scholarly journals A Review on the Resilient Response of Unsaturated Subgrade Soils

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xuanxuan Chu
Keyword(s):  
Moisture Content ◽  
Unsaturated Soils ◽  
Resilient Modulus ◽  
Model Development ◽  
Matric Suction ◽  
Affecting Factors ◽  
Wetting And Drying ◽  
Subgrade Soils ◽  
Subgrade Modulus ◽  
Resilient Response

Considering the great contribution of subgrade modulus to the overall performance of roads or railways, it is crucial to provide the best prediction of resilient modulus for their foundations. Incorporating the seasonal variation of moisture content, the resilient modulus variation of unsaturated soils will be accurately predicted. This paper aims to introduce and discuss the knowledge about resilient response of unsaturated soils and emphasize the effects of humidity. A literature review on resilient response of unsaturated soils is presented based on the previous studies. The affecting factors (i.e., wetting and drying, moisture content, and matric suction) were discussed. The prediction model development of the resilient response of unsaturated soils was presented. The limitations and advantages of the model were analyzed and compared. It reveals that the current models were limited regarding stress conditions, moisture content, matric suction, and soil types, and further studies are still needed to achieve a better understanding of resilient response of unsaturated soils.

Variation of Resilient Modulus with Soil Suction for Compacted Subgrade Soils

2005 ◽  
Vol 1913 (1) ◽  
pp. 99-106 ◽  
Author(s):  
Shu-Rong Yang ◽  
Wei-Hsing Huang ◽  
Yu-Tsung Tai
Keyword(s):  
Moisture Content ◽  
Resilient Modulus ◽  
Matric Suction ◽  
Soil Suction ◽  
Subgrade Soils ◽  
Subgrade Soil ◽  
Relative Compaction ◽  
Service Conditions ◽  
Paper Method ◽  
Key Parameter

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.

Model for predicting resilient modulus of unsaturated subgrade soil using soil-water characteristic curve

2015 ◽  
Vol 52 (10) ◽  
pp. 1605-1619 ◽  
Author(s):  
Zhong Han ◽  
Sai K. Vanapalli
Keyword(s):  
Moisture Content ◽  
Soil Water ◽  
Resilient Modulus ◽  
Characteristic Curve ◽  
Optimum Moisture Content ◽  
Model Parameters ◽  
Soil Water Characteristic Curve ◽  
Subgrade Soils ◽  
Fine Grained ◽  
Proposed Model

Soil suction (ψ) is one of the key factors that influence the resilient modulus (MR) of pavement subgrade soils. There are several models available in the literature for predicting the MR–ψ correlations. However, the various model parameters required in the existing models are generally determined by performing regression analysis on extensive experimental data of the MR–ψ relationships, which are cumbersome, expensive, and time-consuming to obtain. In this paper, a model is proposed to predict the variation of the MR with respect to the ψ for compacted fine-grained subgrade soils. The information of (i) the MR values at optimum moisture content condition (MROPT) and saturation condition (MRSAT), which are typically determined for use in pavement design practice; (ii) the ψ values at optimum moisture content condition (ψOPT); and (iii) the soil-water characteristic curve (SWCC) is required for using this model. The proposed model is validated by providing comparisons between the measured and predicted MR–ψ relationships for 11 different compacted fine-grained subgrade soils that were tested following various protocols (a total of 16 sets of data, including 210 testing results). The proposed model was found to be suitable for predicting the variation of the MR with respect to the ψ for all the subgrade soils using a single-valued model parameter ξ, which was found to be equal to 2.0. The proposed model is promising for use in practice, as it only requires conventional soil properties and alleviates the need for experimental determination of the MR–ψ relationships.

scholarly journals Estimation of Resilient Modulus for Coarse-Grained Subgrade Soils from Quick Shear Tests for Mechanistic-Empirical Pavement Designs

Designs ◽  
2019 ◽  
Vol 3 (4) ◽  
pp. 48
Author(s):  
Md Mostaqur Rahman ◽  
Kazi Moinul Islam ◽  
Sarah Gassman
Keyword(s):  
South Carolina ◽  
Moisture Content ◽  
Resilient Modulus ◽  
Tangent Modulus ◽  
Coarse Grained ◽  
Unit Weight ◽  
Index Properties ◽  
Subgrade Soils ◽  
Dry Unit Weight ◽  
Technical Ability

