Mechanism and Experimental Study on Deterioration of Collapsible Loess Performance Induced by Irrigation

doi:10.12068/j.issn.1005-3026.2025.20240106

Abstract

Abstract:

In order to investigate the mechanism of performance deterioration in collapsible loess under the influence of irrigation， laboratory tests with varying irrigation and evaporation cycles under different salt mass fraction conditions were conducted. A deterioration model of remolded loess collapsibility affected by irrigation and evaporation cycles was established， along with proposed evaluation indices for deterioration performance. The microstructural evolution characteristics were obtained through scanning electron microscopy （SEM） tests. Results indicate that the collapsibilify coefficient exhibits defferent growth patterns with increasing irrigation and evaporation cycles and rising salt mass fraction. The coupled effects of irrigation and evaporation and salt erosion render the loess skeletal structure more porous and weaker， providing additional pore space for collapsibility. When the salt mass fraction is below 0.3%， the deterioration rate caused by irrigation and evaporation exceeds that from salt erosion. Conversely， when the salt mass fraction exceeds 0.6%， the deterioration rate from salt erosion surpasses that caused by irrigation and evaporation. This research can serve as a reference for hazard assessment and prediction of performance deterioration in collapsible loess within the Loess Plateau region.

Key words: remolded loess, salt erosion, irrigation and evaporation cycle, deterioration of collapsibility, soil structure

CLC Number:

TU 411

Shi-xiong MA, Shu-hong WANG, Zhi LIU. Mechanism and Experimental Study on Deterioration of Collapsible Loess Performance Induced by Irrigation[J]. Journal of Northeastern University(Natural Science), 2025, 46(11): 134-142.

Figures/Tables 12

Table 1 Physical properties of Q3 loess sample

自然密度

ρ₀/（g·cm^-3）

干密度

ρ_d/（g·cm^-3）

天然含水率

w₀/%

初始孔隙比

e₀

土粒相对密度

ρ_r

塑限

w_P/%

液限

w_L/%

Table 2 Initial soluble salt ion composition and mass fraction of Q3 loess sample

类型	Ca²⁺	Mg²⁺	Na⁺	K⁺	HCO $3 -$	SO $4 2 -$	Cl^-	CO $3 2 -$
质量分数	87.44	53.99	130.50	6.86	233.29	246.43	101.18	89.21

Table 2 Initial soluble salt ion composition and mass fraction of Q3 loess sample

类型	Ca²⁺	Mg²⁺	Na⁺	K⁺	HCO $3 -$	SO $4 2 -$	Cl^-	CO $3 2 -$
质量分数	87.44	53.99	130.50	6.86	233.29	246.43	101.18	89.21

Fig.1 Experimental study by irrigation and evaporation cycles of loess samples

Fig.2 Relationship between collapsibility coefficient δs and vertical stress p under different cycles

Fig.3 Relationship between collapsibility coefficient and irrigation and evaporation cycles at 200 kPa

Fig.4 Relationship between collapsibility coefficient and salt mass fraction at 200 kPa

Fig.5 SEM images of samples after different irrigation and evaporation cycles(ws=0)（a）—N=0；（b）—N=2；（c）—N=4；（d）—N=8.

Fig.6 SEM images of samples at different salt mass fractions(N=10)

Fig.7 Binarization and pore identification of SEM image

Fig.8 Pore area distribution of different loess samples

Fig.9 Relationship between collapsibility coefficient of loess samples at different salt mass fractions and irrigation and evaporation cycles at 200 kPa

Fig.10 Relationship between collapsibility deterioration rate and salt mass fraction

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