Predicting Moisture-Dependent Resilient Modulus of Cohesive Soils Using Soil Suction Concept
01 Jan 2008-Journal of Transportation Engineering-asce (American Society of Civil Engineers)-Vol. 134, Iss: 1, pp 34-40
TL;DR: In this paper, a new predictive equation for the resilient modulus of cohesive soils using the concept of soil suction is presented, which is validated against experimental data of A-4 and A-6 soils conducted by the writers as well as by other data available in the literature.
Abstract: The resilient modulus of the materials used in various pavement layers has been used extensively as an important material property in structural design of pavement. The state of stress and moisture content of cohesive soils have been observed to exert significant effects on the measured resilient modulus. Since the moisture content in the cohesive subgrade soils underneath the pavement undergoes seasonal changes due to infiltration of precipitations and since characterization of moisture and stress dependent resilient modulus of cohesive soils is a demanding and tedious task, there is a practical need for a predictive equation for the resilient modulus as a function of stress states and moisture content. This paper presents a new predictive equation for the resilient modulus of cohesive soils using the concept of soil suction. The accuracy of the proposed model is validated against experimental data of A-4 and A-6 soils conducted by the writers as well as by other data available in the literature. The proposed model provides advantages over the existing predictive equations by reducing the number of tests and soil specimens needed for determining the regression coefficients in the equation. The proposed predictive equation compares well with the empirical equation in the new mechanistic empirical pavement design guide (MEPDG) in predicting the effect of moisture content variation on the resilient modulus. The proposed model provides an advantage over the MEPDG empirical equation in taking into account the effects of both the stress state and moisture content on the resilient modulus of cohesive soils.
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TL;DR: In this paper, the suitability of the current resilient modulus test protocol (NCHRP 1-28A) for its application to unsaturated soils was assessed, and the results allowed for the enhancement of the Universal Model for resilient Modulus prediction by incorporating suction as a stress state.
Abstract: The suitability of the current resilient modulus test protocol (NCHRP 1-28A) for its application to unsaturated soils was assessed. Modifications to the stress state conditions of the protocol are necessary due to the axis-translation needed during the test when measuring matrix suction. This study presents the modulus of unbound materials resulting from tests performed under unsaturated soil conditions. Two different materials were tested. The base material was tested under drained and undrained boundary conditions, while the subgrade was tested under drained boundary condition. The results allowed for the enhancement of the Universal Model for resilient modulus prediction by incorporating suction as a stress state. This model predicts the resilient response of unbound materials as a function of external stress state and matrix suction levels and therefore, it is independent of moisture variation.
145 citations
Cites background or methods from "Predicting Moisture-Dependent Resil..."
...proposed in 2008 a similar model based on the effective stress approach (Liang et al., 2008)....
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...was chosen for additional comparisons (Liang et al., 2008)....
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...This model is based on the relationship proposed by Moossazadeh and Witczak in 1981, where the Bishop’s effective stress parameter represents the moisture condition of the soil (Moossazadeh et al., 1981)....
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...Therefore, due to its similarity to the Universal Model, the model presented in Equation [6] by Liang et al. was chosen for additional comparisons (Liang et al., 2008)....
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...( ) 21 kmmdR kM ψχσ += [5] where χm is the Bishop’s parameter, and k1, k2 are regression parameters....
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TL;DR: In this article, a new resilient modulus model is proposed to incorporate the moisture dependence of the modulus in addition to the stress dependence in existing models, and prediction models are developed to conveniently and accurately determine the coefficients in the proposed model.
Abstract: This study aims at developing an accurate and efficient methodology to estimate the resilient modulus of unbound aggregates. First, a new resilient modulus model is proposed to incorporate the moisture dependence of the resilient modulus in addition to the stress dependence in existing models. Second, prediction models are developed to conveniently and accurately determine the coefficients in the proposed model. In order to characterize the moisture dependence of unbound aggregates, the degree of saturation and the matric suction parameter are added into the proposed model. The soil-water characteristic curve (SWCC) is used to determine the matric suction value at any given moisture content. The moisture dependence of the model is validated for selected materials with different moisture contents. In order to develop prediction models for the coefficients in the proposed model, laboratory experiments and multiple regression analysis are conducted on 20 different base course materials. The laborator...