The resilient modulus represents the subgrade soil stiffness, and it is considered one of the key material inputs in the Mechanistic Empirical Pavement Design Guide (MEPDG). The resilient modulus is typically estimated in the laboratory using a repeated load cyclic triaxial test, which is complex and time consuming to perform. Technical ability is also required to prepare the test specimens, particularly for coarse-grained soils. Therefore, there is a need to estimate the resilient modulus of coarse-grained soils from other simpler tests. In this study, correlations of resilient modulus with soil index properties and quick shear (QS) test results (quick shear strength, stress at 1% strain and tangent modulus) were developed for remolded coarse-grained soils, collected from different geographic regions in South Carolina. The developed models showed good correlations of resilient modulus to tangent modulus and soil index properties. The average tangent, modulus obtained from 30% and 50% of maximum stress of the QS tests, moisture content, optimum moisture content, dry unit weight, and maximum dry unit weight showed a statistically significant effect on estimating the resilient modulus for coarse-grained subgrade soils. The validation study confirms that the developed models can be used for predicting the resilient modulus for South Carolina coarse-grained soils.

scholarly journals Modelling resilient modulus seasonal variation of silty sand subgrade soils with matric suction control

2014 ◽  
Vol 51 (12) ◽  
pp. 1413-1422 ◽  
Author(s):  
Farhad Salour ◽  
Sigurdur Erlingsson ◽  
Claudia E. Zapata
Keyword(s):  
Stress State ◽  
Moisture Content ◽  
Prediction Model ◽  
Pore Pressure ◽  
Resilient Modulus ◽  
Matric Suction ◽  
Pressure Effects ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Suction Control

The resilient modulus of unbound materials is an important parameter in the mechanistic design of pavements. Although unbound layers are frequently in a partially saturated state, a total stress approach is conventionally used in modeling the material behaviour, and therefore pore pressure effects are not considered. In fine-grained unbound materials, the saturation state can affect their mechanical behaviour due to pore pressure effects. In this study a modified test procedure and a predictive resilient modulus model that takes into account the subgrade soil matric suction as a stress state variable is presented. Two different silty sand subgrade materials were tested in unsaturated conditions using a series of repeated load triaxial tests under controlled pore suction conditions to study its influence on the resilient modulus. The test data were further used to obtain the resilient modulus model regression parameters that account for moisture content variations through the matric suction parameter. Generally, the prediction model could effectively capture the resilient modulus behaviour of the subgrades with respect to changes in the normal stress state and the matric suction. Given the completeness of this method, this prediction model is recommended as an improved approach in capturing the moisture content effects on the material stiffness properties.

scholarly journals The, K.M. A Study on the Relationship Between Matric Suction and the Void Ratio and Moisture Content of a Compacted Unsaturated Soil

2018 ◽  
Author(s):  
Minh The Kieu ◽  
András Mahler
Keyword(s):  
Moisture Content ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Void Ratio ◽  
Clayey Soil ◽  
Matric Suction ◽  
Moisture Ratio ◽  
Distinct Advantage ◽  
State Variables ◽  
Test Procedures

The volumetric behaviour of compacted unsaturated soils is particularly complex due to the co-existence of three different phases: solid, liquid and air. Matric suction has been perceived as a significant influence on the volumetric behaviour of unsaturated soils and has been used as one of the constitutive variables for most the constitutive models of unsaturated soils in the literature. However, suction-controlled works are complex in practice since they generally require special test procedures and advanced equipment, and usually are very time-consuming. Thus, some researchers have tried to seek alternative frameworks that use the traditional choice of state variables to simulate the behaviour of unsaturated soils. Recently, Kodikara [1] proposed the MPK framework to interpret the behaviour of compacted unsaturated soil in the void ratio (e) – net stress (p) – moisture ratio (ew ) space. The distinct advantage of the model is that it is based on traditional constant moisture content compaction testing which is more common and simple than constant suction loading. The MPK framework has been shown to be capable of presenting the volumetric behaviour of compacted unsaturated soils. However, this framework is expected to use not only for compacted soil but for the behaviour of unsaturated soil in general. The incorporation of soil suction within the MPK framework can be helpful for creating a correlation with previous models which used matric suction as a constitutive variable. This paper presents the development of LWSBS for one clayey soil in Hungary within the MPK framework and then suction is incorporated, which is related to void ratio and moisture ratio through SWCC.

