地质科技通报 (Nov 2022)
Experimental study on the permeability characteristics and structure damage of Malan loess in Heifangtai area
Abstract
Continuous water diversion irrigation has changed the structure of Malan loess, led to the reduction of the shear strength of the soil, and thus the frequent occurrence of landslides in the Heifangtai area, which seriously affected the lives and property safety of local residents. In order to analyze the infiltration process of Malan loess, nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) tests were respectively carried out to investigate the permeability and structural damage microscopic characteristics for loess at different initial water contents and different dry densities. The obtained results show that the infiltration rate is negatively correlated with the initial moisture content of the soil. The density is negatively correlated, and it will take the lead to a higher water content area. The water content is higher, the increase in the proportion of micropores is smaller, and the less obvious the change in the contact mode between particles; the dry density of the sample is larger, the different pore volumes basically change in the same amount, the contact area is significantly reduced, and more overhead pores are formed, which are connected to each other, leading to good water storage capacity. After infiltration, the original dense structure of the sample is lost, and the particles are severely broken. Some slender particles evolve into nearly round particles or elliptical particles, and the contact mode between particles becomes point-edge contact.The intergranular cementation is damaged and destroyed, and even some particles in the aggregates are separated and fall off, resulting in the loss of soil strength and eventually leading to landslides. The results can provide a basis for the prevention and control of loess landslides.
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