How do you choose the best geotechnical investigation method for your site?

1 Types of geotechnical investigation methods

There are two main types of geotechnical investigation methods: intrusive and non-intrusive. Intrusive methods involve drilling, sampling, or testing the soil or rock directly, using equipment such as boreholes, cones, probes, or test pits. Non-intrusive methods use remote sensing techniques, such as seismic, electrical, magnetic, or radar, to measure the properties of the subsurface without disturbing it. Both types of methods have advantages and disadvantages, depending on the accuracy, reliability, cost, and environmental impact of the data they provide.

2 Factors to consider when choosing a geotechnical investigation method

When selecting a geotechnical investigation method, there are several factors to consider, such as the purpose and scope of the project, the site characteristics and constraints, and the budget and time available. The level and type of data required for a project depend on its geotechnical needs and risks - for instance, a high-rise building may require more detailed information than a low-rise structure. Additionally, the physical and geological features of the site can determine the feasibility and suitability of different methods - for example, a rocky site could necessitate more drilling than a sandy site. Furthermore, the cost and duration of the investigation are related to the complexity, quantity, quality of data needed, as well as the availability and efficiency of equipment and personnel - a non-intrusive method may be faster and cheaper than an intrusive one, but may also be less accurate.

3 How to select a geotechnical investigation method

When selecting a geotechnical investigation method, it is important to consider the benefits and drawbacks of each option, as well as the alternatives. Generally speaking, the process should start with defining the project objectives and geotechnical parameters of interest. It is then necessary to review available site information and preliminary data, such as maps, reports, surveys, or investigations. Next, identify potential methods that can address the project objectives and parameters, which may include a combination of intrusive and non-intrusive methods. Evaluate each method's accuracy, reliability, cost, time, safety, and environmental impact before choosing the best option that meets the project needs and constraints. This decision may require a cost-benefit analysis or a risk assessment.

4 How to conduct a geotechnical investigation

Choosing the geotechnical investigation method or methods is the first step in planning and executing the investigation. This process includes preparing a geotechnical investigation plan that outlines the objectives, scope, methods, equipment, personnel, schedule, budget, quality control, and reporting of the investigation. Additionally, you must obtain the necessary permits and approvals for the site and investigation activities. Mobilizing equipment and personnel to the site is necessary to perform fieldwork according to the plan. This may include drilling, sampling, testing, or measuring soil or rock using selected methods. Collecting and recording data from fieldwork is essential along with transporting samples to the laboratory for further testing or analysis if needed. Analyzing and interpreting data using appropriate methods and software is also important in order to compare them with design criteria and standards. Finally, a geotechnical investigation report summarizing findings, conclusions, and recommendations of the investigation should be prepared.

5 How to use the geotechnical investigation results

The final step is to use the geotechnical investigation results to inform the design and construction of the project. This includes communicating the results to the relevant stakeholders, incorporating them into the geotechnical design and analysis, addressing any issues or challenges identified by the investigation, and monitoring and verifying the performance of the project during and after construction. This will ensure that any geotechnical issues are addressed properly, and that the project is built in accordance with the investigation results.