Experimental Study on the Permeability of Compacted Loess
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EXPERIMENTAL INVESTIGATIONS EXPERIMENTAL STUDY ON THE PERMEABILITY OF COMPACTED LOESS
UDC 624.131.37:624.131.23 Y. Guo, W. Ni,* Z. Kou , Y. Zhao, and Y. Nie School of Geology Engineering and Geomatics, Chang'an University, Xi'an, China *Corresponding author Email: [email protected].
In the western regions of China, loess soils are widely used as fill materials in the construction of highways and building foundations. The hydraulic conductivity of this fill material is a significant parameter for initial engineering designs, but currently there are a very limited number of investigations into this aspect. In this study, a series of tests on compacted loess soils was conducted to determine how the dry density and water content affect loess permeability. The test results show that the hydraulic conductivity decreases gradually with the final water content or with increase in the final dry density. The phenomenon is induced by a decrease in cumulative volume or void ratio, which is verified by the results of mercury intrusion porosimetry and scanning electron microscopy images. A new mathematical model is proposed for predicting the value of k in compacted loess soils, expressed as a function of water content and void ratio.
1. Introduction Loess soils are widely distributed in many countries, including China, Russia, the United Kingdom, France, Germany, and New Zealand. China has the most extensive loess deposits in the world, approximately 7% of the total territorial area of China [1]. In recent years, and in conjunction with the increase in infrastructural development, construction in western cities of China has taken place on areas underlain by loess soils. However, loess is sensitive to water content and is susceptible to collapse [2], and its physical properties can deteriorate significantly if it is subjected to high rainfall or groundwater migration. Such deterioration can cause serious engineering failures. Therefore, many researchers have investigated the basic properties of loess soils in recent years. Yu [3] and Fang et al. [4] defined the formation age, depositional mechanism, and material source of loess deposits in China. Ye et al. [5] and Liu et al. [6] analyzed the collapse potential of natural loess through laboratory tests. Based on the results, an evaluation method was established. Wang et al. [7] clarified the effect of dry density and initial water content on the permeability of natural loess, and those effects were verified by Chen et al. [8] through scanning electron microscopy (SEM). Hu et al. [9] and Chu and Shao [10] conducted a series of triaxial compression tests on natural loess. Through these results, some constitutive models were proposed which took soil structure, creep, and sampling disturbance into consideration. Despite abundant literature on loess soil, the focus has been primarily on natural loess. However, construction of highways and foundations in western China is done predominantly on loess soils introduced as fill material. This material is typically in an unsaturated and remo
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