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Volume change behavior of compacted loess under drying/wetting and freezing/thawing cycles
Abstract The long-term drying/wetting (D/W) and freezing/thawing (F/T) cycles damage the structure of the roadbed soil in loess areas, leading to a series of engineering geological disasters, such as roadbed collapse and cracking. In this study, a series of field monitoring was carried out on the Jihe Expressway, which was built on the Loess Plateau in China. It shows that drying/wetting (D/W) and freezing/thawing (F/T) cycles are important factors leading to periodic settlement and heave of loess roadbeds. A new temperature-controlled unsaturated soil triaxial apparatus was developed to explore the deformation mechanism of compacted loess under D/W and F/T cycles. The results of laboratory tests indicate that, in the isotropic stress state, both D/W and F/T cycles can reduce the void ratio and increase the volume deformation of compacted loess. In the D/W cycle, the soil samples show the collapse behavior, but the deformation of heavily over-consolidated samples is relatively less compared with lightly over-consolidated samples. On the other hand, repeated F/T cycles lead to fluctuating changes in the volume of compacted loess. Increasing the dry density can effectively reduce the deformation caused by F/T cycles. Moreover, the combination of the D/W and F/T cycles may further enhance the volume changes of the compacted loess. As the number of D/W and F/T cycles increases, the compressibility and irrecoverable deformation of the compacted loess increases, leading to a deterioration of its engineering properties.
Highlights The characteristics and causes of roadbed deformation in loess area were investigated by field monitoring. A new temperature-controlled unsaturated soil triaxial apparatus was developed. The mechanism of D/W and F/T cycles on the deformation of compacted loess was discussed. The coupling of D/W and F/T intensifies the volume changes of the compacted loess.
Volume change behavior of compacted loess under drying/wetting and freezing/thawing cycles
Abstract The long-term drying/wetting (D/W) and freezing/thawing (F/T) cycles damage the structure of the roadbed soil in loess areas, leading to a series of engineering geological disasters, such as roadbed collapse and cracking. In this study, a series of field monitoring was carried out on the Jihe Expressway, which was built on the Loess Plateau in China. It shows that drying/wetting (D/W) and freezing/thawing (F/T) cycles are important factors leading to periodic settlement and heave of loess roadbeds. A new temperature-controlled unsaturated soil triaxial apparatus was developed to explore the deformation mechanism of compacted loess under D/W and F/T cycles. The results of laboratory tests indicate that, in the isotropic stress state, both D/W and F/T cycles can reduce the void ratio and increase the volume deformation of compacted loess. In the D/W cycle, the soil samples show the collapse behavior, but the deformation of heavily over-consolidated samples is relatively less compared with lightly over-consolidated samples. On the other hand, repeated F/T cycles lead to fluctuating changes in the volume of compacted loess. Increasing the dry density can effectively reduce the deformation caused by F/T cycles. Moreover, the combination of the D/W and F/T cycles may further enhance the volume changes of the compacted loess. As the number of D/W and F/T cycles increases, the compressibility and irrecoverable deformation of the compacted loess increases, leading to a deterioration of its engineering properties.
Highlights The characteristics and causes of roadbed deformation in loess area were investigated by field monitoring. A new temperature-controlled unsaturated soil triaxial apparatus was developed. The mechanism of D/W and F/T cycles on the deformation of compacted loess was discussed. The coupling of D/W and F/T intensifies the volume changes of the compacted loess.
Volume change behavior of compacted loess under drying/wetting and freezing/thawing cycles
Cai, Guoqing (author) / Liu, Qianqian (author) / Li, Kunhong (author) / Zhang, Jun (author) / Liu, Yi (author) / Zhou, Annan (author)
Engineering Geology ; 326
2023-10-10
Article (Journal)
Electronic Resource
English
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