Measurement and Uniform Formulation of Soil-Water Characteristic Curve for Compacted Loess Soil with Different Dry Densities

Yu Wang,Ping Li,David D Lawrence,Tonglu Li,Yulu Lei,Jian Xu

doi:10.1155/2021/6689680

Abstract

To investigate the effect of dry density on the soil-water characteristics of compacted soil, loess used as filling in the land-making project of the Yan’an new district was collected and compacted to five initial dry densities of 1.40, 1.50, 1.60, 1.70, and 1.80 g/cm3, respectively. The soil-water characteristic curves (SWCCs) of all specimens in the range of 0–105 kPa were measured using the filter paper method. The measured data were fitted using the Fredlund and Xing equation for each initial dry density. The SWCCs have obvious differences in a suction range below 100 kPa and overlap when the suction range is higher. This suggests that the SWCC of compacted soil is independent of the initial dry density in the high suction range, but the correlation with the initial dry density exists in the low suction range. Therefore, the correlation functions of the parameters in the Fredlund and Xing equation with respect to the initial dry density were regressed, respectively. By substituting these functions into the Fredlund and Xing equation, the state surface function of θ w − ψ − ρ d was obtained and can reflect the SWCCs of all densities of the filled soil to support the further investigation of the unsaturated behavior of compacted soil.

Highlights

In the Chinese loess plateau, loess formations are used as natural foundation materials for buildings and infrastructures and as compacted geomaterials for building foundations
Once the specimens were remolded, they were put into sealed desiccators to maintain the original water content and keep free from disturbances. e specimens for each initial dry density were set as a group and used to measure the soil-water characteristic curves (SWCCs). e measuring processes were carried out as follows: (1) Filter paper preparation: ordinary filter paper was cut to the same size as the specimen surface with a diameter of 61.8 mm, as shown in Figure 4(a), and used to cover the surface of the specimens to protect them against falling slags and to protect the test filter paper against contamination. e test filter paper was slightly smaller than the specimen or ordinary filter paper and had a diameter of 42.5 mm
Summary and Conclusion is study measured the SWCCs of compacted loess soil with different density using the filter paper method (FPM), and a unified function based on the Fredlund and Xing equation was regressed

Summary

Introduction

In the Chinese loess plateau, loess formations are used as natural foundation materials for buildings and infrastructures and as compacted geomaterials for building foundations. This study focused on the measurement and uniformity of the SWCCs obtained for compacted loess soil with different dry densities. E data measured for each specimen with different compacted density were fitted using the Fredlund and Xing equation [16] to obtain the respective SWCCs, and the SWCCs of the compacted loess were unified as a binary function of the matric suction against the water content and dry density, which can be used to investigate geotechnical problems related to compacted loess throughout the entire density and water content range. According to the laboratory test data for 19 boreholes in the filled soil (Figure 2), the dry density of the compacted loess samples is mostly in the range of 1.40–1.80 g/cm and accounts for 97% of the total density. Specimen number Initial dry density (g/cm3) Initial void ratio Degree of compaction (%) Same parameters Value

94 Liquid limit

Regression for SWCCs with Measured Data

Findings

Unified SWCC of Compacted Loess