Abstract
The application of tunnel-slag-improved high liquid limit soil as filling materials in subgrade is a green environmental technology. This study explored the influence of tunnel slag mixing on the physical and mechanical properties of improved soils, based on the engineering background of Liyu highway, Guangxi Province, China. Firstly, the optimal moisture content, maximum dry density, shear strength parameters, California bearing ratio (CBR) and resilience modulus of plain and tunnel-slag-improved high liquid limit soils were experimentally determined. Results showed that the direct utilization of untreated soil was unacceptable in subgrade practice. A significant enhancement of integrity of high liquid limit soils could be obtained by tunnel slag mixing, and the value of 15% was determined as the optimal tunnel slag content in soils, leading to improved soil performance meeting the specification requirements. Then, numerical simulation on the stability of subgrade slope of tunnel-slag-improved soils at the content of 15% was conducted. It also reported the long-term subgrade settlements. The feasibility of utilization of tunnel slag in improving properties of high liquid limit soils was further validated. Finally, a good application of tunnel-slag-improved high liquid limit soil as subgrade filling materials in Liyu highway was achieved. The findings in this study could provide useful guidance for similar engineering.
Highlights
It is infeasible to have a direct use of these soft soils in geotechnical practice because of their high moisture content and low bearing capacity [2–5]
Tunnel slag shows features similar to those of construction and demolition wastes, and it is considered to be acceptable to use the tunnel slag in the high liquid limit soil. This green environmental technology can both address the problem of disposal of tunnel slag and provide subgrade filling materials with higher performance, and it has been increasingly promoted in highway subgrade practice
In order to further validate the feasibility of tunnel-slag-improved high liquid limit soils in subgrade in Liyu highway, numerical simulation focusing on the stability of subgrade slope and long-term settlements of subgrade was conducted
Summary
Soft soil deposits are prevalent in coastal areas, deltas and floodplains throughout the world [1]. The utilization of untreated soft soils as the filling materials may make it difficult to achieve the optimal moisture and required compaction degree after rolling, leading to a low bearing capacity, excessive settlement and possible slope instability under the traffic loadings. Tunnel slag shows features similar to those of construction and demolition wastes, and it is considered to be acceptable to use the tunnel slag in the high liquid limit soil This green environmental technology can both address the problem of disposal of tunnel slag and provide subgrade filling materials with higher performance, and it has been increasingly promoted in highway subgrade practice. Based on the engineering background of Liyu highway, Guangxi Province, China, this study discussed the feasibility of utilization of tunnel-slag-improved high liquid limit soils in subgrade. An attempt was made to apply tunnel-slag-improved high liquid limit soils in the subgrade practice of Liyu highway
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