Resilient Modulus Characterization of Compacted Cohesive Subgrade Soil

Abstract

Soil investigations concerning cyclic loading focus on the evaluation, in particular, of design parameters, such as elastic modulus, Poisson's ratio, or resilient modulus. Structures subjected to repeated loading are vulnerable to high deformations, especially when subgrade soils are composed of cohesive, fully-saturated soils. Such subgrade soils in the eastern part of Europe have a glacial genesis and are a mix of sand, silt, and clay fractions. The characteristic of, e.g., Young modulus variation and resilient modulus from repeated loading tests, is presented. Based on performed resonant column and cyclic triaxial tests, an analytical model is proposed. The model takes into consideration actual values of effective stress p , as well as loading characteristics and the position of the effective stress path. This approach results in better characterization of pavement or industrial foundation systems based on the subgrade soil in undrained conditions. The recoverable strains characterized by the resilient modulus M r value in the first cycle of loading was between 44 MPa and 59 MPa for confining pressure σ' 3 equal to 45 kPa, and between 48 MPa and 78 MPa for σ' 3 equal to 90 kPa. During cyclic loading, cohesive soil, at first, degrades. When pore pressure reaches equilibrium, the resilient modulus value starts to increase. The above-described phenomena indicate that, after the plastic deformation caused by excessive load and excess pore water pressure dissipation, the soil becomes resilient.

Experimental Study on Dynamic Resilient Modulus of Lime‐Treated Expansive Soil

“…Subsequently, the concept of the resilient modulus is quickly accepted by many countries and widely used as one of the main parameters to characterize the mechanical properties of subgrade soil [23]. In recent years, many scholars have studied the influence factors of dynamic resilient modulus of subgrade for different filling materials [24][25][26][27][28]. In brief, the dynamic resilient modulus of clays increases with the increase of confining pressure and compaction and decreases with the increase of dynamic stress and moisture content.…”

Undrained Pore Pressure Development on Cohesive Soil in Triaxial Cyclic Loading

“…Last decade brought attention to cohesive soils tested in drained and undrained conditions. The test results have shown non-cohesive soils' different responses to cyclic loading [21][22][23][24].…”

“…The cohesive soil loaded by long-term cyclic loading, which will not lead to cyclic failure, will suffer the irrecoverable strains and permanent pore pressure [23,[25][26][27].…”

Long-Term Cyclic Loading Impact on the Creep Deformation Mechanism in Cohesive Materials

“…Over the past years, the effect of cyclic loading on the performance of soil structures has been a focus of numerous papers, mainly because of the development of road networks and an increase of human activities in zones where soft soils are subgrade soils. Therefore, the focus for testing has shifted from a dynamic to a quasi-static perspective, where permanent deformation is the main adverse effect [ 1 , 2 , 3 , 4 ]. Previously conducted cyclic loading tests on these types of soils have adopted a two-way manner, and for non-cohesive soils, the liquefaction has been studied extensively [ 5 , 6 , 7 , 8 ].…”

“…The impact of cyclic loading on soil response has the most destructive effect in undrained conditions. Excess pore water pressure decreases the effective stress in the soil skeleton, and therefore failure can occur [ 3 , 9 , 10 , 11 , 12 ].…”