炎热多雨气候下花岗岩残积土的强度衰减与微结构损伤规律

doi:10.13722/j.cnki.jrme.2020.0073

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Abstract The triaxial consolidation undrained(CU) shear tests and magnetic resonance imaging(MRI) scans were conducted on undisturbed samples of granite residual soils under multiple dry-wet cycles，and the stress-strain curves，shear strength parameters and pore volume content were obtained to evaluate the damage effect of hot and rainy weather on the soil. The experimental results show that，after 0–2 dry-wet cycles，the stress-strain curves of the samples present strain softening and weak strain hardening behaviors under low and high confining pressures，respectively. However，the stress-strain curves of the samples after 3–8 cycles all present weak strain hardening behavior. With increasing the dry-wet cycle number，the effective cohesion and effective internal friction angle gradually decrease，while the attenuation amplitude of the effective cohesion is more obvious. Based on the surface relaxation coefficient of granite residual soils，the pore-volume distribution curves were acquired from the T2 distribution curves，and subsequently，the pores were divided into micropores and cracks according to the pore diameter. It is also revealed that，with increasing the dry-wet cycle number，the content of the micropores declines slightly while the content of the cracks increases significantly. The pore volume content and the effective strength index show a negatively correlated linear relationship，indicating that the decaying patterns in mechanical properties are synchronized with the evolution laws of the pore structure. The damaged effects of dry-wet cycles on granite residual soils are caused by the increase of the matrix suction during dehumidification，the expansive force and the loss of cements during moisture absorption.

Key words： soil mechanics granite residual soil drying-wetting cycle triaxial shear tests magnatic resonance imaging strength index pore structure

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	AN Ran1
	2
	KONG Lingwei1
	2
	LI Chengsheng1
	2
	LUO Xiaoqian1
	2

Cite this article:

AN Ran1,2,KONG Lingwei1, et al. Strength attenuation and microstructure damage of granite residual soils under hot and rainy weather#br#[J]. , 2020, 39(9): 1902-1911.

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https://rockmech.whrsm.ac.cn/EN/10.13722/j.cnki.jrme.2020.0073 OR https://rockmech.whrsm.ac.cn/EN/Y2020/V39/I9/1902

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