Peak Strength Of Soil Research Articles

Nonlinear Model of Soils Under Complex Stress Paths

The direction of stress has an obvious influence on the mechanical properties of soils under the static and dynamic conditions. This is mainly because that geomaterials are anisotropic in general. Mechanical analysis shows that the increment of stress can be divided into the coaxial component and the rotational component of which the coupling change of shear stress and normal stress in the physical space can be used to measure the direction of the principal stress. In light of the shear-normal stress ratio, a simple nonlinear model which can simulate the deformation behavior of soils under complex stress path is proposed. The stress–strain relationship of the model in the form of component is established considering the initial shear modulus and the peak strength of soil which are closely related to the anisotropy of soil and the direction of stress. Comparisons of predicted and measured results of tests under complex stress paths show that the newly build model can capture deformation characteristics of cohesive soil and granular materials reasonable wells.

Stress-deformation and compressibility responses of bio-mediated residual soils

Bio-mediated soil improvement technique has attracted increasing interest from geotechnical engineers in recent years. This paper investigates the stress-deformation and compressibility responses of bio-mediated soil at laboratory scale. A typical residual soil was subjected to microbially-induced calcite precipitation (MICP) under various treatment durations, concentrations and flow pressures of cementation reagents. The experimental results showed that the stiffness and peak strength of soil were significantly improved by the MICP treatment. The amount of calcite precipitated showed a linear correlation with recompression index (Cr), reasonable correlations with peak strength (τp) and total settlement (Sc), but a poor correlation with compression index (Cc). Under a high applied stress (exceeds the yield stress of soil), the MICP treatments become ineffective in improving the compressibility characteristics of soil attributed to fracturing of calcite bonds. Cementation reagent with a low flow pressure (i.e. 0.2bar) contributed to more favorable stress-deformation and compressibility responses than those of high flow pressures.