Evolution Characteristics of Cracks in Compacted Loess under Drying-Wetting Cycles

doi:10.11988/ckyyb.20230394

Abstract

Abstract:

To investigate the evolution of fractures in compacted loess under drying-wetting cycles, we conducted crack tests by varying the dry density and drying-wetting path using a self-developed device, and captured the surface crack patterns of soil samples.Furthermore, we quantitatively analyzed the soil cracks using PCAS software for morphological parameters and obtained strain fields via DIC (Digital Image Correlation) method. Our findings revealed three distinct stages in the development of compacted loess cracks with increasing drying-wetting cycles: initial slow growth, subsequent rapid expansion, and stabilization. Crack development intensity was influenced by both dry density and drying-wetting cycle paths. Higher dry densities hindered crack propagation, while larger amplitude of drying-wetting and lower moisture thresholds cultivated crack development. Additionally, the first principal strain along the crack’s central line exhibited a linear decrease with distance from the crack initiation point, indicating diminishing soil compression effects near the crack tip and adjacent blocks. These results provide insights into understanding crack evolution in compacted loess.

Key words: compacted loess, drying-wetting cycles, crack propagation, DIC, strain field

CLC Number:

TU43土力学

HU Chang-ming, HU Ting-ting, ZHU Wu-wei, YUAN Yi-li, YANG Xiao, LIU Ming-liang, HOU Xu-hui. Evolution Characteristics of Cracks in Compacted Loess under Drying-Wetting Cycles[J]. Journal of Changjiang River Scientific Research Institute, 2024, 41(8): 96-103.

Figures/Tables 17

Table 1 Physical parameters of the compacted loess

相对密度	液限/ %	塑限/ %	塑性指数	颗粒组成/%
相对密度	液限/ %	塑限/ %	塑性指数	>0.075 mm	0.075~ 0.005 mm	<0.005 mm
2.70	29.7	18.4	11.3	1.05	78.43	20.52

Fig.1 Diagram of test apparatus

Fig.2 Diagram of PCAS system processing

Fig.3 Surface crack patterns after different drying-wetting cycles

Fig.4 Crack indices after different drying-wetting cycles

Fig.5 Distribution of surface cracks of samples with different dry densities

Fig.6 Crack indices of samples with different dry densities

Fig.7 Distribution of surface cracks under different drying-wetting paths

Fig.8 Crack indices under different drying-wetting paths

Fig.9 Distribution of the first principal strain field on soil sample surface during the first drying process

Fig.10 Distribution of the first principal strain field of soil samples after different drying-wetting cycles

Fig.11 Variation curves of the first principal strain at different soil positions

Fig.12 Relationship between principal strain along the crack’s central line and distance from the crack initiation point

Fig.13 The first principal strain field of soil samples with different dry densities

Fig.14 Strain curves of parts of the soil samples with different dry densities

Fig.15 The first principal strain field of soil samples under different cycle paths

Fig.16 Variation curves of the first principal strain at parts of the soil samples under different cycle paths

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