Variation of Resilient Modulus with Soil Suction for Compacted Subgrade Soils

Abstract

The variations of resilient modulus with the postconstruction moisture content and soil suction for cohesive subgrade soils were evaluated. In particular, the effects of relative compaction of the subgrade on the suction and resilient modulus were investigated. To simulate subgrade soils at in-service conditions, soil specimens were compacted at various relative compactions and optimum moisture content and then saturated to equilibrium moisture content to test for resilient modulus and soil suction. The filter paper method was used to measure the total and matric suctions of two cohesive soils. Test findings demonstrated that resilient modulus correlated better with the matric suction than with total suction. Matric suction was found to be a key parameter for predicting the resilient modulus of cohesive subgrade soils. A prediction model incorporating deviator stress and matric suction for subgrade soil resilient modulus was established.

A Review on the Resilient Response of Unsaturated Subgrade Soils

“…Khoury et al [24] demonstrated that the variations in the resilient modulus were not induced by osmotic suction. Based on the analysis of the experimental data, it was found that the resilient modulus correlated better with matric suction than with total suction [4], as illustrated in Figure 3. Furthermore, based on the previous studies, the effects of matric suction should be mainly incorporated in the analysis on the Advances in Civil Engineering behaviour of partially saturated soil in preference to the effects of total and osmotic suctions.…”

“…To reflecting the stress-strain behaviour (i.e., resilient response) of subgrade soils under normal cyclic traffic loading, M r of subgrade soils was introduced by American Association of State Highway and Transportation Officials (AASHTO) [3] as a more rational soil property than the soil support value or modulus of subgrade reaction [4] and therefore is widely employed to estimate transient soil deformation under repeated traffic loads. As a significant stiffness parameter to demonstrate the resilient behaviour, the resilient modulus M r is mathematically defined as the ratio of repeated deviator stress q to axial recoverable strain (i.e., resilient strain) ε r [5] as follows:…”

“…In the condition of optimum moisture content (OMC), the easiest compaction can be performed, and the maximum density will be acquired [14]. us, to achieve the maximum dry density (MDD) of subgrade soils, construction specifications universally require that the soils be compacted at (or near) OMC in practice, and therefore all placed and many in-situ subgrade soils should be regarded as materials in an unsaturated state above the water table [4,15] or in a near-saturated condition. Due to the environmental conditions (e.g., wetting and drying, freezing and thawing, and precipitation), unsaturated soils will be subjected to seasonal variations in moisture content [15][16][17][18].…”

Effects of Density and Moisture Variation on Dynamic Deformation Properties of Compacted Lateritic Soil

“…However, during the service life of a subgrade, the moisture content at the time of compaction is not constant and firstly changes to an equilibrium water content (EPC) and then fluctuates along the EPC due to the seasonal environmental factors such as groundwater table variation, rainwater infiltration, and evaporation [1][2][3][4][5]. Several recent studies have shown that variations in moisture content significantly degrade the engineering properties of compacted subgrade [6][7][8][9] and contribute to the deterioration and premature failure of pavements. It is evident that proper consideration to the effect of moisture variation should be given in realistic pavement design and analysis.…”

Estudo de parâmetros de compactação de solo para uso em pavimentos rodoviários

“…De acordo com Badillo & Rodrigues (1976) dentre os fatores que influenciam a compactação obtida os mais importantes são a umidade e energia de compactação e entre os que influenciam a sucção nos solos pode-se citar a granulometria, a composição químico-mineralógica, trajetória de umedecimento e secagem na curva característica (Neto e Carvalho, 1995;Rodrigues, 1997). Alguns estudos (VA-NAPALLI et al, 1999;SIMMS e YANFUL, 2000;LU e LIKOS, 2004;YANG et al, 2005 Nesse sentido, a literatura mostra que a manifestação física da sucção se dá na forma de uma pressão negativa na água que cria uma forte ligação entre as partículas de solo aumentando sua resistência ao cisalhamento e a rigidez da estrutura (Mullins, 1990;McKyes et al 1994;Marinho, 1997;Nogueira, 2005;Delgado, 2007). No entanto, faz-se necessário entender que quando o mecanismo é o capilar, essa energia, ao aumentar a tensão nos contatos, amplia a resistência e rigidez dos materiais.…”