Slope Investigation
Slope investigations are undertaken for various reasons. Slope failures, either natural or human induced, have the capacity to cause destruction to lives, property and the environment in their radius. It is therefore essential that such investigations are adequately carried out to determine the geotechnical characteristics of the slope material and to determine the stability and current state of the slope.
The process of a slope investigation typically commences with initial fieldworks. During this stage, reconnaissance of the site is carried out. This is done to provide an understanding of the existing rock and soil conditions on the slope. Common surveying techniques involved in fieldworks include stratigraphic logs, structure logs, detailed mapping, block work measurement, soil sampling, inspections and geodynamic testing. These techniques help to determine the orientation, continuity and relative proportion of the rock masses and soils on the slope and the engineering properties of the materials present.
Following the initial fieldworks, the collected data is analyzed to determine the properties of the slope. This process starts with a review of the data collected during the reconnaissance. The data is then calibrated with respect to engineering design parameters and laboratory tests conducted on he samples collected during fieldworks. This is usually conducted through geotechnical and geophysical investigations.
Geophysical investigations are conducted to understand the physical structure of the slope. This allows for determination of various parameters such as the thickness of rock or soil structures, the permeability of these structures and the composition of the ground. These investigations include acoustic and seismic surveys, gravity surveys and Electric Resistivity Tomography surveys.
Geotechnical investigations are undertaken to understand the geological, geotechnical and geochemical properties of the slope. This includes depths to rockhead and groundwater, degree of weathering, bulk density and groundwater flow direction. This forms the basis of understanding the mechanical and hydraulic properties of the slope material, leading to the maturation of the slope recommendation.
Following the analysis phase, the evaluation of the slopes stability is undertaken. This involves the use of numerical modeling to be develop an understanding of the behaviour of the slope and the response to various loadings. Models may include analytical and finite element simulation using parameters determined from the data analysis. This can help determine the safety factor, angles of failure, pore pressure distribution and other factors that affect the stability of the slope.
The slope investigation concludes with the development of a report detailing the entire process of the investigation and the recommendations of the condition, maintenance and repair of the slope. The report is finalized with respect to the design requirements, engineering parameters and regulatory guidelines. The report and its recommendations are used as a tool to decision makers, allowing them to determine the best possible action to undertake with regards to the slope condition.
Slope investigations are important components of geotechnical engineering, allowing for the determination of the structure, stability and properties of the slope. Understanding the conditions of such slopes is important for decision makers to ensure safety, protect lives and environment and reduce risk throughout the life cycle of these structures.
