Study on the Dynamic Characteristics of Loess

Abstract

Due to its special material composition, formation environment, and special structure, loess usually shows different engineering and dynamic characteristics from ordinary soil. Based on previous research results, this paper studies the Haiyuan loess. It is found that: (1) the variation coefficients of various physical properties (except for the liquid index) of loess in the region are relatively stable, but the mechanical properties are relatively discrete; (2) the correlation among natural water content, void ratio, and density is high, but the correlation between mechanical properties is poor; (3) the consolidation ratio, effective confining pressure, and dynamic shear modulus ratio change in direct proportion, while the damping ratio changes in the opposite direction with increasing shear strain; and (4) in this paper, the recommended model of shear wave velocity and burial depth of loess in the study area is given. Compared with the example, the error is smaller and more reliable. (5) The characteristic period of the seismic response spectrum of the loess soil layer is not sensitive to the change in the damping ratio, and the change amplitude is small.

A resistivity-based experimental compaction model for Yunnan laterite

“…where is the composite index of resistivity structural properties, is the porosity, and p and q are the fitting parameters. As discussed above, the functional relationships between the comprehensive index of resistivity and resistivity structure characteristics, compactness, and saturation and porosity are shown in Equations ( 13), (14), and (15), respectively. To improve the curve-fitting accuracy, the comprehensive index of resistivity structure characteristics was taken as the absolute value, and the characteristic parameters of each equation were included in the set, the characteristic parameters that were not directly related to each required parameter were removed, and the simplified equations, using the recursive fusion analysis method [33][34] , the rest parameters were multiplied to give the functional relationship = , R 2 =0.886, and the fitting accuracy was relatively sufficient.…”

“…Soil resistivity mainly depends on the porosity, pore water, solid particle composition, and cementation state, and the concepts of structural factor, resistivity index, and apparent resistivity structure factor of the rock and soil media have been proposed through resistivity logging by some scholars in the early stage [7][8][9][10] . In recent years, with the development of resistivity theory, the structural characteristic parameters of resistivity have been gradually applied to the study of the microstructure, hydromechanical, and structural properties of various soils [11][12][13] , especially the evaluation analysis of special physical and mechanical properties of regional soils 14,15 . The resistivity method has shown to be an effective tool for studying the structural properties of soil with the advantages of fast and nondestructive testing.…”

“…Resistivity models for unsaturated sands were developed for different degrees of contamination 8,19 , and the resistivity model for unsaturated clay, as well as a prediction model for heavy-metal contaminated clay, have been established 9,20 . Subsequently, some scholars have proposed unsaturated loess resistivity models with different water and NaCl contents as variables 21,22 , along with the resistivity models of unsaturated and saturated expansive soils 15,23 . In recent years, resistivity models have been discussed for cohesive soil 24 , loess 25 , frozen soil 26,27 , cement soil 28,29 , and saline soil 30 .…”