The Subsoil Characterization of Matarbari Ultra Super Critical Coal-Fired Power Project, Bangladesh

Abstract

In this research, the subsoil characteristics and geotechnical issues have been evaluated for ground improvement, land development and design facilitation of Matarbari Ultra Super Critical Coal-Fired Power Project, Bangladesh. The subsoil conditions and geotechnical issues are addressed by determining the geotechnical parameters of soil. The soil characteristics are obtained from soil investigation and executed under land development for the procurement of power plant facilities. The American Society for Testing and Materials (ASTM International) standard is used to estimate all the soil parameters in field and laboratory tests. The measured soil properties establish the area consists mainly of two types of soils, i.e., Cohesive Clayey and non-cohesive Sandy soils. The cohesive soils are mostly composed of gray to dark gray CLAY, CLAY with Sand, SILT with Sand, and Sandy CLAY with fine to mediumgrained Sand. The upper cohesive soil layer (Ac-1) is very soft to soft, normal to slightly consolidated with low undrained cohesion. This layer is expected to have a high potential for differential settlement because of the proposed design load. The lower cohesive soils (Ac-2 and Ac-3) are firm to very stiff and moderately over consolidated. These soils have moderate to high shear strengths with low compressibility relating to the expected range of the design loads. The non-cohesive Sandy soils consist of dark gray to gray SAND, SAND with Silt, Silty SAND, and Clayey SAND. The Sandy soils are poorly graded and loose to very loose at the upper part (As-1) and medium dense to dense in lower parts (As-2 & As-3) that expect less immediate settlement when a load placed on that. Geotechnical site conditions are challenging and deplorable. The soft soil layer Ac-1 (with As-1) complicates the design, especially in terms of foundation soil instability and settlement for certain structure types. Ground improvement techniques such as prefabricated vertical drain (PVD) and deep mixing method (DMM) can be applied to mitigate these challenges and for the improvement of the soft ground of the project area.