable structures, as it helps engineers and architects make informed decisions about the type of foundation, construction materials, and techniques required for a specific project.

The process of soil exploration involves various methods and techniques, such as drilling boreholes, taking soil samples, and performing in-situ tests. These methods help in determining the soil's physical and engineering properties, such as bearing capacity, compressibility, and permeability. Moreover, it helps in identifying potential problems or hazards, such as unstable soil, high water table, or the presence of contaminants.

Objectives of Soil Exploration

Soil exploration serves various objectives that are crucial in understanding the properties and behaviour of the soil. Here are a few of them 

• 1) Determine soil properties

• To obtain information about the soil's physical and engineering properties, such as bearing capacity, compressibility, and permeability. This information is crucial for designing the foundation and other structural components of a project.

• 2) Determine groundwater table

• To identify the location of the groundwater table and its variations, which can significantly impact the design and construction of foundations, retaining walls, and other structures.

• 3) Identify potential problems

• To identify potential problems or hazards, such as unstable soil, high water table, or the presence of contaminants. Early identification of these issues allows engineers to develop appropriate solutions and mitigate risks.

• 4) Choose appropriate foundation types

• To select the most suitable type of foundation based on the site's soil conditions, ensuring the stability and longevity of the structure. It provides data required for designing the foundation and other structural components of a project.

• 5) Identify soil improvement techniques

• To select suitable soil improvement techniques, such as compaction, stabilisation, or reinforcement, to enhance the soil's engineering properties and performance.

• 6) Choose appropriate construction equipment

• To select the most suitable construction equipment based on the site's soil conditions, ensuring efficient and effective construction processes.

• 7) Estimate cost and feasibility

• To estimate the cost and feasibility of a project based on the soil conditions. By understanding the site's subsurface conditions, project managers can make more accurate cost estimates and assess the project's overall feasibility.

Stages of Soil Exploration

While understanding what is soil exploration, we also need to take into account its stages. It typically involves the following stages: 

• 1) Site Reconnaissance

• This stage involves a visual inspection of the site and its surroundings to gather information about the site's topography, vegetation, and nearby structures. This information helps in planning the soil exploration program and identifying potential access points and areas of concern and while building a house foundation. Site reconnaissance may also involve reviewing existing records and maps, such as geological maps, topographic maps, and aerial photographs, to gain a better understanding of the site's history and geological features.

• 2) Preliminary Site Exploration

• Preliminary site exploration is conducted for smaller projects like light structures, highways, and airfields. In this stage, preliminary tests and investigations are conducted to obtain a general understanding of the site's subsurface conditions. This may include drilling boreholes, taking soil samples, and performing in-situ tests, such as the Standard Penetration Test (SPT) or Cone Penetration Test (CPT).
  
  
• These tests provide initial data on the soil's properties and characteristics, which can be used to plan the detailed site exploration. Key information obtained includes approximate soil compressive strength, groundwater table position, depth and extent of soil strata, soil composition, depth of the hard stratum from ground level, and engineering properties of disturbed soil samples. Soil samples are collected from exploratory borings and shallow test pits, followed by simple laboratory tests such as moisture content, density, and unconfined compressive strength. Field tests, including penetration, sounding, and geophysical methods, are performed to gather information on soil's relative density and strength properties.

• 3) Detailed Site Exploration

• In-depth site exploration is best suited for intricate projects and substantial engineering works, such as heavy structures like dams, bridges, and skyscrapers. Based on the preliminary findings, a more detailed investigation is carried out to obtain specific information about the soil's properties and characteristics. This may involve additional drilling, sampling, and testing, as well as laboratory analyses of the collected samples.
  
  
• This advanced exploration phase includes performing numerous field tests, like in-situ vane shear tests and plate load tests, along with laboratory tests, such as permeability tests and compressive strength tests on undisturbed soil samples. These tests yield accurate values of soil properties, ensuring a thorough understanding of the site's subsurface conditions, which is crucial for designing and constructing complex and heavy structures.

• 4) Preparation of Report of Sub-Soil Exploration

• Once the previous stages are complete, a comprehensive report is prepared that includes the findings, test results, and recommendations for the project. This report is used by structural engineers and architects to design the foundation and other structural components of the project. To answer the question, "What is a structural engineer": a structural engineer is a specialist who skillfully employs the information from the soil exploration report to design the foundation and other structural elements, taking into account the site's unique characteristics. The report typically includes:

  • A description of the site and its surroundings

  • A summary of the site's geological and hydrological conditions

  • Details of the exploration methods and tests conducted

  • The results of the laboratory and in-situ tests

  • Interpretation of the test results and their implications for the project

  • Recommendations for the foundation design and construction techniques