The SHARP - Soil Heterogeneity for soil Amelioration in Road Projects experiment proposes a novel approach to subgrade improvement: the strategic placement of gravel or other recycled aggregates in a layered configuration. This methodology aims to achieve a sufficient enhancement of the subgrade's mechanical properties, potentially eliminating the need for more resource-intensive and environmentally impactful techniques. The current research phase focuses on the evaluation of performance improvement in silt through the introduction of gravel layers via large-scale triaxial testing. Numerical simulations have already yielded promising results, highlighting the potential of this approach. However, the inherent size disparity between gravel and silt particles necessitates the use of large-scale testing equipment to accurately capture their composite behavior and avoid scale issues. Conventional triaxial equipment, typically limited to 10 cm diameter specimens, is inadequate for this purpose. The utilization of a large-scale triaxial apparatus facilitates the acquisition of reliable data directly applicable to real-world road and railway construction practices. The traditional Terzaghi method for analyzing consolidation (settling) in soils is not accurate for layered soils with different compressibility characteristics. This is a well-established fact (Schiffman & Stein, 1970; Lee et al., 1992). Previous research (Huang & Griffiths, 2010) has also shown that using the Terzaghi method for layered soils in finite element modeling can lead to inaccurate results due to issues with flow continuity at the interfaces between layers. This highlights the importance of studying consolidation in layered soils, both for practical reasons (ensuring the proposed solution is viable) and to gain a deeper theoretical understanding (the heterogeneity effect on consolidating silty soil). While numerical simulations have suggested that adding gravel layers to silty soil can significantly improve slope stability (Bossi et al., 2016), this needs experimental validation. Smaller lab specimens are not suitable due to the size difference between gravel and silt. The test performed within the SHARP project aimed to investigate the effectiveness of a "patchy" gravel-in-silt mix on volumetric changes and shear strength. This approach aims to be practical for construction crews by allowing the gravel to be spread in lenses within the existing subgrade. This would simplify construction and ensure a minimum level of performance for the improved subgrade. Ultimately, the goal is to use the data from these tests to assess the validity of using an "average friction angle" approach (Elkateb, 2003) for layered soils, considering the impact of the spatial distribution of the gravel layers. Numerical modeling can help answer these questions, but data for validation are necessary.
GEOLAB - Transnational Access project SHARP - Soil Heterogeneity for soil Amelioration in Road Projects
Beber, Raniero;
2024-01-01
Abstract
The SHARP - Soil Heterogeneity for soil Amelioration in Road Projects experiment proposes a novel approach to subgrade improvement: the strategic placement of gravel or other recycled aggregates in a layered configuration. This methodology aims to achieve a sufficient enhancement of the subgrade's mechanical properties, potentially eliminating the need for more resource-intensive and environmentally impactful techniques. The current research phase focuses on the evaluation of performance improvement in silt through the introduction of gravel layers via large-scale triaxial testing. Numerical simulations have already yielded promising results, highlighting the potential of this approach. However, the inherent size disparity between gravel and silt particles necessitates the use of large-scale testing equipment to accurately capture their composite behavior and avoid scale issues. Conventional triaxial equipment, typically limited to 10 cm diameter specimens, is inadequate for this purpose. The utilization of a large-scale triaxial apparatus facilitates the acquisition of reliable data directly applicable to real-world road and railway construction practices. The traditional Terzaghi method for analyzing consolidation (settling) in soils is not accurate for layered soils with different compressibility characteristics. This is a well-established fact (Schiffman & Stein, 1970; Lee et al., 1992). Previous research (Huang & Griffiths, 2010) has also shown that using the Terzaghi method for layered soils in finite element modeling can lead to inaccurate results due to issues with flow continuity at the interfaces between layers. This highlights the importance of studying consolidation in layered soils, both for practical reasons (ensuring the proposed solution is viable) and to gain a deeper theoretical understanding (the heterogeneity effect on consolidating silty soil). While numerical simulations have suggested that adding gravel layers to silty soil can significantly improve slope stability (Bossi et al., 2016), this needs experimental validation. Smaller lab specimens are not suitable due to the size difference between gravel and silt. The test performed within the SHARP project aimed to investigate the effectiveness of a "patchy" gravel-in-silt mix on volumetric changes and shear strength. This approach aims to be practical for construction crews by allowing the gravel to be spread in lenses within the existing subgrade. This would simplify construction and ensure a minimum level of performance for the improved subgrade. Ultimately, the goal is to use the data from these tests to assess the validity of using an "average friction angle" approach (Elkateb, 2003) for layered soils, considering the impact of the spatial distribution of the gravel layers. Numerical modeling can help answer these questions, but data for validation are necessary.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
