How to Prepare Engineering Report of Foundation Investigation?

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According to Eurocode 7, engineering report of foundation investigation need to be prepared and submitted to the client or owner as part of design process. The report should consider all information and data from historical records, site observation, trial pits, boreholes, and laboratory tests. In this article, the arrangement and contents of engineering report of foundation investigation will be discussed.

Preparing Engineering Report of Foundation Investigation

Engineering report of foundation investigation is composed of the following components

• Introduction
• General description of the site
• General geology of the area
• Description of the soil conditions found in boreholes and trial pits
• Laboratory test results
• Discussion of results of investigation in relation to the foundation design and construction
• Recommendation
• Conclusion

Introduction

There are number of major points which need to be explained in this part and these points are as follow:

• It should be stated clearly the client or individual for whom the investigation is conducted.
• Motivations to conduct the investigation.
• How the investigation conducted.
• Specify the time at which the investigation carried out.
• The introduction should explain whether the investigation is limited and carried out to achieve certain data to perform evaluation by the designer, or it is a thorough investigation with boreholes, tests, and analysis of results to consider suitable methods of design.
• If the investigation is limited due to financial restrictions or other factors and the engineer find out that the investigation is insufficient, then he should state the factors that cause limitation of the investigation.

General Description of the Site

There are features and data related to the site that need to be recorded in this section. General site features and information may include:

• Beneficial information related to the previous application of site can be obtained from historical records and such information needs to be explained.
• General configuration and surface feature of the site. For instance, old buildings, mine shafts, quarries, filled areas, watercourses, roads, tracks, hedges, and trees should be recoded.
• If the site experienced erosion, earthquakes, and slope instability, it should be clearly and thoroughly described in addition to record cracks of surrounding building due to settlements.

General Geology of the Area

In this part of the engineering report, the following information should be provided:

• Provide notes with regard to geology of the site
• Compare available information, which may be in form of memoir and maps, to the information obtained from boreholes.
• If there are any faults, mines, springs, swallow holes, quarries, and other features at the project site, then they should be taken into consideration if they influence in the foundation work.

Description of the soil conditions found in boreholes and trial pits The following information should be provided in this section:

• It is required to provide general description (not detailed description) of soil site which should include changes in levels of different strata, ground water table, and ground configuration.
• if several boreholes have been taken, then it is a good strategy to draw number of these through the section of the site.
• This is to show configuration and level variation of the strata that is crucial to the engineering problem.

Nonetheless, these diagrams should not include detailed information of soil profile for instance changed in ground water table in successive strata because such information could lead to costly error.

Laboratory Test Results

This part of the engineering report should include the following information:

• Short description about types of tests which are carried out.
• Refer to any uncommon test result
• Detailed test results should not be provided in this section and they should be given in appendices.
• If non-standard test procedure is utilized for any particular test, then the test procedure should be explained.

Discussion of results of investigation in relation to the foundation design and construction

This part by far the most significant components of the engineering repot for foundation design and construction. The discussion should be clear and concise and efforts should be made to prevent the use of words such as (but) and (if). It is recommended to divide this section into differ parts so as to make it more clear, readable, and understandable. The subheadings of the discussion includes

• Introduction: in this part of discussion description of the main structure and related imposed loadings should be provided
• General ground condition assessment
• Foundation type that could be used.
• Another subheading is special structures if present such as electricity generation station and turbine house. These structures usually require special foundations.
• The last part of the discussion is about the design Method.

Note: In the discussion, the discussion about inappropriate foundations should be avoided since it would be waste of time. The discussion should clearly state type and depth of foundation, allowable bearing pressure, and anticipated settlement due to allowable pressure. Moreover, the benefit of adopting deeper foundation to allow for higher bearing pressure or decreasing foundation settlement. Furthermore, if the pile foundation is adopted, then the engineering report should state bearing strata, to which the pile is driven, pile penetration likelihood into the strata, working load magnitude per pile, Finally, the pile installation difficulty and any possible influence on the surrounding structure should be specified.

Recommendations

The facts that have been achieved in the report should be used as base for the foundation design recommendation. It is advised that, the head of investigation and the design have good communication throughout the entire stages of the work.

Conclusion

Typically the following points should be provided in conclusion:

• The major points of discussion will be summarized in this section provided that the discussion is lengthy.
• Findings which are drawn from the investigation will be provided as well.