K₀ CONSOLIDATION CHARACTERISTICS OF MALAN LOESS IN JINZHONG AREA

The static lateral pressure coefficient,K₀,describes the in-situ stress state of soils and is an important parameter in engineering calculations. In this paper,K₀ consolidation test at constant strain rate is conducted on the Malan loess at different water contents to investigate the variation of K₀. Both intact and remoulded specimens are employed and tested. It is found that:(1)K₀ of Malan loess is not a constant value. According to the structural evolution during the test,the consolidation process can be divided into pre-collapse and post-collapse stages. K₀ of the pre-collapse stage(K_0i)increases linearly with increase in water content,while that of the post-collapse stage(K_0s)follows a hyperbolic growth pattern with increase in water content. In addition,K_0s is always greater than K_0i. (2)The K_0i from the intact specimens is less than that of the remoulded ones. The intact Malan loess has a strong vertical structure,which weakens the development of horizontal stress. The remoulded Malan loess is homogeneous and isotropic,resulting in a higher K_0i. (3)In the post-collapse stage,the original structure of the intact specimens is destroyed,resulting in a structure similar to that of the remoulded specimens. This makes comparable K_0s values for both intact and remoulded Malan loess. (4)Compared with other soils,K_0s of Malan loess always show a lower value(K_0s of saturated intact Malan loess is about 0.45,while that of other soils can be as high as 0.8). Numerical simulation of slopes under different K₀ values shows that soil with low K₀ is more susceptible to the formation of deep vertical tensile cracks. This to some extent explains the formation of typical macroscopic landform,such as loess wall and loess column.