干湿循环后膨胀土力学特性的真三轴试验研究

doi:10.13722/j.cnki.jrme.2020.0902

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Abstract A series of drying-wetting tests，constant suction isotropic consolidation tests and constant suction true triaxial shear tests were carried out on intact expansive soils subjected to different drying and wetting cycles to investigate the mechanical properties of intact expansive by using unsaturated true triaxial apparatus. The effects of drying and wetting cycles on the soil-water curves，expansion and contraction characteristics，compression characteristics and strength characteristics were studied. The results show that as the number of drying and wetting cycles increases，the hysteresis loop of the drying curve and the wetting curve is smaller and smaller，even reverse hysteresis，but the drying rate and the wetting rate increase. The volumetric strains in the process of drying and wetting show obvious yield characteristics，which verifies the existence of the SI and SD yield envelopes in the expansive soil constitutive model. The drying yield suction is larger than the wetting yield suction，and both of them decrease with increasing the number of cycles. Drying and wetting cycles have a great influence on the compression characteristics under low confining pressure and low suction while have little effect on the compression characteristics under high confining pressure and high suction. The cohesion and the internal friction angle of expansive soils will be reduced by drying and wetting cycles. After drying and wetting cycles, the cohesion of expansive soils increases with increasing the suction and the intermediate principal stress，but the internal friction angle decreases with increasing the intermediate principal stress. In the range of low suction (s≤200 kPa)，the suction friction angle jb of expansive soils after drying and wetting cycles is a variable. After three drying and wetting cycles，the strength of expansive soils tends to be stable，and the suction friction angle increasing nonlinearly with b value can be regarded as a constant.

Key words： soil mechanics expansive soil true triaxial apparatus for unsaturated soil expansion and contraction drying and wetting cycle

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	Articles by authors
	FANG Jinjin1
	YANG Xiaolin1
	FENG Yixin2
	GONG Jian1
	NIU Haicheng1

Cite this article:

FANG Jinjin1,YANG Xiaolin1,FENG Yixin2, et al. True triaxial experimental study on mechanical properties of expansive soils after drying and wetting cycles[J]. , 2021, 40(5): 1043-1055.

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https://rockmech.whrsm.ac.cn/EN/10.13722/j.cnki.jrme.2020.0902 OR https://rockmech.whrsm.ac.cn/EN/Y2021/V40/I5/1043

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