97 citations
TL;DR: In this paper, the effectiveness of fly ash (FA) and lime kiln dust (LKD) in soft clays subgrade stabilization is examined, and the results revealed that the addition of Class C FA could increase the dry unit weight of the FA treated soil, enhance the unconfined compressive strength, and improve the resilient modulus.
Abstract: Soft clays are widely distributed in Missouri, United States. Due to their relatively low strength and high compressibility, subgrade construction in soft clays has encountered many difficulties. In recent practice, the use of fly ash (FA) along with lime to tackle soft subgrade problems has shown promising results. The effectiveness of Class C FA and lime kiln dust (LKD) in clay subgrade stabilization is examined in this research. Scanning electron microscopic (SEM) analysis, proctor compaction tests, unconfined compression tests, and resilient modulus tests were carried out on the FA and LKD modified soil mixtures. Test specimens were prepared at optimum water content and tested at various curing periods. The test specimens were reconstituted by static compression. Test results revealed that the addition of Class C FA could increase the dry unit weight of the FA treated soil, enhance the unconfined compressive strength, and improve the resilient modulus. Regression equations were developed to co...
76 citations
Cites background from "Predicting Moisture-Dependent Resil..."
...In previous studies, many researchers have employed the exponential equations to model the improvement of the Mr (Khoury and Zaman 2004; Liang et al. 2008; Yang et al. 2008; Pinilla et al. 2011)....
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...In previous studies, many researchers have employed the exponential equations to model the improvement of the Mr (Khoury and Zaman 2004; Liang et al. 2008; Yang et al. 2008; Pinilla et al. 2011)....
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TL;DR: In this paper, a large database with data from the existing literature and studies at Arizona State University was developed to evaluate the model and the results suggest that the environmental factor is underestimated for fine-grained materials with high plasticity under dry (arid) conditions.
Abstract: The present study deals with the revision of the current model in the Mechanistic-Empirical Pavement Design Guide (MEPDG) used to predict the environmental factor for unfrozen unbound materials (FU), which is used to adjust the resilient response of soils resulting from seasonal changes. A large database with data from the existing literature and studies at Arizona State University was developed to evaluate the model. The results suggest that the environmental factor is underestimated for fine-grained materials with high plasticity under dry (arid) conditions. However, insufficient data were available to enhance the FU models for wetter conditions. Three fundamental factors that may have impacts on the FU values were evaluated in this study: stress state, compaction energy (soil density), and soil type. The stress state was found to have little to no impact on the predictions of FU. But density changes and soil type were found to be important. The potential for soil index properties to be predictive varia...
69 citations
TL;DR: In this paper, the resilient modulus (MR) of pavement subgrade soils is predicted using several models available in the literature for predicting the MR-ψ correla cation.
Abstract: 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 correla...
63 citations
References
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Book•
01 Aug 1993
TL;DR: In this paper, the Mecanique des sols reference record was created on 2004-09-07, modified on 2016-08-08, and it was used for the Sols non satures reference record.
Abstract: Keywords: Mecanique des sols ; Sols non satures Reference Record created on 2004-09-07, modified on 2016-08-08
3,278 citations
TL;DR: In this paper, a nonlinear, least squares computer program is used to determine the best-fit parameters for experimental data presented in the literature, based on the assumption that the shape of the soil-water characteristic curve is dependent upon the pore-size distribution.
Abstract: The soil-water characteristic curve can be used to estimate various parameters used to describe unsaturated soil behaviour. A general equation for the soil-water characteristic curve is proposed. A nonlinear, least-squares computer program is used to determine the best-fit parameters for experimental data presented in the literature. The equation is based on the assumption that the shape of the soil-water characteristic curve is dependent upon the pore-size distribution of the soil (i.e., the desaturation is a function of the pore-size distribution). The equation has the form of an integrated frequency distribution curve. The equation provides a good fit for sand, silt, and clay soils over the entire suction range from 0 to 106 kPa. Key words : soil-water characteristic curve, pore-size distribution, nonlinear curve fitting, soil suction, water content.
2,644 citations
17 Aug 1993
1,931 citations
Journal Article•
677 citations