The design process, according to Eurocode 7, requires the preparation and submission of an engineering report of foundation investigation to the client or owner. This report should encompass all relevant information and data gathered from various sources such as historical records, site observation, trial pits, boreholes, and laboratory tests. The report’s arrangement and contents will be the subject of this article’s discussion.
Preparing Engineering Report of Foundation Investigation
An engineering report on foundation investigation typically comprises several components that provide a comprehensive understanding of the site’s conditions and inform the foundation design and construction process.
The report typically starts with an introduction that provides an overview of the investigation’s purpose and scope. This section may also include information on the project’s background and the site’s location.
A general description of the site follows the introduction, providing details on the site’s size, boundaries, topography, and accessibility. This section may also describe any existing structures or infrastructure on or adjacent to the site.
The general geology of the area is another essential component of the report. It describes the geological history and characteristics of the region, including the types of rock formations and soils found in the area. This section provides context for understanding the soil conditions at the site and their potential impact on the foundation design.
The report then describes the soil conditions found in boreholes and trial pits, providing detailed information on the soil type, thickness, and depth, as well as any other relevant soil properties such as strength, stiffness, and permeability. This section may also include graphical representations of the soil profiles.
Laboratory test results are typically included in the report, providing additional information on the soil properties and characteristics. This section may include results from tests such as triaxial compression tests, shear tests, and consolidation tests.
The discussion of the investigation results in relation to the foundation design and construction is a critical component of the report. It analyzes the soil conditions and laboratory test results to identify any potential challenges or risks for the foundation design and construction process. This section may also include recommendations for how to address any issues that may arise.
Finally, the report includes recommendations and a conclusion. The recommendations may include specific foundation design parameters, such as pile spacing, depth, and size. The conclusion summarizes the key findings of the investigation and provides an overall assessment of the site’s suitability for the proposed foundation design and construction.
Introduction
The following major points need to be addressed in this section. First, it is important to clearly identify the client or individual for whom the investigation is being conducted. Secondly, the motivations behind the investigation should be explained. Thirdly, it should be described how the investigation was conducted. Fourthly, the timeframe during which the investigation was carried out should be specified.
The introduction should also clarify whether the investigation is limited and conducted solely to obtain data for evaluation by the designer, or if it is a comprehensive investigation involving boreholes, tests, and analysis of results to determine suitable design methods. If financial constraints or other factors have limited the investigation, the engineer should explicitly state these factors and any implications they may have on the investigation’s scope and accuracy.
General Description of the Site
This section is meant to document important features and data related to the site. Historical records can provide useful information about the site’s previous applications, and it’s important to include such information. Additionally, the configuration and surface features of the site should be recorded, including any old buildings, mine shafts, quarries, filled areas, watercourses, roads, tracks, hedges, and trees. It’s also important to document any instances of erosion, earthquakes, or slope instability that the site has experienced. Any cracks in surrounding buildings caused by settlements should also be thoroughly described.
General Geology of the Area
In an engineering report, it is necessary to include notes on the geology of the project site. This involves comparing available information from memoirs and maps to the data obtained from boreholes. It is important to consider any features such as faults, mines, springs, swallow holes, and quarries that may affect the foundation work.
The soil conditions found in the boreholes and trial pits should be described in a general manner, indicating changes in the levels of different strata, the groundwater table, and the ground configuration. If several boreholes have been taken, it is recommended to draw these in a section of the site to illustrate the configuration and level variation of the strata that is relevant to the engineering problem.
However, these diagrams should not include detailed information on the soil profile, such as changes in the groundwater table in successive strata. This is because such information could lead to costly errors. Therefore, a general description of the soil site is sufficient, without providing a detailed description of the soil profile.
Laboratory Test Results
The section of the engineering report will provide a brief overview of the types of tests conducted, without going into detailed test results. Any unusual or uncommon test results should be referenced in this section, while detailed test results will be included in the appendices. If any non-standard test procedures were used for specific tests, the procedure will be explained in this section as well.
Discussion of results of investigation in relation to the foundation design and construction
The discussion section of the engineering report for foundation design and construction is a critical component that should be clear and concise, avoiding the use of words such as “but” and “if”. To enhance readability and understanding, it is recommended to divide this section into different parts with appropriate subheadings.
Introduction: In this part of the discussion, a detailed description of the main structure and the related imposed loadings should be provided. This could include information about the purpose of the structure, its dimensions, and the anticipated loads it will bear.
General Ground Condition Assessment: This subsection should provide an assessment of the general ground conditions at the site where the foundation will be constructed. This could include information about the soil type, bearing capacity, and other relevant geotechnical data. Any potential challenges or issues related to the ground conditions should be addressed in a clear and concise manner.
Foundation Types: This subsection should outline the different types of foundations that could be used for the project, considering the specific requirements and constraints of the site. This could include options such as shallow foundations (e.g. spread footings, raft foundations) or deep foundations (e.g. piles, drilled shafts) and the factors influencing the selection of the appropriate foundation type.
Special Structures: If there are any special structures present at the site, such as an electricity generation station or turbine house, this subsection should discuss the specific requirements for their foundations. These structures often require special foundation designs due to their unique characteristics and loads they impose on the ground. Details of any specialized design considerations should be provided clearly and concisely.
Design Method: The last part of the discussion should outline the design method that will be used for the foundation. This could include information on the relevant design codes, software or analytical methods, and any specific design criteria or assumptions. The design method should be presented in a clear and organized manner to ensure understanding and readability.
By dividing the discussion section into these different parts with appropriate subheadings, the engineering report for foundation design and construction can be made more clear, readable, and understandable, allowing for a comprehensive and concise presentation of the relevant information. Efforts should be made to avoid the use of words such as “but” and “if” to maintain a concise and professional tone throughout the discussion section.
Note:
When discussing foundation options, it is advisable to avoid the topic of inappropriate foundations as it would not be productive. Instead, the discussion should clearly outline the type and depth of foundation, the allowable bearing pressure, and the anticipated settlement due to such pressure. It is also essential to highlight the advantages of adopting a deeper foundation to allow for higher bearing pressure or to reduce foundation settlement.
If pile foundation is chosen, the engineering report must specify the bearing strata onto which the pile will be driven, the likelihood of the pile penetrating the strata, the working load capacity per pile, and any potential impact on the surrounding structure. Furthermore, the report should include information on the difficulty of pile installation and any possible influence on the surrounding structure. It is important to provide these details to ensure that the foundation design meets the necessary standards and requirements.
Recommendations
The recommendation for the foundation design should be based on the facts that were uncovered in the report. To ensure the best outcome, it is important for the head of investigation and the design team to have effective communication throughout all stages of the project. This will help to ensure that the design is informed by the findings of the investigation and that any potential issues are addressed in a timely and efficient manner. By working together, the team can create a strong foundation that meets all necessary requirements and is capable of supporting the structure for the long term. Effective communication is key to the success of the project and should be prioritized throughout the entire process.
Conclusion
In the conclusion section, it is customary to summarize the major points of discussion that have been covered, particularly if the discussion has been extensive. This serves to remind the reader of the key takeaways from the discussion and to tie together the various strands of the argument that have been presented.
Furthermore, the conclusion should also include any findings that have been drawn from the investigation or analysis that has been conducted. These findings may relate to new insights that have been gained, conclusions that have been reached, or recommendations that have been made based on the evidence presented.
Overall, the conclusion serves as the final opportunity for the writer to make a lasting impression on the reader, and to emphasize the significance of the topic at hand. A well-written conclusion can leave a powerful and lasting impression on the reader, and can help to ensure that the key takeaways from the discussion are not forgotten.