The importance of engineering and geological mapping in slope protection
Engineering and geological mapping is a fundamental step in planning and executing slope protection works. This process involves the detailed collection, analysis and interpretation of data on the geological and geotechnical characteristics of the terrain. It enables engineers to identify potential risks and develop effective strategies for stabilizing and protecting slopes during and after construction works.
The first step in engineering and geological mapping is the collection of data on the geological composition of the terrain. The detailed analysis of information such as geological structure, hydrogeological conditions and similar factors allows engineers to assess the mechanical properties of the rock and soil, as well as the presence of potentially unstable zones. This data is crucial for planning the works, as it enables the assessment of risks and the determination of necessary measures for slope protection.
However, engineering and geological mapping is not always feasible or straightforward, especially when dealing with excavations for open pits the structure of which is assessed using other geotechnical investigation and testing methods, such as geophysical methods or exploratory drilling. Such investigative works often result in excavation conditions that are either more favorable or less favorable than anticipated. The actual state of the material in which the excavation is carried out cannot be known with certainty until the work begins.
The protection of excavations is often based on the data obtained from these investigative methods. For example, geophysical methods provide insights into the layering of materials, while exploratory drilling offers a more detailed understanding of the mechanical properties of these materials. Based on this data, engineers can design adequate protection systems to ensure the stability of the excavation and the safety of the works. However, there is always a certain level of uncertainty that requires adjustments of the plans during the actual execution of the works, depending on the real conditions on the ground.
During the execution of works, engineering and geological mapping allows for continuous monitoring and adjustment of the planned protection measures. Regular geotechnical testing and monitoring help detect any changes in slope stability and enable timely interventions. For example, if unexpected changes in geological conditions are observed during the works, engineers can adjust the design of support structures or introduce additional measures to stabilize the slope or excavation.
A practical example is a project for protecting an open pit for an auxiliary building. During project development, based on available investigative works, the protection of the pit face was planned using shotcrete and anchors, or supportive and polypropylene mesh combined with anchors in the most critical zones. In the zones for which this type of protection was planned, a higher percentage of soil material compared to rock was expected.
However, at the start of the excavation works for the open pit, a geotechnical survey revealed that the geotechnical profile of the larger part of the site was more favorable than what was predicted by the project documentation. Based on these new findings, the proposed protection solution for the open pit was adapted.
Specifically, the length of the anchors was reduced from 9.0 m to 6.0 m and 4.5 m, while in some zones, anchors were not necessary at all. Instead, the pit face was protected solely with a protective mesh, which was deemed adequate given the more favorable geotechnical profile. This adaptation, thanks to the geotechnical survey and the engineering and geological mapping following the excavation, not only ensured the stability of the open pit but also optimized the costs and time required for the works.
In conclusion, engineering and geological mapping is a key element in the process of planning and executing slope and excavation protection works. It provides a detailed understanding of geological and geotechnical conditions, identifies potential risks and helps develop effective measures for stabilizing and protecting slopes. Through precise data collection and analysis, engineers can predict slope behavior and implement measures that ensure the safety of persons and infrastructure, as well as the preservation of the environment. Therefore, engineering and geological mapping forms the basis for the successful execution of works and the long-term stability of geotechnical structures.
Read more: Geotechnical investigation and testing