Study on Prediction Model of Dynamic Resilient Modulus of Cohesive Subgrade Soils Considering Moisture Variation

2014 ◽  
Vol 488-489 ◽  
pp. 411-416 ◽  
Author(s):  
Zhi Yong Li ◽  
Jing Rong Zou ◽  
Cheng Dong
Keyword(s):  
Moisture Content ◽  
Prediction Model ◽  
Filter Paper ◽  
Resilient Modulus ◽  
Subgrade Soils ◽  
Deviator Stress ◽  
Filter Paper Method ◽  
Bulk Stress ◽  
Effect Of Moisture ◽  
Paper Method

The matric suctions were measured by the filter paper method, and the parameters of soil-water characteristic curve were obtained. In order to investigate the effect of moisture content on cohesive subgrade soils dynamic resilient modulus, a series of dynamic-triaxial test were carried out. Based on the matric suctions measured by the filter paper method, the relationship between dynamic resilient modulus and matric suctions were analyzed. The study demonstrated that the dynamic resilient modulus values decrease with the increase of circular deviator stress and moisture content, in reverse of matric suctions. Considering that the dynamic resilient modulus is a function of deviator stress and bulk stress, based on the present three parameters compound constitutive model which reflects the effect of bulk stress and deviator stress, the effect of matric suctions which could indirectly reflect the effect of moisture content was introduced. And then the prediction model incorporating the effect of stress and moisture for cohesive subgrade soils was established. The model was utilized for experimental data regression analysis, a high coefficient of determination shows that the model is accurate and credible. The prediction models not only can evaluate the long-term performance of subgrade soil in Southern China's rainy areas, but also can provide parameters for the pavement design based on dynamic method.

Resilient modulus modeling of unsaturated subgrade soils with matric suction control

2014 ◽  
pp. 1145-1154
Author(s):  
Farhad Salour ◽  
Sigurdur Erlingsson ◽  
Claudia Zapata
Keyword(s):  
Resilient Modulus ◽  
Matric Suction ◽  
Subgrade Soils ◽  
Suction Control

scholarly journals Integrated approaches for predicting soil-water characteristic curve and resilient modulus of compacted fine-grained subgrade soils

2017 ◽  
Vol 54 (5) ◽  
pp. 646-663 ◽  
Author(s):  
Zhong Han ◽  
Sai K. Vanapalli ◽  
Wei-lie Zou
Keyword(s):  
Moisture Content ◽  
Soil Water ◽  
Resilient Modulus ◽  
Characteristic Curve ◽  
Experimental Studies ◽  
Pavement Design ◽  
Soil Water Characteristic Curve ◽  
Subgrade Soils ◽  
Fine Grained ◽  
Integrated Approaches

This paper combines a series of approaches for predicting the soil-water characteristic curve (SWCC) and the variation of the resilient modulus (MR) of compacted fine-grained subgrade soils with moisture content, which is the key information required in mechanistic pavement design methods. The presented approaches for the SWCC and MR are integrated, as (i) they are developed following the same philosophy, (ii) they require only the measurements of the suction and moisture content or MR at saturated and optimum moisture content conditions for prediction, and (iii) the predicted SWCC is used for predicting the MR – moisture content relationship. Experimental studies have been performed on five fine-grained subgrade soils that were collected from different regions in Ontario, Canada, to determine their MR at various external stress levels and post-compaction moisture contents, as well as their SWCCs after the MR tests. Experimental measurements are predicted using the integrated approaches and the empirical approaches currently used in the mechanistic–empirical pavement design guide (MEPDG). It is demonstrated that the integrated approaches are easy to use and show improved reliability in predicting both the SWCC and MR for the investigated subgrade soils in spite of using limited experimental data.

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