Last November 2015, GEOINTEC has conducted a factual report & geotechnical site investigation and assessment report for a photovoltaic solar plant in Gunma Prefecture, Japan.
Gunma Prefecture is located in the central area of the island in a mountainous region, where they are important slopes in the study area and unconsolidated sediments of volcanic origin. Considering these geographical and geological characteristics, the geotechnical survey has included in situ shear strength (Vane Test), dynamic penetration tests with Variable Energy (focusing on soils with low compactness and low consistency).
The geotechnical study aims to determine the nature and properties of soil aspects necessary to design the structure, surface improvements and the type of foundation, considering the following objectives:
- Identify constraints and geotechnical problems of the site under study.
- Study of natural hazards. Identify and define the geological risks and assets geomorphological processes that may affect the new project. Geomorphological mapping include the following: escarpments or unstable areas, drainage channels, alluvial fans, processes of rapid erosion or deposition, dissolution or subsurface forms acarcavamiento, endorreicas surface areas with accumulation of salts: sabkkhas, salt and salt crusts, discharges due to human activity, rocky outcrops and evaluation of the effects of weathering processes, presence of unstable soils or very low bearing capacity).
- Provide knowledge of geotechnical characteristics of the land, according to the project structure.
- Existing zoning different lithologies in order to define the most appropriate foundations in each project area.
- Determine the geotechnical parameters of each lithology detected for project design, where different solutions according to the foundation load stresses are discussed.
- Recommendations for foundations of structures. Findings in relation to the overall stability of the foundation bearing capacity against the sinking, boot, horizontal ground failure, and structural failure.
- Determine levels of corrosion and aggressiveness of the land to the maximum depth of execution of foundations.
- Determine de levels of electrical resistivity of the terrain for the dimensioning and installation of the electrical facilities.